IS-QZSS_14_E

March 28, 2018 | Author: Hoàng Phương | Category: Global Positioning System, Telecommunications Engineering, Spaceflight, Aerospace Engineering, Aerospace
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IS-QZSS Ver. 1.4 Quasi-Zenith Satellite System Navigation Service Interface Specification for QZSS (IS-QZSS) V1.4 Japan Aerospace Exploration Agency February 28, 2012 IS-QZSS Ver. 1.4 Preface JAXA is pleased to announce the publication of IS-QZSS Version 1.4 on the QZSS website (http://qzss.jaxa.jp/is-qzss/index_e.html) on 28 February 2012. This is a revision notice on the IS-QZSS Version 1.3 previously released on June 2011. Main items to be updated are following; Adding updated information for operating QZS-1 after the launching JAXA will gather comments on the document from user communities as it was done for previous publication of IS-QZSS. JAXA always welcomes comments and questions from users as part of our commitment to continually improve both this IS-QZSS document and the QZSS. We also welcome communication with receiver manufacturers concerning the design and manufacturing of receivers. Disclaimer (1) IS-QZSS and L-band Positioning Signal transmitted from QZS-1 (hereinafter referred to as “Signals” collectively) is provided without any warranty including but not limited to accuracy, usefulness, Positioning Signal continuity and fitness for a particular purpose of use of the Signals. (2) No liability is assumed for any direct or indirect damages resulting from the use of the Signals, or from any product or service developed based on the Signals. IS-QZSS Ver. 1.4 REVISION RECORD LTR DESCRIPTION DATE APPROVED 1.0 Initial release 17 June 2008 1.1 Adding new message type “No. 20” to LEX signal for the experiment to be conducted by Geographical Survey Institute. Adding notes on items to be modified according to the progress of GPS L1C design. 31July 2009 1.2 Adding notes on QZSS L1C message description to be modified according to the progress of GPS L1C message design. Adding the information for L1-SAIF+ message Adding the information for QZSS Website and Operational information and Data Adding notes on items to be modified according to the progress of developing IMES(Indoor Messaging System) Typo or editorial correction 25 Feb. 2011 1.3 Adding notes on QZSS L1C message description to be modified according to the progress of GPS L1C message design. Adding the information for SPAC-LEX signal Adding updating information for QZS-1 operating after the launching Typo or editorial correction 22 June 2011 1.4 Adding updating information for QZS-1 operating after the launching Typo or editorial correction 28 Feb. 2012 IS-QZSS Ver. 1.4 i Table of Contents 1 SCOPE ..................................................................................................................................................... 1 2 APPLICABLE DOCUMENTS .............................................................................................................. 3 3 OVERVIEW OF QZSS .......................................................................................................................... 4 3.1 OVERVIEW OF QZSS ................................................................................................................. 5 3.1.1 System Overview .............................................................................................................. 5 3.1.2 Operation ........................................................................................................................ 12 3.1.3 Signals transmitted by QZS = QZS Signals .................................................................... 18 3.1.4 Time System and Coordinate System ............................................................................. 24 3.2 INTERFACE WITH OTHER SYSTEMS .......................................................................................... 25 3.2.1 QZSS Time System Relative to Other GNSS .................................................................. 25 3.2.2 QZSS Coordinate System Relative to Other GNSS ........................................................ 25 4 QZSS COVERAGE, AVAILABILITY AND PERFORMANCE .................................................... 27 4.1 QZSS SERVICE AREA .............................................................................................................. 27 4.1.1 Single QZS Coverage Area .............................................................................................. 27 4.1.2 QZSS Coverage Area ....................................................................................................... 28 4.1.3 Elevation Angle Variation for QZSS Constellation ......................................................... 29 4.1.4 QZSS constellation availability....................................................................................... 30 4.1.5 Target Regions for Ionospheric Parameters Transmitted by QZS .................................. 30 4.1.6 Availability Improvement when QZSS and Galileo are Combined with GPS ................ 31 4.2 SERVICE AVAILABILITY ............................................................................................................ 37 4.2.1 The fixed initial right ascension of ascending node depending on the launch time ....... 37 4.3 SYSTEM PERFORMANCE .......................................................................................................... 39 4.3.1 Availability ...................................................................................................................... 39 4.3.2 Alert flag, URA and Health Data .................................................................................... 39 4.3.3 Accuracy .......................................................................................................................... 40 5 QZSS SIGNAL PROPERTIES .......................................................................................................... 42 5.1 QZS POWER LEVELS, BANDWIDTHS AND CENTER FREQUENCIES ............................................. 42 5.1.1 Overview of signal properties ......................................................................................... 43 5.1.2 Navigational messages ................................................................................................... 50 5.2 L1C/A SIGNAL ......................................................................................................................... 54 5.2.1 RF characteristics ........................................................................................................... 54 5.2.2 Messages ......................................................................................................................... 54 5.3 L1C SIGNAL............................................................................................................................ 65 5.3.1 RF Characteristics .......................................................................................................... 65 5.3.2 Messages ......................................................................................................................... 66 5.4 L1-SAIF SIGNAL ..................................................................................................................... 83 IS-QZSS Ver. 1.4 ii 5.4.1 RF characteristics ........................................................................................................... 83 5.4.2 Error Correction Code ..................................................................................................... 83 5.4.3 Message ........................................................................................................................... 83 5.5 L2C SIGNAL .......................................................................................................................... 107 5.5.1 RF characteristics ......................................................................................................... 107 5.5.2 Message ......................................................................................................................... 107 5.6 L5 SIGNAL............................................................................................................................. 121 5.6.1 RF characteristics ......................................................................................................... 121 5.6.2 Message ......................................................................................................................... 121 5.7 LEX SIGNAL ......................................................................................................................... 136 5.7.1 RF Signal Characteristics ............................................................................................. 136 5.7.2 LEX Messages ............................................................................................................... 139 6 USER ALGORITHMS ....................................................................................................................... 164 6.1 CONSTANTS .......................................................................................................................... 164 6.1.1 Speed of Light ............................................................................................................... 164 6.1.2 Angular Velocity of the Earth's Rotation ...................................................................... 164 6.1.3 Earth's Gravitational Constant .................................................................................... 164 6.1.4 Circular Constant ......................................................................................................... 164 6.1.5 Semi-Circle .................................................................................................................... 164 6.2 USER ALGORITHMS RELATING TO TIME SYSTEMS AND COORDINATE SYSTEMS .......................... 164 6.2.1 User algorithms relating to time systems..................................................................... 164 6.2.2 User Algorithms relating to Coordinate Systems ......................................................... 165 6.3 COMMON GNSS ALGORITHMS ............................................................................................... 166 6.3.1 Time Relationships ....................................................................................................... 166 6.3.2 User Algorithm for SV Clock Offset .............................................................................. 167 6.3.3 Ionospheric Delay Correction for Dual Frequency Users ............................................. 168 6.3.4 Correction of Inter-Signal Group Delay Error by Users of Only One Signal ................ 171 6.3.5 Calculation of Satellite Orbit using Ephemeris Data ................................................... 172 6.3.6 Calculation of Satellite Orbit and SV Clock Offset using Almanac Data ..................... 172 6.3.7 Calculation of Coordinated Universal Time (UTC) using the global standard time parameter .............................................................................................................................. 174 6.3.8 Correction of Ionospheric Delay Using Ionospheric Parameters .................................. 174 6.3.9 Correction Using NMCT (L1C/A Signal) and DC Data (L1C, L2C and L5 Signals) ..... 174 6.3.10 User Algorithms Relating to Interoperability with Other Satellite Navigation Systems 175 6.4 L1 SAIF ALGORITHM ............................................................................................................ 176 6.4.1 Validity period (Time-out period) .................................................................................. 176 6.4.2 Error Correction Algorithm........................................................................................... 176 6.4.3 Algorithm for Integrity information .............................................................................. 183 IS-QZSS Ver. 1.4 iii 6.4.4 Calculation of QZSS satellite Position .......................................................................... 185 6.5 LEX ALGORITHM .................................................................................................................. 186 6.5.1 Reed Solomon Coding/Decoding Algorithm for LEX Navigation Message.................... 186 6.6 OTHER INFORMATION ........................................................................................................... 189 6.6.1 Instrumental Bias in Receivers .................................................................................... 189 7 PROVISION OF QZSS OPERATIONAL INFORMATION AND DATA VIA THE INTERNET 190 7.1 QZSS WEBSITE FOR OPERATIONAL INFORMATION AND DATA ................................................. 190 7.2 RELEASE OF QZSS INFORMATION AND DATA ......................................................................... 190 7.2.1 NAQU (NOTICE ADVISORY TO QZSS USERS） ....................................................... 190 7.2.2 Experimental Schedule ................................................................................................. 191 7.2.3 Evaluation result for System Performances ................................................................. 191 7.2.4 User Operation Support Tool ........................................................................................ 191 7.2.5 Provision of Precise Orbit & Clock for QZSS and GPS ................................................. 192 7.2.6 Detailed Information for Precise Orbit & Clock Estimation for research purposes ..... 192 8 DIFFERENCES WITH GPS ............................................................................................................. 193 8.1 DIFFERENCES IN NAVIGATION MESSAGES .............................................................................. 193 8.1.1 Differences with GPS in terms of L1C/A signal ............................................................ 193 8.1.2 Differences with GPS in terms of CNAV message on L2C and L5 signals ................... 194 8.1.3 Differences with GPS in terms of CNAV2 message on L1C signals ............................. 195 8.2 DIFFERENCE OF RF CHARACTERISTICS ................................................................................. 197 8.2.1 Difference of Modulated Diffusion Method of Signal .................................................... 197 8.2.2 Difference of Signal Phase Relation of LIC Signal ....................................................... 197 IS-QZSS Ver. 1.4 iv List of Figures Figure 3.1.1-1 System overview........................................................................................... 5 Figure 3.1.1-2 QZSS Orbit and Ground Track Diagram for the Three-Satellite Constellation....... 6 Figure 3.1.1-3 Constellation Orbit Track Diagram (EPOCH=2009/Dec/26/12:00UTC) for the Three-Satellite Constellation ........................................................................................ 6 Figure 3.1.1-4 QZS Orbit Ground Tracks ............................................................................. 8 Figure 3.1.1-5 QZS ........................................................................................................... 9 Figure 3.1.1-6 QZS Block Diagram ...................................................................................... 9 Figure 3.1.1-7 Mapping of Ground Stations ..........................................................................10 Figure 3.1.1-8 MCS ..........................................................................................................11 Figure 3.1.1-9 TTC Antenna .............................................................................................11 Figure 3.1.2-1 System data flow .........................................................................................12 Figure 3.1.2-2 An example of the update timing of the navigation message ...............................13 Figure 3.1.2-3 An example of uplink timing of the navigation message .....................................14 Figure 3.1.2-4 Relationship between "Alert" flag and URA/NSC switching ...............................16 Figure 3.1.2-5 Range of Orbital Maintenance .......................................................................17 Figure 3.1.3-1 Power Spectral Density of QZS Signals ...........................................................18 Figure 3.1.3-2 Relative velocity of signals (Change rate of distance) between each city and QZS-1 (See Table 3.1.1-1 for calculation condition. Observation EPOCH = 2009/Dec/26/12:00UTC. Horizontal axis means elapsed time from EPOCH.) .........................................................20 Figure 3.1.3-3 Elevation and Azimuthal angles for each city (See Table 3.1.1-1 for calculation condition. Observation EPOCH = 2009/Dec/26/12:00 UTC) ..........................................22 Figure 3.1.3-4 Changes of received signal power level for each city (See Table 3.1.1-1 for calculation condition. Observation EPOCH = 2009/Dec/26/ 12:00 UTC. Horizontal axis means elapsed time from EPOCH.) ...............................................................................23 Figure 3.2.1-1 Diagram of Time System Relationships between QZSS, GPS and Galileo ..............25 Figure 3.2.2-1 Convergence of Geodetic Coordinate Systems .................................................26 Figure 4.1.1-1 Percentage of Time during which a Single QZS can be seen at an Elevation Angle of 10° or more .............................................................................................................27 Figure 4.1.1-2 Percentage of Time during which a Single QZS can be seen at an Elevation Angle of 60° or more .............................................................................................................27 Figure 4.1.2-1 Percentage of Time during which at least One QZS in the 3-satellite QZSS constellation can be seen at an Elevation Angle of 10° or more ......................................28 Figure 4.1.2-2 Percentage of Time during which at least One QZS in the 3-satellite QZSS constellation can be seen at an Elevation Angle of 60° or more ......................................28 Figure 4.1.3-1 Variation of QZSS Constellation (for 3 satellites) Elevation Angles for eight cities (See Table 3.1.1-1 for calculation condition of QZS-1. For QZS-2 and 3, we assumed the right ascension of ascending node is +/- 120 deg from that value of QZS-1. Observation EPOCH = 2009/Dec/26/12:00UTC Horizontal axis means elapsed time from EPOCH.) .....................29 Figure 4.1.4-1 Average Number of QZS Satellites that can be seen at an Elevation Angle of 10° or IS-QZSS Ver. 1.4 v more with the 3-satellite QZSS Constellation .................................................................30 Figure 4.1.5-1 Target Regions for Ionospheric Parameters Transmitted by QZS ........................30 Figure 4.1.6-1(1/2) Percentage of Time when PDOP < 6 for an Elevation Angle Mask of 20° ....32 Figure 4.1.6-2 (1/3) Average Number of Visible Satellites for an Elevation Angle Mask of 10° ..34 Figure 4.2.1-1 Initial Single-satellite QZSS Visibility Time for eight Reference Locations. (See Table 3.1.1-1 for calculation condition. Dark shaded areas represent elevation angles of 60[deg] or more; light blue areas represent elevation angles of 10[deg] to 60[deg] and white is less than 10[deg]; vertical scale is hours on UTC and JST.) ..........................................................38 Figure 4.3.2-1 “Alert” flag, URA, Health Data and Integrity Data Maximum Notification Time ...40 Figure 5.1.1-1 Phase Relations of LI Signal for QZS-1 and GPS ..............................................44 Figure 5.1.1-2 Phase Noise of all QZS signals.......................................................................45 Figure 5.1.1-3 Definition of code jitter σ jitter ........................................................................46 Figure 5.1.1-4 Definition of delay time, Δ, for PRN code rising/falling edge .............................47 Figure 5.1.2-1 QZS URA and Health Data on L1C/A signal ...................................................50 Figure 5.3.1-1 L1C Signal Structure ...................................................................................65 Figure 5.3.2-1 Relationship between TOI, ITOW & time of week ............................................69 Figure 5.4.2-1 FEC Generation Method ..............................................................................83 Figure 5.4.3-1 Message Block Format .................................................................................84 Figure 5.6.1-1 L5 Signal Structure .................................................................................... 121 Figure 5.7.1-1 LEX Signal Structure ................................................................................. 136 Figure 5.7.1-2 Block diagram of LEX code generation ......................................................... 137 Figure 5.7.1-3 Timing Relationship between the LEX Short Code and Long Code ................... 138 Figure 5.7.2-1 LEX Message Structure ............................................................................. 139 Figure 5.7.2-2 Reed-Solomon Encoding ............................................................................. 141 Figure 5.7.2-3 Data Part, Message Type 10 – Signal Health, Ephemeris & SV Clock ............... 142 Figure 5.7.2-4 Data Part, Message Type 11 – Signal Health, Ephemeris & SV Clock and Ionospheric Correction .............................................................................................................. 143 Figure 5.7.2-5 Signal Health Packet Structure .................................................................... 145 Figure 5.7.2-6 Ephemeris & SV Clock Packet Content ........................................................ 148 Figure 5.7.2-7 Ionospheric Correction Packet Content ........................................................ 155 Figure 6.4.2-1 Definition of interpolation with four surrounding IGPs ..................................... 180 Figure 6.4.2-2 Definition of interpolation with three surrounding IGPs ................................... 181 IS-QZSS Ver. 1.4 vi List of Tables Table 3.1.1-1 Calculation condition for QZS-1 nominal orbit ................................................... 8 Table 3.1.1-2 Location of Ground Station ............................................................................10 Table 3.1.3-1 General Specifications for QZS Signals.............................................................19 Table 3.1.3-2 Doppler coefficients for signals .......................................................................21 Table 4.3.3-1 Positioning Accuracy by means of Availability Enhancement Signals ....................41 Table 4.3.3-2 Positioning Accuracy by means of Performance Enhancement Signals ...................41 Table 5.1-1 QZS signal specifications ..................................................................................42 Table 5.1.1-1 Configuration of QZS signals ..........................................................................43 Table 5.1.1-2 Differences in Pseudo Random Noise (PRN) code phases among QZS signals .........48 Table 5.1.2-1 Details of Health (5-bit health) code for all QZSS signals ...................................51 Table 5.2.2-1 Content identification using Data ID and Space Vehicle ID .................................59 Table 5.2.2-2 Sequence of Satellite Health in the frame when Data-ID=11 ...............................61 Table 5.2.2-3 Sequence of NMCT in the frame when Data-ID=11 ...........................................64 Table 5.3.2-1 Definition of Ephemeris parameters and SV clock parameters for Navigational Message D L1C .........................................................................................................................68 Table 5.3.2-2 Definition of page number and transmit periods for Navigational Message D L１C ......72 Table 5.3.2-3 Definition of UTC parameters and Ionospheric parameters for Navigational Message D L１C .........................................................................................................................73 Table 5.3.2-4 Definition of GPS GNSS Time Offset (GGTO) and EOP parameters for Navigational Message D L１C ............................................................................................................75 Table 5.3.2-5 Definition of Reduced Almanac parameters for Navigational Message D L１C ............76 Table 5.3.2-6 Definition of Midi Almanac parameters for Navigational Message D L１C ..................79 Table 5.3.2-7 Definition of DC data for Navigational Message D L１C .........................................81 Table 5.4.3-1 SAIF Message Types .....................................................................................85 Table 5.4.3-2 Message Type 1: PRN Mask Data ...................................................................87 Table 5.4.3-3 PRN Slot Assignments to GNSS Satellites ........................................................88 Table 5.4.3-4 Message Types 2 - 5: Fast Correction ............................................................89 Table 5.4.3-5 UDRE value .................................................................................................89 Table 5.4.3-6 Message Type 6: Integrity Data ......................................................................90 Table 5.4.3-7 Message Type 7: Fast Correction Degradation Factor .......................................90 Table 5.4.3-8 Message Type 10: Degradation Parameter........................................................91 Table 5.4.3-9 Message Type 18 Format: IGP Mask ...............................................................92 Table 5.4.3-10 Specification of IGP locations .......................................................................93 Table 5.4.3-11 Message Type 24 (Fast & Long-term Corrections) ..........................................98 Table 5.4.3-12 Message Type 25: Long-Term Correction ......................................................99 Table 5.4.3-13 Partial message format of Message Type 25 ....................................................99 Table 5.4.3-14 Message Type 26: Ionospheric Delay Correction ........................................... 100 Table 5.4.3-15 GIVEI Value ............................................................................................. 100 Table 5.4.3-16 Message Type 28: Clock - Orbit Covariance ................................................ 101 IS-QZSS Ver. 1.4 vii Table 5.4.3-17 Message Type 63 (Null Message) ................................................................ 101 Table 5.4.3-18 Message Type 52：TGP Mask...................................................................... 102 Table 5.4.3-19 Specification of TGP locations .................................................................... 103 Table 5.4.3-20 Message type 53：Zenith Tropospheric Delay Correction ................................ 105 Table 5.4.3-21 Message Type 56: Inter Signal Bias Correction Data ...................................... 105 Table 5.4.3-22 QZS Ephemeris Data ................................................................................. 106 Table 5.5.2-1 Definitions of message types for Navigational Message D L2C .............................. 108 Table 5.5.2-2 Maximum Transmit periods for Navigational Message D L2C ................................ 108 Table 5.5.2-3 Definition of Ephemeris parameters for Navigational Message D L2C .................... 110 Table 5.5.2-4 Definition of SV clock parameters for Navigational Message D L2C ...................... 112 Table 5.5.2-5 Definition of ionospheric parameters for Navigational Message D L2C ................... 113 Table 5.5.2-6 Group Delay Correction Parameters (T GD , ISC) for Navigational Message D L2C .... 114 Table 5.5.2-7 Definition of Midi Almanac parameters for Navigational Message D L2C ................ 115 Table 5.5.2-8 Definition of Reduced Almanac parameters for Navigational Message D L2C .......... 115 Table 5.5.2-9 Definition of parameters for DC data for Navigational Message D L2C .................. 119 Table 5.5.2-10 Definition of GPS GNSS Time Offset (GGTO) parameters for Navigational Message D L2C ....................................................................................................................... 120 Table 5.6.2-1 Definitions of message types for Navigational Message D L5 ............................... 122 Table 5.6.2-2 Maximum Transmit periods for Navigational Message D L5 ................................. 123 Table 5.6.2-3 Definition of Ephemeris parameters for Navigational Message D L5 ..................... 125 Table 5.6.2-4 Definition of SV clock parameters for Navigational Message D L5 ....................... 127 Table 5.6.2-5 Definition of ionospheric parameters for Navigational Message D L5 .................... 128 Table 5.6.2-6 Group Delay Correction Parameters (T GD , ISC) for Navigational Message D L5 ..... 129 Table 5.6.2-7 Definition of Midi Almanac parameters for Navigational Message D L5 ................. 130 Table 5.6.2-8 Definition of Reduced Almanac parameters for Navigational Message D L5 ............ 130 Table 5.6.2-9 Definition of parameters for DC data for Navigational Message D L5 .................... 134 Table 5.6.2-10 Definition of GPS GNSS Time Offset (GGTO) parameters for Navigational Message D L5 ......................................................................................................................... 135 Table 5.7.1-1 LEX code phase assignment ......................................................................... 138 Table 5.7.2-1 Definition of message type ........................................................................... 140 Table 5.7.2-2 Definition of ephemeris parameters for Navigational Message D LEX navigation message ............................................................................................................................. 149 Table 5.7.2-3 Definition of SV clock and group delay parameters for Navigational Message D LEX navigation messages ................................................................................................. 153 Table 5.7.2-4 Definition of ionospheric correction parameters for LEX navigation messages ..... 154 Table 5.7.2-5 Message type 10,11：broadcast interval, update interval and valid time .............. 157 Table 5.7.2-6 The Record Structure of Message Type 20 ..................................................... 158 Table 5.7.2-7 Parameter-type ID...................................................................................... 158 Table 5.7.2-8 Observation Information of the Reference Stations .......................................... 159 Table 5.7.2-9 GPS Smoothing Interval ............................................................................... 160 IS-QZSS Ver. 1.4 viii Table 5.7.2-10 GPS L1 Lock time Indicator ....................................................................... 160 Table 5.7.2-11 Satellite Orbit and Clock Correction Information ＋ Ionosphere Grid Interval Information .............................................................................................................. 161 Table 5.7.2-12 Tropospheric Delay Correction Information .................................................. 162 Table 5.7.2-13 Ionospheric Delay Correction Information .................................................... 162 Table 6.4.1-1 Validity Periods for L1-SAIF Message Parameters .......................................... 176 Table 6.4.3-1 Relations of integrity and Constants “K” ....................................................... 183 Table 7.2-1 Provision of QZSS Information and Data ........................................................... 190 Table 7.2.3-1 Test Evaluation Public Release Data List ....................................................... 191 Table 8.1.1-1 Parameters with definitions unique to QZSS ................................................... 193 Table 8.1.2-1 Parameters with definitions unique to QZSS ................................................... 194 Table 8.1.3-1 Parameters with definitions unique to QZSS ................................................... 195 IS-QZSS Ver. 1.4 1 1 Scope This Interface Specification (IS-QZSS) presents an overview of the Quasi-Zenith Satellite System (QZSS 1 ) being developed by the Japan Aerospace Exploration Agency (JAXA) and defines the interface between the Space Segment (SS) provided by the Quasi-Zenith Satellites (QZS 2 ), and the User Segment (US) of the QZSS. IS-QZSS was prepared to encourage the use of the positioning, navigation and timing services of QZSS which are freely available for peaceful means to anyone who has visibility to one or more QZS. QZSS signals have been designed and developed so as to maximize the interoperability with the NAVSTAR Global Positioning System (GPS) operated by the United States (U.S.) as well as to provide compatibility of QZSS with GPS and other space-based systems that comprise the Global Navigation Satellite System （GNSS）. The QZSS signal design reflected in this document was established through closely collaborated discussion with in the U.S.-Japan GPS QZSS Technical Working Group. IS-QZSS provides general information regarding the QZSS system and services and also covers service performance, QZSS signal characteristics and recommended user algorithms. QZSS is designed to work in conjunction with, and enhance, the civil services of GPS. Therefore, this document makes reference to the public domain GPS interface specification documents listed in Section 2 below. IS-QZSS describes in detail all differences with respect to GPS that user equipment designers must be aware of to make full use of the enhanced capabilities possible when QZSS signals are received in addition to GPS signals. This specification is intended for all users of QZSS and includes information about utilizing the L1C/A, L1C, L1-SAIF, L2C, L5 and LEX signals transmitted by Quasi-Zenith Satellites (QZS). This IS-QZSS document has been updated several times since the publication of the first draft edition due to the progress of the system design and development. In this IS-QZSS Version 1.0 release, the signal types signal strengths, signal structures, and other elements from the previous release of IS-QZSS have been updated. JAXA welcomes and encourages feedback from QZSS users. IS-QZSS will be reviewed and revised in response to valuable user feedback in addition to the progress of the QZSS design, the technology demonstration after the launch of the first QZS, the results of the utilization demonstration, etc., from the viewpoints of manner of operation, handling of data, readability, and others. Upon the release of the next revision of IS-QZSS, the comments of users will again be taken into consideration. 1 QZSS is an abbreviation for Quasi Zenith Satellite System and refers to the system as a whole. 2 QZS is an abbreviation for Quasi Zenith Satellite and refers specifically to these satellites. IS-QZSS Ver. 1.4 2 Application demonstration will be mainly conducted by the private sector. Satellite Positioning Research and Application Center (SPAC) will be a coordinator for user interface among related organizations. Section 3 of IS-QZSS presents an overview of the Quasi-Zenith Satellite System. The availability, geographical coverage and system performance provided by QZSS are introduced in Section 4. Sections 5 to 8 contain the details of the interface specification and signal description. Section 5 specifies the QZSS signal properties including RF characteristics, message structure and data format. Section 6 contains user algorithms to be incorporated in receiver designs. Section 7 provides information regarding obtaining QZSS operational data via the internet. Finally, the differences between QZSS and GPS messages are summarized in Section 8 for the convenience of users. The specification for L1-SAIF signal in Section 4.3.2 “Alert flag, URA and Health Data”, Section 4.3.3.5 “Positioning Accuracy by means of Performance Enhancement Signals”, Section 5.4 “L1-SAIF signal” and Section 6.4 “L1 SAIF Algorithm” are development results by Electronic Navigation Research Institute. And also, the information about “L1-SAIF+ message” in Section 5.4.3.1.2 and 5.4.3.5 reflects the fruits of research and development by Satellite Positioning Research and Application Center. The detailed specification defined the interface will be issued by Satellite Positioning Research and Application Center separately. The specification for the definition of message type for LEX signal in Section 5.7.2.2.2 is development results by Geographical Survey Institute. And detailed specifications for messages type 156 - 255 in Section 5.7.2.2.4 have been issued by Satellite Positioning Research and Application Center (in Section 2 "Applicable Document" (6)). IS-QZSS Ver. 1.4 3 2 Applicable Documents (1) Navstar GPS Space Segment/Navigation User Interface, Interface Specification, IS-GPS-200. Rev. E, June 2010. (2) Navstar GPS Space Segment/User Segment L5 Interfaces, Interface Specification, IS-GPS-705. Rev. A, June 2010. (3) Navstar GPS Space Segment/User Segment L1C Interfaces, Interface Specification, IS-GPS-200. Rev. E, June 2010. (4) International Standards and Recommended Practices, Aeronautical Telecommunications, Annex 10 to the Convention on International Civil Aviation, vol. I, ICAO, Nov. 2002. (5) Minimum Operational Performance Standards for Global Positioning System/Wide Area Augmentation System Airborne Equipment, DO-229C, RTCA, Nov. 2001. (6) SPAC- -100630-15, Quasi-Zenith Satellite System Navigation Service Application Demonstration, Augment Message Specification for QZSS, Satellite Positioning Research and Application Center, July 2011. IS-QZSS Ver. 1.4 4 3 Overview of QZSS The Quasi-Zenith Satellite System (QZSS) is a regional space-based positioning system that uses a constellation of satellites placed in multiple orbital planes. The satellites have the same orbital period as a traditional equatorial geostationary orbit, however, they have a large orbital inclination and therefore move with respect to the Earth. The QZS orbits are also elliptical and are sometimes known as “highly-inclined elliptical orbits” or HEO. The system covers regions in East Asia and Oceania centering on Japan and is designed to enable users in the coverage area to receive QZS signals from a high elevation angle at all times. QZSS enhances GPS services in the following two ways: 1) Availability enhancement (improving the availability of GPS signals) and 2) Performance enhancement (increasing the accuracy and reliability of GPS signals). By broadcasting signals that are similar to and compatible with GPS, QZSS enhances standalone GPS availability for any user that has visibility to, and can track, one or more QZS. This enhancement will be the greatest for users in the region of Japan because the constellation design is optimized for that area. However, users in many other Asia-Pacific areas will also benefit from the enhanced geometric arrangement made possible by QZSS. This increases the area and times at which positioning is possible in both urban and mountainous areas where a portion of the sky is often blocked from view. To ensure interoperability and compatibility with modernized GPS civil signals, the GPS availability enhancement signals transmitted from QZSS satellites use modernized GPS civil signals as a base, transmitting the L1C/A, L1C, L2C and L5 signals. This minimizes changes to specifications and receiver designs. Additionally, L1C and L5 of above signals transmitted by QZSS have interoperability with not only GPS but also Galileo and other GNSS in future multi-GNSS era. QZSS further improves standalone GPS accuracy by means of ranging correction data provided through the transmission of submeter-class performance enhancement signals L1-SAIF and LEX from QZS. It also improves reliability by means of failure monitoring and system health data notifications. QZSS also provides other support data to users to improve GPS satellite acquisition. The QZSS project will be implemented incrementally in accord with the official policy of the Government of Japan released on March 31, 2006 as follows. Phase One: Technical validation and application demonstration will be conducted with the first QZSS satellite. Phase Two: Following the successful completion of Phase One, the 2nd and 3rd QZSS satellites will be launched. Full system operation will be demonstrated. IS-QZSS Ver. 1.4 5 3.1 Overview of QZSS 3.1.1 System Overview QZSS consists of (a) the QZSS Space Segment (SS) comprised of a constellation of Quasi-Zenith Satellites (QZS) orbiting the Earth, and (b) the QZSS Ground Segment (GS) comprised of Monitor Stations (MS), a Master Control Station (MCS), Tracking Control Stations (TCS) and Time Management Station (TMS). A system diagram is provided in Figure 3.1.1-1. QZS signals are transmitted from the QZS and monitored by the MS. The MCS collects the MS monitoring results and estimates and predicts the QZS time and orbit. The MCS also gathers other data as well and generates navigation messages, and uplinks to the QZS via the Tracking Control Station. The Tracking Control Stations constantly monitor the status of the QZS and function in cooperation with the MCS to provide appropriate services as needed. In addition, approximately once per year, the TCS exercise orbital control to ensure that the QZS is maintained in the correct orbital position. Figure 3.1.1-1 System overview 3.1.1.1 Overview of QZSS Space Segment The QZSS Space Segment (SS) consists of initially one satellite, and ultimately three (or more) satellites having the characteristics described below. 3.1.1.1.1 QZSS Constellations The baseline QZSS constellation is comprised of three satellites as illustrated below. All QZS are in orbits that have the same “figure-8” ground track (passing over Southeast Asia, Australia, etc.) as shown in Figure 3.1.1-2 and Figure 3.1.1-4. The orbit tracks of the 3 satellites are shown in Figure 3.1.1-3. IS-QZSS Ver. 1.4 6 Figure 3.1.1-2 QZSS Orbit and Ground Track Diagram for the Three-Satellite Constellation Equator 0 40 80 120 160 320 280 240 200 A r g u m e n t o f L a t it u d e [ d e g ] O r b it a l P la n e C ( R A A N = 9 0 d e g ) O r b it a l P la n e B ( R A A N = 3 3 0 d e g ) RAAN O r b it a l P la n e A ( R A A N = 2 1 0 d e g ) QZS1 QZS3 QZS2 Note1: Tentative for QZS2 and QZS3 43 degree Equator 0 40 80 120 160 320 280 240 200 A r g u m e n t o f L a t it u d e [ d e g ] O r b it a l P la n e C ( R A A N = 9 0 d e g ) O r b it a l P la n e B ( R A A N = 3 3 0 d e g ) RAAN O r b it a l P la n e A ( R A A N = 2 1 0 d e g ) QZS1 QZS3 QZS2 Note1: Tentative for QZS2 and QZS3 43 degree Figure 3.1.1-3 Constellation Orbit Track Diagram (EPOCH=2009/Dec/26/12:00UTC) for the Three-Satellite Constellation IS-QZSS Ver. 1.4 7 3.1.1.1.2 Orbits The parameters defining the QZS nominal orbits are provided below. The satellites have the same orbital period as a traditional equatorial geostationary satellite, however, they have a large orbital inclination so they do not remain in the equatorial plane and therefore move with respect to the Earth. The QZS orbits are also elliptical and are sometimes known as “highly-inclined elliptical orbits” or HEO. The QZS will orbit somewhat further from the Earth in the Northern Hemisphere than in the Southern Hemisphere. These orbits result in a longer period of high elevation angle service for the region of Japan. Ultimately a single satellite will be deployed in each of the three orbital planes, thereby providing continuous coverage at high elevation angles for the primary service areas (including all Japanese territory). 3.1.1.1.2.1 Semi-Major Axis (a) a = 42164 km (average) 3.1.1.1.2.2 Eccentricity (e) e = 0.075 +/- 0.015 3.1.1.1.2.3 Orbital inclination (i) i = 43°+/-4° 3.1.1.1.2.4 Right Ascension of Ascending Node (Ω) With the argument of perigee, the right ascension of ascending node for each satellite is designed to maintain the central longitude of the ground track (see Section 3.1.1.1.2.6). The initial right ascension of ascending node of Quasi-Zenith Satellite-1 (QZS-1) Ω 0 is set at about 195[deg]. For the 3-satellites QZSS constellation, the initial right ascension of ascending node of QZS-2 & 3 is going to be set at that of QZS-1 +/- 120[deg]. 3.1.1.1.2.5 Argument of Perigee (ω) ω = 270°+/-2° 3.1.1.1.2.6 Central Longitude of Ground Trace The central longitude of ground trace is the center of the 8-figure ground trace, and is the center of two longitudes of ascending and descending. The longitude value is maintained 135° East +/- 5° . IS-QZSS Ver. 1.4 8 3.1.1.1.3 QZS orbit Ground Tracks Figure 3.1.1-4 shows the QZS orbit ground tracks (See Table 3.1.1-1 for calculation condition). Figure 3.1.1-4 QZS Orbit Ground Tracks Table 3.1.1-1 Calculation condition for QZS-1 nominal orbit No. Item Setting 1 Epoch 26 Dec. 2009, 12:00:00 (UTC) 2 Semi-Major Axis [km] 42164.16945 3 Eccentricity 0.075 4 Orbital inclination [deg] 43.0 5 Right Ascension of Ascending Node [deg] 195.0 6 Argument of Perigee [deg] 270.0 7 Mean Anomaly [deg] 305.0 3.1.1.1.4 QZS Figure 3.1.1-5 shows an illustration of a QZS. It has two deployable solar cell array panels, an L-band transmission antenna (L-ANT), an L1-SAIF transmission antenna (LS-ANT), TTC antennas, and a Ku-band Time Transfer Antenna (Ku-ANT). The QZS utilizes fixed (non-steerable) antennas mounted on one side of the spacecraft. The QZS attitude is controlled to ensure that these antennas always point toward the center of the Earth. Yaw steering controls the orientation of the solar cell arrays to optimize reception of sunlight. The L-ANT is made up of a helical antenna array. The gain curve formed by this array is designed to provide signals with constant power levels at any location on the ground by compensating for the Earth’s surface shape. IS-QZSS Ver. 1.4 9 Figure 3.1.1-5 QZS The QZS includes the equipment shown in Figure 3.1.1-6 that is used to generate and transmit QZS signals. QZS signals comprise a carrier wave that uses a rubidium atomic clock as a frequency reference and that is modulated by PRN codes and navigation messages generated by the MCS. These signals are transmitted toward the Earth from the L-ANT and LS-ANT. Time Comparison Unit Time Transfer System RF portion ＲｂAtomic Clock Time Keeping Unit Synthesizer Navigation Operation Computer Modulator Amplifier Laser Reflector Rb Atomic Clock Sine Wave Signal of Two Way Satellite Time and Frequency Transfer Navigation Signal Time Keeping Unit Synthesizer Navigation Onboard Computer Modulator Amplifier MUX Time Comparison Unit Time Transfer System RF portion Ku-Ant L-Ant Uploaded Data (including Remote Synchronization Signal) Baseband Signal (Navigation Message + PRN Code) Control Phase Error QZS L1-SAIF-Ant TT&C TT&C Subsystem TLM Navigation Message, CMD Figure 3.1.1-6 QZS Block Diagram 3.1.1.2 Overview of Ground Segment The QZSS Ground Segment consists of multiple Earth-based stations. These comprise Monitor Stations (MS) that are widely distributed and observe QZS and GPS signals on the ground; a Master Control Station (MCS) that collects the results of monitoring from all of the MS, estimates and predicts QZSS and GPS clock offsets and orbits, generates navigation messages, etc.; Tracking Control Stations that uplink navigation messages and monitor QZS status, and the Time Management Station (TMS) for time transfer. IS-QZSS Ver. 1.4 10 There are nine MS dispersed throughout the area from which QZS signals can be received (Refer to Figure 3.1.1-7). The MCS (Refer to Figure 3.1.1-8) and TMS are located in Japan. The rough locations of each Ground Stations are shown in Table 3.1.1-2. -90 -60 -30 0 30 60 90 0 30 60 90 120 150 180 210 240 270 300 330 360 L a t i t u d e Longitude Hawaii Guam Canberra Bangalore Sarobetsu Koganei Tsukuba Okinawa Chichijima Bangkok Figure 3.1.1-7 Mapping of Ground Stations Table 3.1.1-2 Location of Ground Station No. Place Location (Longitude and Latitude) 1 Koganei East longitude 139.4882° North latitude 35.7078° 2 Sarobetsu East longitude 141.7489° North latitude 45.1636° 3 Okinawa East longitude 127.8444° North latitude 26.4986° 4 Chichi-Jima East longitude 142.2154° North latitude 27.0792° 5 Hawaii West longitude 159.6650° North latitude 22.1262° 6 Guam East longitude 144.7948° North latitude 13.4774° 7 Bangkok East longitude 100.6130° North latitude 14.0823° 8 Bangalore East longitude 77.5116° North latitude 13.0343° 9 Canberra East longitude 149.0104° South latitude 35.3160° -90 -60 -30 0 30 60 90 0 30 60 90 120 150 180 210 240 270 300 330 360 Longitude L a t i t u d e 系列1 系列2 Master Control Station QZSS Monitor Station Tracking Control Station Hawaii Guam Canbera India Sarobetsu Koganei Tsukuba Okinawa Chichijima Thailand IS-QZSS Ver. 1.4 11 Figure 3.1.1-8 MCS Several Tracking Control Stations are strategically positioned at locations that enable continuous monitoring and control of the QZS. Two Tracking Control Stations are constructed in the Okinawa Tracking and Communication Station for the first development phase of Quasi-Zenith Satellite System. Figure 3.1.1-9 shows the type of TTC antenna with which each Tracking Control Station is equipped. Figure 3.1.1-9 TTC Antenna IS-QZSS Ver. 1.4 12 3.1.2 Operation 3.1.2.1 Data 3.1.2.1.1 Data Flow Figure 3.1.2-1 shows an overview of the QZSS data flow. (1) QZS signals and signals from other GNSS are received by the Monitor Stations (MS). (2) The results of monitoring by the MS are sent to the Master Control Station (MCS) where QZSS and other GNSS orbits and times are estimated and propagated to predict future satellite positions and system times. (3) Based on the results of orbit and time estimates and predictions, navigation messages are generated and sent to the Tracking Control Stations. (4) At the Tracking Control Stations, the navigation messages are uploaded to the QZS On-board Control Computer by way of the Telemetry Command Subsystem. (5) On-board the QZS, a signal with the navigation messages superimposed are generated and transmitted to the Earth via the L-band transmission antenna and the L1-SAIF transmission antenna. Figure 3.1.2-1 System data flow IS-QZSS Ver. 1.4 13 3.1.2.1.2 Navigation Message Update and Uplink The navigation messages in the QZS signals, except the L1-SAIF and LEX signals, are updated with the timing shown in Figure 3.1.2-2. For this purpose, QZSS uplinks the appropriate navigation messages at the necessary intervals by way of the Tracking Control Stations. Ephemeris data and Almanac data, excluding SV Clock parameters and Differential data, are updated every 3600 seconds. SV Clock parameters are updated every 900 seconds. URA of the signals are updated every 30 seconds for L1C/A, every 18 seconds for L1C, every 48 seconds for L2C and every 24 seconds for L5. Other information are depends on navigation pattern table (see Section 7.2.4.3). Orbit Parameters of Ephemeris data is valid for 7200 seconds, and SV Clock Parameters are valid for 1800 seconds. The navigation messages of the L1-SAIF and LEX signals are uploaded from MCS, superimposed upon navigation signals on OZS and transmitted to the Earth continuously. 1week = 604800s 3600s Ti me of Week 00:00:00 (Week Number = n) 900s (1)Ephemeris, Almanac other than (2)(3) (2)SV Clock Parameter (3)Differential Data 3600s 3600s 300s 300s 300s 300s 300s 300s TOW 00:00:00 (WN = n+1) 900s 900s 900s 900s 900s 900s 900s 900s 900s 900s 900s 900s Figure 3.1.2-2 An example of the update timing of the navigation message IS-QZSS Ver. 1.4 14 Further Navigation message timing details are provided in Figure 3.1.2-3. L1C/A Overall message Ephemeris, Clock Overall message Ephemeris, Clock at 15-min intervals time URA INDEX, NMCT, AODO 5min(300s) at 15-min intervals EDC, CDC URA INDEX Hour (Overall message update) Hour (Overall message update) Overall message Ephemeris, Clock at 15-min intervals EDC, CDC URA INDEX Overall message Ephemeris, Clock at 15-min intervals EDC, CDC URA INDEX L2C L5 L1C at 5-min intervals at 5-min intervals at 5-min intervals at 30-s intervals at 48-s intervals at 24-s intervals at 18-s intervals Figure 3.1.2-3 An example of uplink timing of the navigation message 3.1.2.1.3 Uplink of "Alert" Flag, URA, Health Data and Differential Data The “Alert” flag, URA, Health data and differential data described below are transmitted to the user by QZSS on the L1C/A, L1C, L2C, L5 and LEX signals. See Section 5.4 for information regarding the L1-SAIF signal. 3.1.2.1.3.1 "Alert" flag (on L1C/A, L1C, L2C, L5 and LEX) QZSS monitors QZS signals and status and, once per second, makes a determination as to whether or not the Signal-In-Space (SIS) accuracy of any QZS signal is worse than 9.65 [m] and whether there is any detected problem with the QZS. If the determination is that a QZS signal is not suitable for use, the user is notified within the time limits specified for each signal in Section 4.3.2.2, of the detection of the problem via the corresponding “Alert” flag. Also when the QZS is in its maintenance operations which are described in Section 3.1.2.2.1.1 and Section 3.1.2.2.1.2, the “Alert” flag in its navigation message is set to indicate it to users and to notify to users that the QZS signal cannot be used. IS-QZSS Ver. 1.4 15 3.1.2.1.3.2 URA (on L1C/A, L1C, L2C, L5 and LEX) URA stands for "User Range Accuracy”. The SIS accuracy, quantified as URA, is reported in a timely manner when the Ephemeris data being provided to the user and the SV clock parameters are used. QZSS monitors the QZS signals and, once per second, estimates the SIS accuracy of the signals in the direction of the QZS Line of Sight vector. The data are uploaded to the QZS within the time limits specified for each signal in Section 4.3.2.2, and the absolute value of the estimated URA (SIS accuracy) will be sent to the user within 30 seconds of the corresponding QZS signal transmission from MCS. 3.1.2.1.3.3 Health Data (on L1C/A, L1C, L2C, L5 and LEX) QZSS monitors the QZS signals and QZS status and, once per second, makes a determination as to power level, modulation status and whether or not any message errors have occurred. At the same time, QZSS also monitors the signals of SVs of other GNSS systems and judges power level and modulation status, and, once per second estimates the SIS accuracy of these signals. The data are uploaded to the QZS immediately at the time when abnormal events are detected or confirmed that events are ended and return to nominal condition, therefore the users will be notified of the results within the seconds, which is specified in Section 4.3.2.2, of the corresponding QZS and other SV signal transmissions. 3.1.2.1.3.4 NMCT (on L1C/A), EDC and CDC (on L1C, L2C and L5) NMCT stands for "Navigation Message Correction Table”. EDC stands for "Ephemeris Differential Correction”. CDC stands for "Clock Differential Correction”. By using the differential data provided by QZSS in these three correction terms, user receivers are able to mathematically remove most of the errors inherent in the Ephemeris data and SV clock parameters. QZSS monitors the QZS signals and the signals of other GNSS systems and, once per second, estimates the SIS error in the direction of the Line of Sight vector. The results of these estimates are uploaded to the QZS every 30 seconds for NMCT, and 300 seconds for EDC and CDC, as differential data. 3.1.2.1.3.5 UDRA and UDRA dt d (on L1C, L2C and L5) UDRA stands for "User Differential Range Accuracy". This value is used together with its time derivative, UDRA dt d , to enable users to determine the SIS accuracy after correction with the EDC and CDC. This indicates the accuracy of the SIS error estimates calculated by the QZSS MCS in the direction of the Line of Sight vector for QZS signals and the signals of other GNSS systems. The value is uploaded to the QZS every 300 seconds. 3.1.2.1.3.6 NSC switching NSC stands for "Non-Standard Code". The NSC is an invalid pseudo-random noise (PRN) code sequence (i.e., one that is not valid for use by any GNSS receiver). An operator of QZSS may switch manually from transmitting its normal ranging PRN code to transmitting the NSC to protect users under a system error. At such times, the transmission of NSC will ensure that users are not able to receive signals IS-QZSS Ver. 1.4 16 from the affected QZS. The time to switch to NSC from standard PRN code is within 15 seconds. URA broadcast Error Occurs ／maintenance Alert flag broadcast investigation Switch to NSC ・URA exceeds value which is assured in this specification (Automatically) ・Actual URA exceeds index which has been broadcasted (Automatically) ・SIS accuracy exceeds the range by the URA’s bit length (Automatically) ・The QZS can not be used because of the maintenance (Manually) ・If corrected→Alert canceled (Manually) ・If corrected→Alert canceled (Manually), switch to standard code (Manually) ・If not corrected→broadcast suspended (Manually) ・ O t h e r s y s t e m e r r o r h a s o c c u r r e d ( M a n u a l l y ) investigation URA broadcast Error Occurs ／maintenance Alert flag broadcast investigation Switch to NSC ・URA exceeds value which is assured in this specification (Automatically) ・Actual URA exceeds index which has been broadcasted (Automatically) ・SIS accuracy exceeds the range by the URA’s bit length (Automatically) ・The QZS can not be used because of the maintenance (Manually) ・If corrected→Alert canceled (Manually) ・If corrected→Alert canceled (Manually), switch to standard code (Manually) ・If not corrected→broadcast suspended (Manually) ・ O t h e r s y s t e m e r r o r h a s o c c u r r e d ( M a n u a l l y ) investigation Figure 3.1.2-4 Relationship between "Alert" flag and URA/NSC switching 3.1.2.2 Maintenance, Failure, Restoration and Testing 3.1.2.2.1 Satellite System Maintenance Two or more QZS will never halt service at the same time due to the orbit maintenance or attitude maintenance described below. 3.1.2.2.1.1 Orbit Maintenance The QZS orbit is affected by forces of various types (the Earth's gravitation, the solar radiation and etc.). As a result, it will slowly drift from its intended orbit. For this reason, QZSS conducts orbit maintenance once every 150 days (average). Service is halted for up to two days during orbit maintenance. The notification way of the orbit maintenance information to the users are referred to chapter 7.2.1. Moreover, immediately prior to orbit maintenance, the "Alert" flag is set to "1". When orbit maintenance is complete, the "Alert" flag is cleared (set to “0”). As a result of orbit maintenance, the QZS orbit will be maintained within the range shown in Figure 3.1.2-5. IS-QZSS Ver. 1.4 17 Figure 3.1.2-5 Range of Orbital Maintenance 3.1.2.2.1.2 Momentum Management The attitude of the QZS is affected primarily by the solar radiation pressure. The solar radiation pressure is absorbed by reaction wheels on the QZS to prevent it from affecting the QZS attitude. However, once per more than 30 days (average 40 days), momentum management (in which this angular momentum is unloaded) must be performed. During this momentum unloading process, service will be halted for a period of up to one day. Users will be notified in advance regarding the occurrence of the unloading process through the medium of the Internet, etc. Moreover, immediately before unloading, the "Alert" flag is set to "1". When unloading is complete, the "Alert" flag is cleared (set to “0”). 3.1.2.2.1.3 QZS failure and restoration In the event that a certain QZS experiences an unexpected satellite-wide failure, notification of the failure of that QZS is sent from another QZS by means of the Navigation message (see Section 5.1.2.1.3). Transmission of the QZS signals from the failed QZS is halted or switched over to NSC. In the event that one of the sub-systems in a certain QZS fails, notification of the failure and repair of that sub-system is sent by means of the Navigation message (see Section 5.1.2.1.3) using signals that include identification of any remaining valid signals of that QZS. In addition, users are notified regarding the status of these systems through the medium of the Internet, etc shown in Section 7 of “PROVISION OF QZSS OPERATIONAL INFORMATION AND DATA VIA THE INTERNET”. 3.1.2.2.2 Ground Segment system maintenance Ground Segment maintenance will be performed in a manner that does not adversely affect QZSS availability. : Nominal (See Section 3.1.1.1.2) : Nominal longitude of ascending +/- 5[deg.] : Nominal Inclination +/- 4[deg.] IS-QZSS Ver. 1.4 18 3.1.2.2.3 Testing Depending on the nature of the tests, it may not always be possible to provide the specified positioning performance to users during certain QZSS tests. At such times, the standard transmitted PRN codes may be switched to NSC in order to protect users. In such cases, users will generally be given advance notice through the medium of the Internet, etc shown in Section 7 of “PROVISION OF QZSS OPERATIONAL INFORMATION AND DATA VIA THE INTERNET” regarding the period of time during which such testing will occur. 3.1.3 Signals transmitted by QZS = QZS Signals 3.1.3.1 Types of Signals Transmitted by QZS QZSS satellites transmit six positioning signals: L1C/A signal, L1-SAIF signal, L1C signal, L2C signal, LEX signal and L5 signal. Four of these -- L1C/A, L1C, L2C and L5 -- are known as positioning availability enhancement signals (or simply availability enhancement signals) in the sense that they complement the existing Global Navigation Satellite System (GNSS). The remaining two signals -- L1-SAIF and LEX -- are known as positioning performance enhancement signals (or simply performance enhancement signals) in the sense that they enhance performance through the transmission of existing GNSS differential data and integrity data concerning GNSS signals as determined by QZSS. 3.1.3.2 Spectrum of QZS Signals The six positioning signals transmitted by QZS have four center frequencies. With the reference frequency set to MHz f 23 . 10 0  , these carrier frequencies are 0 154 f  for L1, 0 125 f  for LEX, 0 120 f  for L2, 0 115 f  for L5. Figure 3.1.3-1 shows the power spectral density of the six QZS signals versus frequency. Note that this is the power spectral density at the input of user antenna on the ground. -260 -255 -250 -245 -240 -235 -230 -225 -220 -215 1125.30 1176.45 1227.60 1278.75 1329.90 1381.05 1432.20 -260 -255 -250 -245 -240 -235 -230 -225 -220 -215 1329.90 1381.05 1432.20 1483.35 1534.50 1585.65 1636.80 Frequency (MHz) P o w e r S p e c t r a l D e n s i t y ( d B ( W / H z ) ) Figure 3.1.3-1 Power Spectral Density of QZS Signals L5 L2C LEX L1C L1C/A L1-SAIF L5 center frequency: 1176.45 MHz L2 center frequency: 1227.60 MHz LEX center frequency: 1278.5 MHz L１ center frequency: 1575.42 MHz IS-QZSS Ver. 1.4 19 3.1.3.3 General Specifications for QZS Signals Table 3.1.3-1 shows the general specifications for QZS signals. Table 3.1.3-1 General Specifications for QZS Signals Signal name Center frequency I/Q channel identification Spreading frequency L1C/A * 1575.42MHz － 0.1 × f 0 L1C * Data channel 0.1 × f 0 Pilot channel 0.1 × f 0 L1-SAIF － 0.1 × f 0 L2C * 1227.60MHz － (2 channels time multiplexed) 0.1 × f 0 L5 * 1176.45MHz I channel 1 × f 0 Q channel 1 × f 0 LEX 1278.75MHz － 0.5 × f 0 *GPS availability enhancement signal IS-QZSS Ver. 1.4 20 3.1.3.4 QZS Signal Doppler The Doppler values for QZS signals received at eight reference locations equals to Relative velocity of signals (Change rate of distance) between each city and QZS-1 (shown in Figure 3.1.3-2) multiplied by the Doppler coefficients for each positioning signal frequency (Center frequency/Speed of light) (listed in Table 3.1.3-2). In Figure 3.1.3-2, the gaps in the plots of relative velocity correspond to times when the QZS is below 10 degrees elevation angle for the corresponding location. The upper and lower solid lines represent the upper and lower ranges of the relative velocity, respectively. -600 -400 -200 0 200 400 600 0 3 6 9 12 15 18 21 24 R e l a t i v e V e l o c i t y ( m / s e c ) Time (Hr) -600 -400 -200 0 200 400 600 0 3 6 9 12 15 18 21 24 R e l a t i v e V e l o c i t y ( m / s e c ) Time (Hr) Wakkanai (Hokkaido, Japan) Tokyo -600 -400 -200 0 200 400 600 0 3 6 9 12 15 18 21 24 R e l a t i v e V e l o c i t y ( m / s e c ) Time (Hr) -600 -400 -200 0 200 400 600 0 3 6 9 12 15 18 21 24 R e l a t i v e V e l o c i t y ( m / s e c ) Time (Hr) Okinawa Seoul -600 -400 -200 0 200 400 600 0 3 6 9 12 15 18 21 24 R e l a t i v e V e l o c i t y ( m / s e c ) Time (Hr) -600 -400 -200 0 200 400 600 0 3 6 9 12 15 18 21 24 R e l a t i v e V e l o c i t y ( m / s e c ) Time (Hr) Bangkok Singapore -600 -400 -200 0 200 400 600 0 3 6 9 12 15 18 21 24 R e l a t i v e V e l o c i t y ( m / s e c ) Time (Hr) -600 -400 -200 0 200 400 600 0 3 6 9 12 15 18 21 24 R e l a t i v e V e l o c i t y ( m / s e c ) Time (Hr) Sydney Perth Figure 3.1.3-2 Relative velocity of signals (Change rate of distance) between each city and QZS-1 (See Table 3.1.1-1 for calculation condition. Observation EPOCH = 2009/Dec/26/12:00UTC. Horizontal axis means elapsed time from EPOCH.) IS-QZSS Ver. 1.4 21 Table 3.1.3-2 Doppler coefficients for signals Signal Doppler scale L1C/A, L1C, L1-SAIF 5.3 L2C 4.1 L5 3.9 LEX 4.3 IS-QZSS Ver. 1.4 22 3.1.3.5 Elevation and Azimuthal Angles Plots of angle of elevation and azimuth angles to QZS for eight reference locations are shown in Figure 3.1.3-3 as they vary over the course of the QZS orbit. 60 30 10 E W N S 60 30 10 E W N S Wakkanai (Hokkaido, Japan) Tokyo 60 30 10 E W N S 60 30 10 E W N S Okinawa Seoul 60 30 10 E W N S 60 30 10 E W N S Bangkok Singapore 60 30 10 E W N S 60 30 10 E W N S Sydney Perth Figure 3.1.3-3 Elevation and Azimuthal angles for each city (See Table 3.1.1-1 for calculation condition. Observation EPOCH = 2009/Dec/26/12:00 UTC) IS-QZSS Ver. 1.4 23 3.1.3.6 Received Signal Power Level at Reference Locations The User Received Power Levels for each QZS signal at eight reference locations are shown in Figure 3.1.3-4 as a function of time as they vary over the course of the QZS orbit. In Figure 3.1.3-4, the gaps in the plots of signal power correspond to times when the QZS is below 10 degrees elevation angle for the corresponding location. -162 -160 -158 -156 -154 -152 -150 0 3 6 9 12 15 18 21 24 U R P ( d B W ) Time (Hr) L5 LEX SAIF L1C L1C/A L2C -162 -160 -158 -156 -154 -152 -150 0 3 6 9 12 15 18 21 24 U R P ( d B W ) Time (Hr) L5 LEX SAIF L1C L1C/A L2C Wakkanai (Hokkaido, Japan) Tokyo -162 -160 -158 -156 -154 -152 -150 0 3 6 9 12 15 18 21 24 U R P ( d B W ) Time (Hr) L1C/A L2C L5 LEX SAIF L1C -162 -160 -158 -156 -154 -152 -150 0 3 6 9 12 15 18 21 24 U R P ( d B W ) Time (Hr) L5 LEX SAIF L1C L1C/A L2C Okinawa Seoul -162 -160 -158 -156 -154 -152 -150 0 3 6 9 12 15 18 21 24 U R P ( d B W ) Time (Hr) L5 LEX L1C/A L2C SAIF L1C -162 -160 -158 -156 -154 -152 -150 0 3 6 9 12 15 18 21 24 U R P ( d B W ) Time (Hr) L5 LEX SAIF L1C L1C/A L2C Bangkok Singapore -162 -160 -158 -156 -154 -152 -150 0 3 6 9 12 15 18 21 24 U R P ( d B W ) Time (Hr) L5 LEX SAIF L1C L1C/A L2C -162 -160 -158 -156 -154 -152 -150 0 3 6 9 12 15 18 21 24 U R P ( d B W ) Time (Hr) L5 LEX SAIF L1C L1C/A L2C Sydney Perth Figure 3.1.3-4 Changes of received signal power level for each city (See Table 3.1.1-1 for calculation condition. Observation EPOCH = 2009/Dec/26/ 12:00 UTC. Horizontal axis means elapsed time from EPOCH.) IS-QZSS Ver. 1.4 24 3.1.4 Time System and Coordinate System 3.1.4.1 Time System The QZSS time system is called QZSST and has the following characteristics. QZSST conforms to UTC (NICT) and the offset with respect to the GPS time system, GPST, is controlled. (1) One-second length The length of one second is identical to International Atomic Time (TAI). It is also the same for GPS and Galileo. (2) Integer second offset for TAI The integer second offset for TAI is the same as for GPS and TAI is always 19 seconds ahead of QZSST. (3) Starting point of Week Number for QZSST The starting point of the Week Number for QZSST is identical to GPST. Therefore, this parameter is just referred to as “Week Number” (and not specified as corresponding to QZSST or GPST). 3.1.4.2 Coordinate System The QZSS geodetic coordinate system is known as the Japan satellite navigation Geodetic System (JGS). This coordinate system is defined as follows so as to approach the International Terrestrial Reference System (ITRS). (a) Origin: Same as defined for the GRS80 3 ellipsoid (earth’s center of mass) The geometrical center of the GRS80 ellipsoid is established as the Earth’s center of mass. (b) Z axis: International Earth Rotation and Reference Systems Service (IERS 4 ) pole direction (c) X-axis: Direction of intersection of Greenwich Meridian and equatorial plane containing origin and Z-axis (d) Y-axis: Direction formed by the right-handed fixed geocentric coordinate system 3 Background: Abbreviation for Geodetic Reference System 1980. GRS80 defines the shape of the earth, gravitational constants, angular velocity and other physical constants and computational expressions that were adopted in 1979 by the International Association of Geodesy (IAG) and the International Union of Geodesy and Geophysics (IUGG). In GRS80, the shape of the ellipsoid, the direction of axes and the earth’s center of gravity were established and define a reference ellipsoid known as the GRS80 ellipsoid. 4 Background: Abbreviation for International Earth Rotation and Reference Systems Service. IERS is an international organization formed with the objective of defining and maintaining a common global standard coordinate system, determining global time and so on. Its parent organizations are the International Union of Geodesy and Geophysics (IUGG) and the International Association of Geodesy (IAG). IS-QZSS Ver. 1.4 25 3.2 Interface with Other Systems 3.2.1 QZSS Time System Relative to Other GNSS 3.2.1.1 Interface with GPS The SV clocks for QZS and GPS satellites are both controlled with respect to the offset from the GPS time scale (GPST). The size of the offset is corrected by the SV clock parameter included in the Navigation message that is transmitted by each satellite. 3.2.1.2 Interface with Galileo TBD GALILEO satellites’ Clocks UTC GPST(GPS-TIME) TAI Steered <50ns,28ns(2-sigma) S t e e r e d < 5 0 n s ( m o d u l o 1 s ) UTC(USNO) GGTO broadcasted on both GPS- L1C and GALILEO GPS SV Clock relative to GPST broadcasted on GPS signal GALILEO SV Clock relative to GST broadcasted on GALILEO signal UTC(NICT) GST（GALILEO-TIME） Q ZSST（Q ZS-TIM E） GPS satellites’ Clocks QZS satellites’ Clocks QZS SV Clock relative to GPST broadcasted on QZS signal < 5 n s ( 2 - s i g m a ) N o r m a l i z e d f r e q u e n c y a c c u r a c y G S T r e l a t i v e t o U T C < 3 x 1 0 ^ - 1 3 0s 19s Figure 3.2.1-1 Diagram of Time System Relationships between QZSS, GPS and Galileo 3.2.2 QZSS Coordinate System Relative to Other GNSS The GPS coordinate system (WGS84) and the Galileo coordinate system have been prepared so as to approach ITRS. Accordingly, under the definition of JGS in Section 3.1.4, all systems are operated so the differences are maintained as specified in Section 4.3.3.2.2. Figure 3.2.2-1 shows a conceptual diagram of the relationships between past and future geodetic coordinate systems. Note that as time moves on, all systems are expected to converge toward ITRS. IS-QZSS Ver. 1.4 26 ITRS ITRS ITRF xx ITRF xx WGS84 WGS84 QZSS Frame QZSS Frame Galileo Frame Galileo Frame time d i f f e r e n c e ITRS ITRS ITRF xx ITRF xx WGS84 WGS84 QZSS Frame QZSS Frame Galileo Frame Galileo Frame time d i f f e r e n c e Figure 3.2.2-1 Convergence of Geodetic Coordinate Systems IS-QZSS Ver. 1.4 27 4 QZSS Coverage, Availability and Performance 4.1 QZSS Service Area 4.1.1 Single QZS Coverage Area Figure 4.1.1-1 and Figure 4.1.1-2 show the availability (the percentage of time during which the specified minimum elevation angle condition is fulfilled) of a single QZS satellite across the surface of the Earth. Figure 4.1.1-1 Percentage of Time during which a Single QZS can be seen at an Elevation Angle of 10° or more Figure 4.1.1-2 Percentage of Time during which a Single QZS can be seen at an Elevation Angle of 60° or more IS-QZSS Ver. 1.4 28 4.1.2 QZSS Coverage Area Figure 4.1.2-1 and Figure 4.1.2-2 show the availability (the percentage of time during which the specified minimum elevation angle condition is fulfilled) of a single QZS across the surface of the Earth due to the QZSS constellation. For the 3-satellite QZSS constellation, at least one QZS is available 100% of the time not only in Japan but in almost all parts of Southeast Asia and Oceania at an elevation angle of 10° or more. In Japan, at least one QZS is available 100% of the time at an elevation angle of 60° or more. Figure 4.1.2-1 Percentage of Time during which at least One QZS in the 3-satellite QZSS constellation can be seen at an Elevation Angle of 10° or more Figure 4.1.2-2 Percentage of Time during which at least One QZS in the 3-satellite QZSS constellation can be seen at an Elevation Angle of 60° or more IS-QZSS Ver. 1.4 29 4.1.3 Elevation Angle Variation for QZSS Constellation The variation of QZS elevation angles for the 3-satellite QZSS constellation at eight reference locations is shown in Figure 4.1.3-1 as a function of time as they vary over the course of the QZS orbit. QZSS Elevation Angle Profile @Wakkanai 0 10 20 30 40 50 60 70 80 90 0 3 6 9 12 15 18 21 24 Time(Hr) E l e v a t i o n A n g l e ( d e g ) QZS1 QZS2 QZS3 QZSS Elevation Angle Profile @Tokyo 0 10 20 30 40 50 60 70 80 90 0 3 6 9 12 15 18 21 24 Time(Hr) E l e v a t i o n A n g l e ( d e g ) QZS1 QZS2 QZS3 Wakkanai (Hokkaido, Japan) Tokyo QZSS Elevation Angle Profile @Okinawa 0 10 20 30 40 50 60 70 80 90 0 3 6 9 12 15 18 21 24 Time(Hr) E l e v a t i o n A n g l e ( d e g ) QZS1 QZS2 QZS3 QZSS Elevation Angle Profile @Soul 0 10 20 30 40 50 60 70 80 90 0 3 6 9 12 15 18 21 24 Time(Hr) E l e v a t i o n A n g l e ( d e g ) QZS1 QZS2 QZS3 Okinawa Seoul QZSS Elevation Angle Profile @Bangkok 0 10 20 30 40 50 60 70 80 90 0 3 6 9 12 15 18 21 24 Time(Hr) E l e v a t i o n A n g l e ( d e g ) QZS1 QZS2 QZS3 QZSS Elevation Angle Profile @Singapore 0 10 20 30 40 50 60 70 80 90 0 3 6 9 12 15 18 21 24 Time(Hr) E l e v a t i o n A n g l e ( d e g ) QZS1 QZS2 QZS3 Bangkok Singapore QZSS Elevation Angle Profile @Sydney 0 10 20 30 40 50 60 70 80 90 0 3 6 9 12 15 18 21 24 Time(Hr) E l e v a t i o n A n g l e ( d e g ) QZS1 QZS2 QZS3 QZSS Elevation Angle Profile @Perth 0 10 20 30 40 50 60 70 80 90 0 3 6 9 12 15 18 21 24 Time(Hr) E l e v a t i o n A n g l e ( d e g ) QZS1 QZS2 QZS3 Sydney Perth Figure 4.1.3-1 Variation of QZSS Constellation (for 3 satellites) Elevation Angles for eight cities (See Table 3.1.1-1 for calculation condition of QZS-1. For QZS-2 and 3, we assumed the right ascension of ascending node is +/- 120 deg from that value of QZS-1. Observation EPOCH = 2009/Dec/26/12:00UTC Horizontal axis means elapsed time from EPOCH.) IS-QZSS Ver. 1.4 30 4.1.4 QZSS constellation availability For the 3-satellite QZSS constellation, Figure 4.1.4-1 shows the average number of QZS satellites visible from the Earth’s surface. Note that two or more satellites are always visible not only from Japan but also from virtually every region of Southeast Asia and Oceania as well. Figure 4.1.4-1 Average Number of QZS Satellites that can be seen at an Elevation Angle of 10° or more with the 3-satellite QZSS Constellation 4.1.5 Target Regions for Ionospheric Parameters Transmitted by QZS Each QZS transmits ionospheric parameters that are effective in the geographical regions shown in Figure 4.1.5-1. The accuracy of these parameters is detailed in Section 4.3.3.3. These ionospheric parameters should not be used in regions other than those target regions shown in Figure 4.1.5-1. Instead, ionospheric parameters transmitted by GPS, or GPS ionospheric parameters retransmitted by the QZS should be used outside of the target regions. Figure 4.1.5-1 Target Regions for Ionospheric Parameters Transmitted by QZS IS-QZSS Ver. 1.4 31 4.1.6 Availability Improvement when QZSS and Galileo are Combined with GPS Figure 4.1.6-1 (1/2) and Figure 4.1.6-1 (2/2) show the improvement in GNSS availability when QZSS and Galileo are combined with the existing GPS constellation (as of NOV 2006). Each of the two figures includes the cases of GPS alone, GPS with QZSS and GPS with QZSS and Galileo. Figure 4.1.6-1 (1/2) and Figure 4.1.6-1 (2/2) provide plots of the percentage of time when the Position Dilution of Precision (PDOP) is less than 6 for GNSS receiver mask angles of 20° and 40°, respectively. Figure 4.1.6-2 show the average number of visible satellites for GNSS receiver mask angles of 10°, 20° and 40°, respectively. IS-QZSS Ver. 1.4 32 GPS (mask angle 20°) QZS + GPS (mask angle 20°) QZS + GPS + Galileo (mask angle 20°) Figure 4.1.6-1(1/2) Percentage of Time when PDOP < 6 for an Elevation Angle Mask of 20° IS-QZSS Ver. 1.4 33 GPS (mask angle 40°) QZS + GPS (mask angle 40°) QZS + GPS + Galileo (mask angle 40°) Figure 4.1.6-1(2/2) Percentage of Time when PDOP < 6 for an Elevation Angle Mask of 40° IS-QZSS Ver. 1.4 34 GPS (mask angle 10°) QZS + GPS (mask angle 10°) QZS + GPS + Galileo (mask angle 10°) Figure 4.1.6-2 (1/3) Average Number of Visible Satellites for an Elevation Angle Mask of 10° IS-QZSS Ver. 1.4 35 20G GPS (mask angle 20°) 20QG QZS + GPS (mask angle 20°) 20QGG QZS + GPS + Galileo (mask angle 20°) Figure 4.1.6-2 (2/3) Average Number of Visible Satellites for an Elevation Angle Mask of 20° IS-QZSS Ver. 1.4 36 40G GPS (mask angle 40°) 40QG QZS + GPS (mask angle 40°) 40QGG QZS + GPS + Galileo (mask angle 40°) Figure 4.1.6-2 (3/3) Average Number of Visible Satellites for an Elevation Angle Mask of 40° IS-QZSS Ver. 1.4 37 4.2 Service Availability Each QZS transmits positioning signals 24 hours a day, 365 days a year. However, the time of day during which a particular QZS satellite is visible to a given location varies with the date. 4.2.1 The fixed initial right ascension of ascending node depending on the launch time Because the initial right ascension of ascending node was fixed depending on the exact launch time, the visibility time was also fixed after the launch. For orbital calculation after the QZS-1 launch, the longitude of the ascending node at weekly epoch would be published as a QZSS almanac via "QZSS Website for Operational Information and Data" in Section 7.1. The visibility time from each location can be seen in Figure 4.2.1-1 (the right ascension of ascending node is 195 [deg]). IS-QZSS Ver. 1.4 38 0 9 J S T 2 0 1 2 M a r 2 0 1 2 A p r 9 7 5 3 1 23 21 2 0 1 1 J u n 2 0 1 1 J u l 2 0 1 1 A u g 2 0 1 1 S e p 2 0 1 1 O c t 2 0 1 2 M a y 2 0 1 1 N o v 2 0 1 1 D e c 2 0 1 2 J a n 2 0 1 2 F e b U T C 19 17 15 13 11 8 4 2 6 12 10 24 22 20 18 16 14 U T C 24 22 20 18 16 14 12 10 19 17 15 13 11 8 4 2 6 2 0 1 1 J u n 2 0 1 1 J u l 2 0 1 1 A u g 2 0 1 1 S e p 2 0 1 1 O c t 2 0 1 2 M a y 2 0 1 1 N o v 2 0 1 1 D e c 2 0 1 2 J a n 2 0 1 2 F e b J S T 2 0 1 2 M a r 2 0 1 2 A p r 9 7 5 3 1 23 21 0 9 2 0 1 1 J u n 2 0 1 1 J u l 2 0 1 1 A u g 2 0 1 1 S e p 2 0 1 1 O c t 2 0 1 2 M a y 2 0 1 1 N o v 2 0 1 1 D e c 2 0 1 2 J a n 2 0 1 2 F e b 2 0 1 2 M a r 2 0 1 2 A p r Wakkanai (Hokkaido, Japan) Tokyo J S T 2 0 1 2 M a r 2 0 1 2 A p r 9 7 5 3 1 23 21 2 0 1 1 J u n 2 0 1 1 J u l 2 0 1 1 A u g 2 0 1 1 S e p 2 0 1 1 O c t 2 0 1 2 M a y 2 0 1 1 N o v 2 0 1 1 D e c 2 0 1 2 J a n 2 0 1 2 F e b U T C 19 17 15 13 11 8 4 2 6 12 10 24 22 20 18 16 14 0 9 2 0 1 2 M a r 2 0 1 2 A p r 2 0 1 1 J u n 2 0 1 1 J u l 2 0 1 1 A u g 2 0 1 1 S e p 2 0 1 1 O c t 2 0 1 2 M a y 2 0 1 1 N o v 2 0 1 1 D e c 2 0 1 2 J a n 2 0 1 2 F e b J S T 2 0 1 2 M a r 2 0 1 2 A p r 9 7 5 3 1 23 21 2 0 1 1 J u n 2 0 1 1 J u l 2 0 1 1 A u g 2 0 1 1 S e p 2 0 1 1 O c t 2 0 1 2 M a y 2 0 1 1 N o v 2 0 1 1 D e c 2 0 1 2 J a n 2 0 1 2 F e b U T C 19 17 15 13 11 8 4 2 6 12 10 24 22 20 18 16 14 0 9 2 0 1 2 M a r 2 0 1 2 A p r 2 0 1 1 J u n 2 0 1 1 J u l 2 0 1 1 A u g 2 0 1 1 S e p 2 0 1 1 O c t 2 0 1 2 M a y 2 0 1 1 N o v 2 0 1 1 D e c 2 0 1 2 J a n 2 0 1 2 F e b Okinawa Seoul J S T 2 0 1 2 M a r 2 0 1 2 A p r 9 7 5 3 1 23 21 2 0 1 1 J u n 2 0 1 1 J u l 2 0 1 1 A u g 2 0 1 1 S e p 2 0 1 1 O c t 2 0 1 2 M a y 2 0 1 1 N o v 2 0 1 1 D e c 2 0 1 2 J a n 2 0 1 2 F e b U T C 19 17 15 13 11 8 4 2 6 12 10 24 22 20 18 16 14 0 9 2 0 1 2 M a r 2 0 1 2 A p r 2 0 1 1 J u n 2 0 1 1 J u l 2 0 1 1 A u g 2 0 1 1 S e p 2 0 1 1 O c t 2 0 1 2 M a y 2 0 1 1 N o v 2 0 1 1 D e c 2 0 1 2 J a n 2 0 1 2 F e b J S T 2 0 1 2 M a r 2 0 1 2 A p r 9 7 5 3 1 23 21 2 0 1 1 J u n 2 0 1 1 J u l 2 0 1 1 A u g 2 0 1 1 S e p 2 0 1 1 O c t 2 0 1 2 M a y 2 0 1 1 N o v 2 0 1 1 D e c 2 0 1 2 J a n 2 0 1 2 F e b U T C 19 17 15 13 11 8 4 2 6 12 10 24 22 20 18 16 14 0 9 2 0 1 2 M a r 2 0 1 2 A p r 2 0 1 1 J u n 2 0 1 1 J u l 2 0 1 1 A u g 2 0 1 1 S e p 2 0 1 1 O c t 2 0 1 2 M a y 2 0 1 1 N o v 2 0 1 1 D e c 2 0 1 2 J a n 2 0 1 2 F e b Bangkok Singapore 12 10 24 22 20 18 16 14 U T C 19 17 15 13 11 8 4 2 6 2 0 1 1 J u n 2 0 1 1 J u l 2 0 1 1 A u g 2 0 1 1 S e p 2 0 1 1 O c t 2 0 1 2 M a y 2 0 1 1 N o v 2 0 1 1 D e c 2 0 1 2 J a n 2 0 1 2 F e b J S T 2 0 1 2 M a r 2 0 1 2 A p r 9 7 5 3 1 23 21 0 9 2 0 1 1 J u n 2 0 1 1 J u l 2 0 1 1 A u g 2 0 1 1 S e p 2 0 1 1 O c t 2 0 1 2 M a y 2 0 1 1 N o v 2 0 1 1 D e c 2 0 1 2 J a n 2 0 1 2 F e b 2 0 1 2 M a r 2 0 1 2 A p r J S T 2 0 1 2 M a r 2 0 1 2 A p r 9 7 5 3 1 23 21 2 0 1 1 J u n 2 0 1 1 J u l 2 0 1 1 A u g 2 0 1 1 S e p 2 0 1 1 O c t 2 0 1 2 M a y 2 0 1 1 N o v 2 0 1 1 D e c 2 0 1 2 J a n 2 0 1 2 F e b U T C 19 17 15 13 11 8 4 2 6 12 10 24 22 20 18 16 14 0 9 2 0 1 2 M a r 2 0 1 2 A p r 2 0 1 1 J u n 2 0 1 1 J u l 2 0 1 1 A u g 2 0 1 1 S e p 2 0 1 1 O c t 2 0 1 2 M a y 2 0 1 1 N o v 2 0 1 1 D e c 2 0 1 2 J a n 2 0 1 2 F e b Sydney Perth Figure 4.2.1-1 Initial Single-satellite QZSS Visibility Time for eight Reference Locations. (See Table 3.1.1-1 for calculation condition. Dark shaded areas represent elevation angles of 60[deg] or more; light blue areas represent elevation angles of 10[deg] to 60[deg] and white is less than 10[deg]; vertical scale is hours on UTC and JST.) IS-QZSS Ver. 1.4 39 4.3 System Performance 4.3.1 Availability 4.3.1.1 QZSS Availability in the case of a Single Satellite With regard to the transmission of availability enhancement signals, QZSS availability (the percentage of the normal use signal in visibility time (10 degrees elevation angle or higher)) in the case of a single satellite shall be 95% or better. With regard to the transmission of performance enhancement signals (L1-SAIF signal), availability shall be 95% or better. As to LEX signal, specific value on the availability is not defined during the demonstration phase. 4.3.1.2 QZSS Availability in the case of a 3-satellite constellation TBD 4.3.2 Alert flag, URA and Health Data 4.3.2.1 Notification of Alert flag, URA and Health Data Data relating to the status of the QZS signals and other GNSS systems’ signals are sent to the user by means of the "Alert" flag, URA and health data. “Alert” flag will set to “1” in the case that SIS accuracy exceeds 9.65 [m] or other troubles for QZS happens (Default case: “Alert“ flag=”0”). 4.3.2.2 Maximum Notification Times The maximum notification times relating to URA, the "Alert" flag, and health data are defined as the worst case (longest) time required from the moment of detecting anomaly by a QZSS Monitor Station until the total notification message arrives at the user's antenna input terminal. Figure 4.3.2-1 shows the maximum notification times for “Alert” flag, URA, Health data and integrity data. 4.3.2.3 False Alarm Probability The probability that the "Alert" flag will be erroneously set to "1" (even though the corresponding QZS signal is normal and can be used) shall be 1x10 -6 or less. 4.3.2.4 Mis-Detection Probability The probability that the "Alert" flag will erroneously not be set to "1" (even though an error has occurred with respect to the QZS signal and the signal should not be used) shall be 1x10 -3 or less. IS-QZSS Ver. 1.4 40 Integrity data notification time L1C 0 (Event Occurrence) time 50 100 150 200 250 300 Alert URA Health (Subframe 1) Health (Subframe 4,5) ※ 30s 60s 90s 900s L1C/A Alert (L1CHealth) URA Health ※ 90s Alert URA Health (MSG Type 10) Health (MSG Type 53) ※ L2C 40s 70s 90s 240s Alert URA Health (MSG Type 10) Health (MSG Type 53) ※ L5 60s 90s 240s UDREI 24s L1-SAIF LEX Alert URA Health 90s 240s 30s 24s 24s 400s ※Target is the health information of Other GNSS systems Figure 4.3.2-1 “Alert” flag, URA, Health Data and Integrity Data Maximum Notification Time 4.3.2.5 L1-SAIF Signal Specifications The appropriate protection level shall be computed within 30 seconds by user receivers at any location in the service area even when an error condition occurs. The probability of the user positioning error exceeding the protection level shall be 0.00001/hour or less. 4.3.3 Accuracy 4.3.3.1 SIS Accuracy provided by QZSS Availability Enhancement Signals The SIS accuracy provided by all QZS signals (except the L1-SAIF and LEX signals) shall be such that the URA will not exceed 2.60 [m] with a probability of 95% or better including the error of the time systems’ offset and the coordinate systems’ offset between QZSS and GPS. 4.3.3.2 Accuracy of Interoperability with Existing GNSS 4.3.3.2.1 Time System Offset The QZSS time scale offset from GPS time shall not exceed 2.0 [m] (about 6.67 [ns]) with a probability of 95% or better. The QZSS time scale offset from Galileo shall not exceed TBD [m] (TBD [ns]) with a probability of 95% or better. 4.3.3.2.2 Coordinate System Offset The QZSS coordinate system offset from GPS and Galileo shall be 0.02 [m] or less IS-QZSS Ver. 1.4 41 4.3.3.3 Accuracy of Ionospheric Parameters The accuracy available from the ionospheric parameters transmitted by the QZS shall be such that user receivers in the regions indicated in Section 4.1.5 will be able to correct the associated range measurements to within 14.0 [m] or better, with the exception of intervals during large ionospheric disturbances. A “large ionospheric disturbance” occurs when the ionospheric delay exceed TBD[m] (about 5% in a year). 4.3.3.4 Positioning Accuracy by means of Availability Enhancement Signals The horizontal positioning accuracy shown in Table 4.3.3-1 shall be provided 95% of the time or more, through QZS signals (except L1-SAIF and LEX signals) used in combination with GPS signals, assuming all signals arrive at 10 degrees elevation angle or higher. Table 4.3.3-1 Positioning Accuracy by means of Availability Enhancement Signals Horizontal Positioning accuracy Notes Equivalent to modernized GPS signal (horizontal positioning accuracy 95%) Single frequency: 21.9 m Dual frequency: 7.5 m Single frequency (user ranging error: 7.3 m) Dual frequency (user ranging error: 2.5 m) 4.3.3.5 Positioning Accuracy by means of Performance Enhancement Signals The positioning accuracy shown in Table 4.3.3-2 shall be achievable with the QZSS L1-SAIF signal, except in cases of large multipath error or a large ionospheric disturbance. Table 4.3.3-2 Positioning Accuracy by means of Performance Enhancement Signals Positioning accuracy Notes Submeter class: 1 m (rms) (wide-area DGPS performance enhancement) L1-SAIF signal use more than 5 degree elevation angle IS-QZSS Ver. 1.4 42 5 QZSS Signal Properties QZSS provides six types of signals to users. Section 5.1 describes the fundamental properties of all QZS signals. Subsequent sections provide details such as the signal configuration, carrier wave properties, code properties and navigation message configuration and content for each of the six signals transmitted by QZS satellites. 5.1 QZS Power Levels, Bandwidths and Center Frequencies All QZS signals are right-hand circularly polarized spread spectrum signals. Table 5.1-1 shows the center frequencies, bandwidths and received minimum power levels of these signals. After being superimposed with a navigation message, the baseband QZS signals are modulated with a spread spectrum pseudorandom noise (PRN) code and then up-converted by an RF carrier at the indicated center frequency. Table 5.1-1 QZS signal specifications Signal name I/Q channel identification Center frequency Frequency Bandwidth Received Minimum Power Level* L1C/A L1 CA 1575.42 MHz 24.0 MHz （±12.0 MHz） -158.5 dBW L1C L1 CD 24.0 MHz （±12.0 MHz） -163.0 dBW -157.0 dBW (Total) L1 CP -158.25 dBW L1-SAIF - 24.0 MHz （±12.0 MHz） -161.0 dBW L2C - 1227.60 MHz 24.0 MHz （±12.0 MHz） -160.0 dBW (total) L5 L5 I 1176.45 MHz 24.9 MHz （±12.45 MHz） -157.9 dBW -154.9 dBW (Total) L5 Q 24.9 MHz （±12.45 MHz） -157.9 dBW LEX - 1278.75 MHz 39.0 MHz （±19.5 MHz） -155.7 dBW (total) *: this is defined in Section 5.1.1.8. IS-QZSS Ver. 1.4 43 5.1.1 Overview of signal properties 5.1.1.1 QZS Signal configuration Table 5.1.1-1 shows a summary of the ranging code, modulation method and navigation message structure for each of the QZS signals. Table 5.1.1-1 Configuration of QZS signals Signal name (abbreviation) Channel identification Ranging code and modulation method Navigational message L 1 s i g n a l s L1C/A signal (QZS-L1) - One of the PRN codes for the GPS C/A signal in Applicable Document (1). Modulation method is BPSK (1). Same data structure, bit rate and coding method as the C/A signal in Applicable Documentation (1) in Chapter 2; same type of navigation message. L1C signal (QZS-L1C) L1C D One of the PRN codes for the GPS PRN code specified in Applicable Document (3). Modulation method of QZS-1 is BOC (1, 1). Modulation method of LIC signals after “Phase Two” should be studied further if MBOC could be adopted. Same data structure, bit rate and coding method as in Applicable Documentation (3) in Chapter 2; same type of navigation message. L1C P Modulated using the same code sequence as the overlay code in Applicable Documentation (3) in Chapter 2. L1-SAIF signal (QZS-L1-SAIF) - One of the PRN codes for the GPS C/A signal in Applicable Document (1). Modulation method is BPSK (1). Same data structure, bit rate and coding method as in Applicable Documentation (4) in Chapter 2; same type of navigation message. L2C signal (QZS-L2C) - One of the PRN codes for the GPS L2C signal in Applicable Document (1). Modulation method is BPSK (1). L2C (C M ) code Same type of Navigation message with the same data structure, bit rate and coding method as in Applicable Document (1). L2C (C L ) code Dataless (i.e., no data is modulated onto this signal) L5 signal （QZS-L5） I channel One of the PRN codes for the GPS L5 signal in Applicable Document (2). Modulation method is BPSK (10). Same type of Navigation message with the same data structure, bit rate and coding method as in Applicable Document (2). Q channel One of the PRN codes for the GPS L5 signal in Applicable Document (2). Modulation method is BPSK (10). Dataless LEX signal （QZS-LEX） - Small Kasami sequence. Modulation method is BPSK (5). 2 channels are obtained by chip by chip time multiplexing. Short code 2000 bits/frame At the beginning of the frame, in addition to the preamble there is a type ID that identifies the content of the frame. 250 sps x 8 = 2 kbps by means of code-shift keying. A Reed-Solomon code is added. Long code Dataless IS-QZSS Ver. 1.4 44 5.1.1.1.1 Signal configuration of L1 signals QZS transmits three signals using the L1 center frequency: the L1C/A signal, the L1C signal and the L1-SAIF signal. The L1 availability enhancement signals include two carrier waves (L1C/A、L1 CD and L1 CP ) that are designed to maintain a specified phase relationship. The I-channel contains L1C/A and L1 CD while the orthogonal Q-channel contains L1 CP . The phase relationship specifications are given in Section 5.1.1.6.1. L1C/A, L1 CD and L1 CP are BPSK modulated with bit strings equivalent to the L1C/A signal, the L1C signal data channel, and the L1C signal pilot channel, respectively. When the L1 CD modulation bit of QZS-1 is 0, the phase of the L1 CD carrier wave is 0°. The L1 CD carrier wave is 180° reversed when the L1 CD modulation bit is 1. When the L1 CP modulation bit is 1, the phase of the L1 CP carrier wave is 90° advanced. When the L1 CP modulation bit is 0, the phase of the L1 CP carrier wave is 90° delayed. The phase relation of LI signal for QZS-1 is not same as GPS (Brock III) (Refer to Applicable Documents (3). L1 CD and L1 CP for QZS-1 are orthogonal each other at right angles, but L1 CD and L1 CP for GPS are in phase (Figure 5.1.1-1). The phase relation of LI signal for a satellite after “Phase Two” is under study. L1 CD 、L1 C/A L1 CP QZS-1 L1 CD 、L1 CP L1 C/A GPS Figure 5.1.1-1 Phase Relations of LI Signal for QZS-1 and GPS 5.1.1.1.2 L2C signal configuration The L2C signal has a single carrier wave. This carrier wave is BPSK modulated using a certain bit string L2C C . This bit string is generated by two types of bit strings CM L C 2 , CL L C 2 (corresponding to two channels) that are selected alternately in a time-multiplexed manner. 5.1.1.1.3 L5 signal configuration The L5 signal has two carrier waves that are orthogonal with respect to one another. The phase relationship specifications are given in Section 5.1.1.6.1. Each of these carrier waves is BPSK modulated by two types of bit strings L5I5 C , L5Q5 C (corresponding to the two channels). When the L5 I modulation bit is 0, the phase of the L5 I carrier wave is 0°. The L5 I carrier wave is 180° reversed when the L5 I modulation bit is 1. When the L5 Q modulation bit is 1, the phase of the L5 Q carrier wave is 90° advanced. When the L5 Q modulation bit is 0, the phase of the L5 Q carrier wave is 90° delayed. IS-QZSS Ver. 1.4 45 5.1.1.1.4 L1-SAIF signal configuration The L1-SAIF signal has a single carrier wave. This carrier wave is BPSK modulated by a certain bit string L1SAIF C . 5.1.1.1.5 LEX signal configuration The LEX signal has a single carrier wave. This carrier wave is BPSK modulated by a certain bit string LEX C . This bit string is generated by two types of bit strings LEXS C , LEXL C (corresponding to two channels) that are selected alternately in a time-multiplexed manner. 5.1.1.2 QZS Operational Frequency The operational QZS frequency, f s , is offset with respect to the reference frequency of f 0 = 10.23 MHz, in order to provide compensation for the relativistic effect to which the QZS satellites are subjected due to their orbital motion. The frequency is as follows: ( ) Hz Hz f f f f s 994476823 . 10229999 10230000 10 399 . 5 1 1 10 0 0 ~ × × ÷ = × | | . | \ | A + = ÷ Since the QZS orbits are elliptical, the impact of the relativistic effect will slowly fluctuate. However, the equations in Section 6.3.2 (2) can be used to compensate for this. In addition, the equations in Section 6.3.2 (1) with the SV clock parameters (a f0 , a f1 , a f2, ) included in the QZSS navigation messages can be used to compensate for the fluctuation of QZSST depended on other sources. 5.1.1.3 Correlation loss Correlation loss is defined as the difference between the SV power received in the specified signal bandwidth (e.g., ± 12 MHz for the L1 carrier) and the signal power recovered in an ideal receiver of the same bandwidth, which perfectly correlates using an exact replica of the waveform within an ideal (sharp cut-off) bandpass filter with linear phase. For all QZSS signals, the correlation loss that occurs in the navigation payload of the QZS satellite shall not exceed 0.6 dB. 5.1.1.4 Carrier phase noise For all QZSS signals, the spectral density of the phase noise for the unmodulated carrier wave (i.e., prior to modulation with the PRN code and navigation message) shall be such that a phase-locked loop (PLL) with single-sided bandwidth of 10 Hz will be able to track the carrier phase to an accuracy of 0.1 radians (RMS). Figure 5.1.1-2 shows the phase noise requirements for all QZSS signals in more detail. -47 -47 -77 -94 -101 -105 -110 -120 -100 -80 -60 -40 -20 0 1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 Offset Frequency (Hz) P h a s e N o i s e D e n s i t y ( d B c / H z ) Figure 5.1.1-2 Phase Noise of all QZS signals IS-QZSS Ver. 1.4 46 5.1.1.5 Spurious characteristics For all QZSS signals, in-band spurious transmissions shall be at least 40 dB below the power level of the unmodulated carrier wave (i.e., prior to superposition of the PRN code and navigation message). 5.1.1.6 Phase relationships among QZS signals 5.1.1.6.1 Phase orthogonal The two carrier waves (L1 CD and L1 CP , L5 I and L5 Q ) are maintained in a 90° orthogonal phase relationship with one another. The variation in this phase relationship shall not exceed ± 5.0°. 5.1.1.6.2 Phase relationship of PRN code and carrier wave The fluctuations in the difference between the Pseudo Random Noise (PRN) code phase and the carrier wave phase at the antenna phase center for all QZS signals shall not exceed 1.2 ns. Additionally, within any 30 s period, fluctuations in the difference between the PRN code phase and the carrier wave phase shall not exceed 0.01 ns (equivalent to 0.3 cm ranging error). 5.1.1.6.3 PRN code jitter 5.1.1.6.3.1 PRN code jitter The jitter, σ jitter , of the PRN code zero-crossing interval (according to Figure 5.1.1-3) shall not exceed 2.0 ns for a value of 3σ. Complete, ideal PRN code Realistic PRN code with edge jitter σ jitter σ jitter σ jitter σ jitter σ jitter σ jitter σ jitter Figure 5.1.1-3 Definition of code jitter σ jitter 5.1.1.6.3.2 Delay in PRN code rising/falling edge For the PRN code, the mean value for the rising edge delay time (or advance time), Δ, (as illustrated in Figure 5.1.1-4) when the falling edge is viewed to be correct shall not exceed 1.0 ns. IS-QZSS Ver. 1.4 47 Complete PRN code PRN code with late falling edge PRN code with late rising edge Δ Δ Δ Δ Δ Δ Δ Figure 5.1.1-4 Definition of delay time, Δ, for PRN code rising/falling edge IS-QZSS Ver. 1.4 48 5.1.1.7 PRN code phase relationships among signals All QZS signals are generated from the same single clock with the operational frequency indicated in Section 5.1.1.2. The PRN code phase differences between QZS signals at the antenna phase center shall not exceed the values shown in Table 5.1.1-2. Table 5.1.1-2 Differences in Pseudo Random Noise (PRN) code phases among QZS signals L2 LEX L5 25 ns 35 ns 20 ns L1 15 ns 10 ns L2 20 ns LEX The fluctuations in phase difference shall not exceed 2 ns for a value of 3σ. Within any 30 s period, QZS phase differences shall not exceed 0.01 ns ( ~0.3 cm). These phase differences are included in navigation messages (T GD , ISC (Inter-Signal Correction), etc.) and transmitted to users. The accuracy is 4.5 ns (3-sigma) for T GD , and 3.0 ns (3-sigma) for ISC. 5.1.1.8 Minimum received power level A ground-based isotropic antenna with a gain of 0 dBi for circularly polarized wave reception is provided and, when QZS signals are received from a Quasi Zenith Satellite (QZS) with an elevation angle of 10° or more, the reception power must not be lower than the value indicated in Table 5.1-1. In general, the reception power in each part of the service area is as shown in Section 3.1.3.6. 5.1.1.9 Polarization characteristics All QZS signals are right-hand circularly polarized. The axial ratio (power ratio of the long axis to short axis) of the QZS circularly polarized waves, in the beam range of ± 10° from the boresight direction, shall not exceed 1.0 dB for the L1 signals and 2.0 dB for the L2, LEX and L5 signals. The axial ratio of the L1-SAIF signal is less than 1.0 dB. 5.1.1.10 Antenna Phase Center Characteristics For all QZS signals with the exception of the L1-SAIF signal, the antenna phase center of the L-ANT is in the range of ± 1 cm in the beam range of ±10 deg from the direction of the L-ANT boresight. The L1-SAIF signal is transmitted from another antenna, LS-ANT. And the antenna phase center of the LS-ANT is in the range of +/- 1 cm from the direction of the boresight. Because the L1-SAIF signal is transmitted from the other antenna, the ephemeris data of L1-SAIF signal is not same as the ephemeris of the other signals, such as L1 C/A signal, L1C signal, L2C signal and L5 signal. IS-QZSS Ver. 1.4 49 5.1.1.11 PRN Code Numbers 5.1.1.11.1 Availability Enhancement Signals QZSS uses the same type of PRN code as GPS. Detailed information are referenced in the sections starting with 5.2 and in Applicable Documents (1), (2) and (3). The PRN code numbers used by QZSS are 193-197. The initial QZS is assigned code number 193, and the second and succeeding QZS are assigned numbers in sequence starting with 194. PRN code numbers 198-202 are used for QZS maintenance/test purposes and must not be used by users. 5.1.1.11.2 Performance Enhancement Signals (1) L1-SAIF signal A PRN code of the same type as the GPS L1C/A signal is used. For more information 3 are referenced in the Applicable Documents (1). The PRN code numbers are 183-187. The initial QZS is assigned code number 183, and the second and succeeding QZS are assigned numbers in sequence starting with 184. PRN code numbers 188-192 are used for QZS maintenance/test purposes and must not be used by users. (2) LEX Signal A small Kasami series is used. For more information, see Section 5.7. The numbers are 193-197. The initial QZS is assigned number 193, and the second and succeeding QZS are assigned numbers in sequence starting with 194. Numbers 198-202 are used for QZS maintenance/test purposes and must not be used by users. 3 The allowance of PRN Code is approved by GPSW through the process defined by “PSEUDO RANDOM (PRN) CODE ASSIGNMENT PROCESS”(GLOBAL POSTIONING SYSTEMS WING (GPSW), 1 February 2007). (The allowance of LIC signal will be approved officially after the IS-GPS-800 is established and the revision of above document is completed. The allowance of LIC for QZSS has been agreed at the GPS-QZSS TWG.) IS-QZSS Ver. 1.4 50 5.1.2 Navigational messages 5.1.2.1 Content of Navigation Messages QZSS superimposes onto the PRN code data to aid identification of QZS position as well as other data described in the following subsections. As is typical of other GNSS systems, QZS transmits this information in the form of navigation messages. The content of the major QZSS navigation messages is shown below. For detailed information regarding the navigation messages broadcast on each QZSS signal, see the sections beginning with 5.2. 5.1.2.1.1 Ephemeris Data and SV Clock Parameters QZSS provides users with Ephemeris data and SV clock parameters referenced to the QZS antenna phase center. These are available for positioning calculations on the part of users. 5.1.2.1.2 Almanac Data QZSS provides Almanac data referenced to the QZS antenna phase center. These data are available for satellite selection calculations and Doppler calculations by users. 5.1.2.1.3 URA, Health Data QZSS provides users with the URA and Health data (in case of L1C/A) shown in Figure 5.1.2-1. Almanac Health Ephemeris Health RF Signal Strength Status Navigation Message Status S u m m a r y ＋ O t h e r m a l f u n c t i o n 5 bits 3 bits 5 bits 1 bit URA Index 4 bits Accuracy Subframe 4,5 Subframe 1 5 bits health 3 bits health 1 bit health Satellite Health 5 bits 1 bit 1 bit health Summary ＋Other malfunction Figure 5.1.2-1 QZS URA and Health Data on L1C/A signal 5.1.2.1.3.1 "Alert" Flag The "Alert" flag is transmitted by all subframes of the L1C/A signal, by all message types of the L2C and L5 signals, and by bit 33 of subframe 2 of the L1C signal (the section named "L1C Signal Health" in Applicable Document (3)). When the ALERT flag is set to "1," this indicates that the SIS accuracy of the corresponding QZS signal is worse than 9.65 [m], or that an error of some kind has occurred on the QZS such that the specified accuracy cannot be guaranteed. Note that 9.65 [m] corresponds to the upper limit for the NMCT correction indicated in Section 5.2.2.2.5.2 (8). The operating concept for the ALERT flag is discussed in Section 3.1.2.1.3. IS-QZSS Ver. 1.4 51 QZSS constantly monitors the SIS error of the QZS signal and the status of the QZS and transmits the data to the user within the seconds, which is specified in Section 4.3.2.2 after an error has occurred. In such cases, use of the corresponding signal is not advised, however, users may do so at their own risk. 5.1.2.1.3.2 URA, URA oe , URA oc URA index are transmitted by subframe 1 of the L1C/A signal, URA oe index are transmitted by message type 10 of the L2C and L5 signals, and subframe 2 of the L1C signal, and URA oc index are transmitted by message type 30, 31, 32, 33, 34, 35, 37, 46, 49, 51 and 53 of the L2C and L5 signals and subframe 2 of the L1C signal. These are related to the SIS error of the corresponding signal. Regardless of whether the "Alert" flag is set to "0" or "1", QZSS ensures that the current SIS error of the corresponding signal does not exceed the value expressed by URA, URA oe and URA oc . The probability that instantaneous URE (User Range Error) becomes greater than 5.73 × URA is less than 1 × 10 -8 /h. The algorithm used to determine the value of URA, URA oe and URA oc from URA index, URA oe index and URA oc index is the same as that in Applicable Documents (1), (2) and (3). QZSS constantly monitors the SIS error of all QZS signals and generates the URA parameters based on the data received at Monitor Stations for the past 30 seconds. The URA parameters are transmitted for use as reference data. When the URA parameters indicate poor accuracy, use of the corresponding signal is not advised, however, users may do so at their own risk. 5.1.2.1.3.3 5-bit Health The 5-bit health word is transmitted by the last 5 bits of the Ephemeris health [Section 5.2.2.2.3(4)] included in subframe 1 of the L1C/A signal, and the last 5 bits of the Almanac health [Section 5.2.2.2.5.2(2)(b)] and satellite health [Section 5.2.2.2.5.2(3)] included in subframes 4 and 5. The data included in the 5-bit health relate to the signal health of the satellite, such as L1 C/A signal, L2C signal, L5 signal, L1C signal and LEX signal. Each bit is set to "0" when the signal at the satellite is broadcasted correctly and available, and is set to ”1” when the health of each signal is bad. The definition of the bit allocation is shown in the Table 5.1.2-1. For GPS satellites, if the signal is not broadcasted or the status of the signal is unhealthy (judged by MCS), the 1 bit health of the signal is set to "1". In the case of the 1bit health="1", the signal of the satellite should be used at the user’s own risk. Table 5.1.2-1 Details of Health (5-bit health) code for all QZSS signals Bit Allocation QZS Health GPS Health Notes Bit 1 （MSB） Health of L1C/A signal Health of L1C/A signal Bit 2 Health of L2C signal Health of L2C signal Bit 3 Health of L5 signal Health of L5 signal Bit 4 Health of L1C signal Health of L1C signal Bit 5 （LSB） Health of LEX signal reserved Set “1” when GPS IS-QZSS Ver. 1.4 52 5.1.2.1.3.4 3-bit health and 1-bit health The 3-bit health word is transmitted by the first 3 bits of the Almanac Health [5.2.2.2.5.2(2)(b)] included in subframe 4 and 5 of the L1C/A signal. The 1-bit health word is transmitted by the first bit of the Ephemeris Health [5.2.2.2.3(4)] included in subframe 1 of the L1C/A signal, by the first bit of the Satellite Health [5.2.2.2.5.2(3)] included in subframe 4 and 5, by "L1 Health", "L2 Health" and "L5 Health" in message type 10, 12, 31 and 37 in the L2C and L5 signals, and by "L1 Health", "L2 Health" and "L5 Health" on pages 3 and 4 in subframe 3 of the L1C signal. These Health bits indicate the status of the Navigation Message for the QZS signal transmitted by the associated satellite. The definition of the 3-bit Health word is the same as in Section 20.3.3.5.1.3 in Applicable Document (1). The 1-bit Health is set to "1" in the event that there is an error with any one or more of the following: the Navigation Message, power level, modulation, etc. QZSS constantly monitors the status of not only the QZS but also other satellite positioning systems including GPS. The MCS judges whether the system is in normal or error status and then generates these bits accordingly and provides the data to the user within the seconds, which is specified in Section 4.3.2.2. For all codes other than that corresponding to “All Signals OK”, users are cautioned to only use the associated signal at their own risk. 5.1.2.2 Timing of subframes, pages and data sets 5.1.2.2.1 IODE, IODC The IODE in the same data set has the same 8 bits as the 8 LSBs of the 10-bit IODC. (In other words, if the last 8 bits of IODE and IODC are the same, these constitute the same data set.) In addition, unlike GPS’s IODC, 2bits (MSB) of IODC in QZSS signals are used as counter for SV clock parameter and count up once every 15 minutes. For transmissions of IODE and IODC for different data sets, the following rules apply: (1) The transmitted IODC is different from the value transmitted from the satellite for the previous seven days. (2) The transmitted IODE is different from the value transmitted from the satellite for the previous six hours. (3) When updating only the SV Clock parameter without updating the Ephemeris data, only the first two bits of the IODC are updated. In such cases, the epoch of the SV Clock parameter is not updated. It is the same as the epoch of the Ephemeris data. 5.1.2.2.2 Relationship between epoch data and data set update The epoch for Ephemeris data that possesses a new data set is assured to be different from that transmitted prior to updating. 5.1.2.2.3 Data set update With the exception of the first data set after service is resumed following orbit maintenance and attitude maintenance (as described in Section 3.1.2.2.1.1 and 3.1.2.2.1.2, respectively), the data set is updated at the boundary of whole number hours. The initial data set may be updated to a new data set at any time, even during the effective period for that data set. The beginning of the transmission interval for each data set is the same: the beginning of the curve fit interval for the data set. The data set is valid for the duration of the curve fit interval. IS-QZSS Ver. 1.4 53 In the process of updating the shortest data set, the data sets in subframes 1, 2 and 3 in the L1C/A signal, in message type 10 and 11 in L2C and L5 signals, and in subframe 2 in the L1C signal are updated once per hour. The corresponding curve fit interval is 2 hours. 5.1.2.2.4 Data set update at the end-of-week crossover At the end-of-week crossover, the L1C/A signal transmission starts again from subframe 1. In addition, the subframe 4 and 5 cycles that are dependent on the data set start again at the end-of-week crossover, regardless of what pages were transmitted prior to the end-of-week crossover. The L2C and L5 signals start again from message type 10 at the end-of-week crossover. The cycles for message types that are dependent on the data set start again at the end-of-week crossover, regardless of what message types were transmitted prior to the crossover. With the L1C signal, at the end of week crossover, the cycles for message types that are dependent on the data set start again at the end of week crossover, regardless of what message types were transmitted prior to the crossover. IS-QZSS Ver. 1.4 54 5.2 L1C/A signal 5.2.1 RF characteristics 5.2.1.1 Signal configuration In accordance with Section 5.1. 5.2.1.2 Carrier wave properties In accordance with Section 5.1. 5.2.1.3 Code properties 5.2.1.3.1 Code attributes Same as in Sections 3.2.1.3 and 3.3.2.3 of Applicable Document (1). However, the PRN code is as described in Section 5.1.1.11.1 of this document. 5.2.1.3.2 Non-Standard Code (NSC) In the event that a problem with the satellite or the ground-based system occurs, a non-standard code (NSC) is transmitted. This is done to protect users by ensuring that they do not receive or use erroneous navigation data. 5.2.2 Messages 5.2.2.1 Message configuration Each word is made up of 30 bits. Ten words make up one subframe. Five subframes make up one loop. This message configuration is the same as in Applicable Document (1). 5.2.2.1.1 Preamble The 8-bit preamble added to the beginning of the 10 words of the subframe is the same as in Section 20.3.3.1 of Applicable Document (1). 5.2.2.1.2 Parity algorithm The 6-bit parity bits are added to the end of the 30-bit word is the same (32, 26) Hamming Code as specified in Section 20.3.5.1 of Applicable Document (1). 5.2.2.1.3 Parity Check algorithm See section 20.3.5.2 of Applicable Document (1). 5.2.2.2 Message content 5.2.2.2.1 Telemetry word (1st word) This word is used for QZSS maintenance/test purposes. 5.2.2.2.2 Handover word (HOW) (2nd word) With the exception of the following, same as 20.3.3.2 in Applicable Document (1). For information on the use of the "Alert" flag in bit 18, see Section 3.1.2.1.3. For information on the content of the "Alert" flag, see Section 5.1.2.1.3. The Anti-Spoof flag (A-S), bit 19, is "0" indicating that the QZSS is in non-A-S mode. IS-QZSS Ver. 1.4 55 5.2.2.2.3 Subframe 1 Subframe 1 includes the clock data, etc. for the corresponding satellite. For more information regarding the general content of subframe 1, see Section 20.3.3.3.1 in Applicable Document (1). The parameter characteristics of Subframe 1 (number of bits, LSB scale factor, range, unit, data structure (page format etc.) etc.) are the same as in Section 20.3.3.3.2 in Applicable Document (1). (1) Transmission Week Number Same as 20.3.3.3.1.1 in Applicable Document (1). (2) L2 channel code Bits 11 and 12 (L2 channel code) in word 3 are fixed at "10." (3) Satellite User Ranging Accuracy Index: URA Index Bits 13-16 in word 3 constitute the URA index. The algorithm signified by this URA index that is used to determine the specific user positioning accuracy for the satellite is the same as in Section 20.3.3.3.1.3 in Applicable Document (1). For more information about how to use the URA index, see Section 3.1.2.1.3. For more information about the content of URA, see Section 5.1.2.1.3. (4) Health Data for the Satellite (Ephemeris Health) Bits 17-22 in word 3 constitute the health of the corresponding QZS. For more information on how to use the Ephemeris health, see Section 3.1.2.1.3. Health data (Almanac Health and Satellite Health) are also present in Subframe 4 & 5, but the refresh cycle for the Health data in Subframe 1 is more rapid, so the data are not identical. (a) Summary of Navigation Message status for signals transmitted by the corresponding QZS (1-bit health) Bit 17 in word 3 shows a summary of the navigation message. The definition is in accordance with Section 20.3.3.3.1.4 in Applicable Document (1). (b) Status of signals transmitted by the corresponding QZS (5-bit Health) Bits 18-22 in word 3 indicate the status of the signals transmitted by the corresponding QZS. The definition is in accordance with Table 5.1.2-1. (5) Issue of Data, Clock (IODC) Bits 23 and 24 in word 3 indicate the 2 MSBs of the 10-bit IODC. Bits 1 - 8 in word 8 indicate the 8 bits beginning with LSB in the IODC. IODC shows issuance number of data set. Users can detect the update of data set by the time series behavior of IODC. IODC is changed each time the SV Clock parameters (a f0 , a f1 , a f2 etc.) are updated. The shortest update period is every 900 seconds. For more information regarding IODC changes, etc., see Section 5.1.2.2. (6) Data flag for L2P code As there is no L2P code, bit 1 in word 4 is fixed at "1." IS-QZSS Ver. 1.4 56 (7) Internal signal group delay error parameter Bits 17-24 in word 7 indicate the internal signal group delay error parameter GD T for users who use only the L1C/A or only the L2C signal. For the definition and user algorithm, see Section 6.3.3 and 6.3.4. Bit string "10000000" indicates that the group delay value cannot be used. (8) SV Clock parameters For information regarding the SV Clock parameters (t oc , a f2 , a f1 , a f0 ) needed for users to correct the SV clock offset, see Section 20.3.3.3.1.8 in Applicable Document (1). The user algorithm is described in Section 6.3.2. 5.2.2.2.4 Subframe 2 & 3 Subframe 2 and 3 contain the Ephemeris data, etc., for the corresponding satellite. For more information on the general content, see Section 20.3.3.4.1 in Applicable Document (1). The parameter characteristics of Subframe 2 and 3 (number of bits, LSB scale factor, range, unit, sub-commutation, etc.) are the same as in Section 20.3.3.4.2 in Applicable Document (1). (1) AODO = NMCT (Navigation Message Correction Table) effective time Bits 288 - 292 of subframe 2 constitute the effective time for the NMCT (navigation message correction table). The parameter characteristics of Subframe 2 and 3 (number of bits, LSB scale factor, range, unit, data structure (page format etc.), etc.) is the same as in Section 20.3.3.4.2 of Applicable Document (1). The certain part of the user algorithm is not same as in Section 20.3.3.4.4 of Applicable Document (1). When AODO is a binary value of “11111”, NMCT cannot be used. This is also the same as in Section 20.3.3.4.4 of Applicable Document (1). The NMCT is transmitted from different QZS at different timings. Among these NMCT, the most recent NMCT is the one with the largest t nmct value calculated using following equations.. AODO t t oe nmct ÷ = Note: nmct t must account for the beginning or end of week crossover in following equations. 800 , 604 t t then 400 , 302 t t if 800 , 604 t t then 400 , 302 t t if nmct nmct nmct nmct nmct nmct ÷ = ÷ < ÷ + = > ÷ - - oe t : Reference time Ephemeris (seconds into week) of the AODO broadcasting satellite [s] - t : User receiver time (in GPST) If calculated nmct t is larger than User receiver time - t , NMCT is available, and otherwise, NMCT is not available. In addition, to respond the crossovers by ephemeris updates, if the difference between oe t and - t is less than 300 [s], ERD should not be used. IS-QZSS Ver. 1.4 57 ( ) ( ) | | valid NOT , else VALID are ERDs , else valid NOT , s 300 t t if , 0 t t if et arg t oe nmct < ÷ > ÷ - - et arg t oe t : Reference time ephemeris for the target satellite to correct (2) Issue of Data, Ephemeris (IODE) Bits 61 - 68 of subframe 2 and bits 271 - 278 of subframe 3 constitute the IODE. The meaning of IODE is the same as in Section 20.3.4.4 of Applicable Document (1). IODE changes each time the Ephemeris data (a, e, i and the other 6 orbital elements and C IC , C IS and other correction parameters) are updated. The shortest update period is 1 hour. For more information on the use of IODE changes, etc., see Section 5.1.2.2. (3) Ephemeris data The Ephemeris data defined in Section 20.3.3.4.1 of Applicable Document (1) are transmitted by subframe 2 and 3. The user algorithm described in Section 6.3.5. (4) Fit interval flag: Effective time flag for Ephemeris data Bit 17 in word 10 of subframe 2 is the fit interval flag. When the curve fit interval is set to “0”, the Ephemeris data are effective for 2 hours. When the curve fit interval is “1”, the Ephemeris data are effective for more than 2 hours. IS-QZSS Ver. 1.4 58 5.2.2.2.5 Subframe 4 & 5 Subframes 4 and 5 include the Almanac data, Almanac Reference Week Number, Coordinated Universal Time (UTC) parameter, Ionosphere parameter, NMCT, etc. The parameter characteristics of subframes 4 and 5 (number of bits, LSB scale factor, range, unit, data structure (page format etc.) etc.) are the same as in Section 20.3.3.5.1 of Applicable Document (1). Unlike GPS legacy navigation message in Applicable Document (1), 25 pages for QZSS do not necessarily constitute one data set. The content of the transmitted data can be identified using the SV ID and the data ID. For instance, the data set can be extended to 30 pages or more to send several GNSS system parameters by using this flexible page concept. 5.2.2.2.5.1 Subframe 4 & 5 content identification (1) Data identification The content of Subframes 4 and 5 can be distinguished by means of the data ID in bits 61 - 62 and the Space Vehicle (SV) ID in bits 63 - 68. The data ID identifies the type of satellite positioning system (for example, GPS, QZSS, etc.). The SV ID identifies the Space Vehicle Number of the satellite and other information (for example, whether the data constitute an ionospheric parameter, NMCT, etc.). The method used for identification is shown in Table 5.2.2-1. IS-QZSS Ver. 1.4 59 Table 5.2.2-1 Content identification using Data ID and Space Vehicle ID SV ID Data ID = 00 (b) (GPS) Data ID=01(b)、10(b) (Spare) Data ID=11(b) (QZSS) 00(d) Dummy satellite Dummy satellite 01～32(d) GPS satellite Almanac QZS almanac 33～48(d) Spare 49(d) GPS satellite Almanac Reference Week Number, Almanac reference time and Satellite Health data of GPS satellite (PRN=1-24) 50(d) GPS satellite Almanac Reference Week Number, Almanac reference time and Satellite Health data of GPS satellite (PRN=25-32) 51(d) GPS satellite Almanac Reference Week Number, Almanac reference time and Satellite Health data of GPS satellite (PRN=1-24) QZS Almanac Reference Week Number, Almanac reference time and Satellite Health data of QZS (PRN=193-197) 52(d) Navigation Message Correction Table (NMCT) for GPS satellite (PRN=1-30) 53(d) Navigation Message Correction Table (NMCT) for QZS (PRN=193-197) and GPS satellite (PRN=31,32) 54(d) Navigation Message Correction Table (NMCT) for Spare satellite 55(d) Special message 56(d) GPS ionospheric parameters and relationship between UTC (USNO) and GPST Ionospheric parameters especially for Japan and relationship between UTC (NICT) and GPST 57(d) 58(d) 59(d) 60(d) 61(d) 62(d) 63(d) A-S flag and Satellite Configuration of GPS (PRN=1-32) and Satellite Health data of GPS satellite (PRN=25-32) Spare Spare Spare Spare Spare (2) Data repeat transmission period Data repeat transmission period is depended upon Navigation pattern table (See Section 7.2.4.3) IS-QZSS Ver. 1.4 60 5.2.2.2.5.2 Content of subframes 4 & 5 (1) Dummy data When the SV ID is 0, the content comprises alternating values of 1 and 0. (2) Almanac data and Almanac health When the SV ID is a value between 1 and 32, the content of that subframe comprises Almanac data and Almanac health. When the data ID is 11, the content is QZS Almanac data and Almanac health, and the eight bits of “data ID (2 bits) + SV ID (6 bits) “indicates the PRN number of the QZS. When the data ID is 00, the content is GPS Almanac data and Almanac health. The Almanac data and Almanac health for a GPS satellite that is visible (or has the potential to be visible) in at least the area shown in Section 4.1.1 are retransmitted. (a) Almanac data Almanac data are entered in the sections of word 5 that do not include bits 17 – 24. The parameter characteristics (number of bits, LSB scale factor, unit etc.) of Almanac data is the same as in Section 20.3.3.5.1.2 of Applicable Document (1). The eccentricity (e) means offset from 0.06 and the reference value of the inclination is 0.25 [semi circles], which is different from the GPS definition. The Almanac data for the QZS are updated approximately once every 3.5 days. The velocity calculated by the Almanac data is accurate within 30 m/s The GPS Almanac data are GPS Almanac data gathered by the QZSS Monitor Stations. The user algorithm is described in Section 6.3.6. (b) Almanac Health Almanac health is transmitted at the same time as Almanac data and is entered from bit 17-24 of word 5. This 8-bit Almanac health is divided into the first 3 bits and the last 5 bits. Definition of the first 3 bits are as shown in Section5.1.2.1.3.4. The last 5 bits are as shown in Section 5.1.2.1.3.3. The QZSS Master Control Station (MCS) constantly monitors the status of not only the QZS satellites but also other satellite positioning systems including GPS. The MCS makes judgments regarding normal or error status and generates Almanac health data, and provides these data to the user as reference data within the seconds, which is specified in Section 4.3.2.2. (3) Satellite Health When the Data-ID=00 and the SV-ID=51, 63, and when the Data-ID=11 and the SV-ID=49, 50, 51, the content of that subframe indicates the satellite health. Satellite health comprises 6 bits for each satellite. The satellite health for multiple satellites is included in the subframe. This 6 bits satellite health is divided into the first 1 bit and last 5 bits. The definition of the first 1-bit health is shown in section 5.1.2.1.3.4, and the definition of the last 5-bits health is shown in section 5.1.2.1.3.3. The format and structure of the subframe is defined as same as the one defined in Applicable Document (1), and the sequence in the subframe is shown in Table 5.2.2-2. IS-QZSS Ver. 1.4 61 Table 5.2.2-2 Sequence of Satellite Health in the frame when Data-ID=11 Satellite Health Area Data ID=11 SV ID=49 Data ID=11 SV ID=50 Data ID=11 SV ID=51 SV1 GPS PRN1 GPS PRN25 QZS PRN193 SV2 GPS PRN2 GPS PRN26 QZS PRN194 SV3 GPS PRN3 GPS PRN27 QZS PRN195 SV4 GPS PRN4 GPS PRN28 QZS PRN196 SV5 GPS PRN5 GPS PRN29 QZS PRN197 SV6 GPS PRN6 GPS PRN30 Spare SV7 GPS PRN7 GPS PRN31 Spare SV8 GPS PRN8 GPS PRN32 Spare SV9 GPS PRN9 Spare Spare SV10 GPS PRN10 Spare Spare SV11 GPS PRN11 Spare Spare SV12 GPS PRN12 Spare Spare SV13 GPS PRN13 Spare Spare SV14 GPS PRN14 Spare Spare SV15 GPS PRN15 Spare Spare SV16 GPS PRN16 Spare Spare SV17 GPS PRN17 Spare Spare SV18 GPS PRN18 Spare Spare SV19 GPS PRN19 Spare Spare SV20 GPS PRN20 Spare Spare SV21 GPS PRN21 Spare Spare SV22 GPS PRN22 Spare Spare SV23 GPS PRN23 Spare Spare SV24 GPS PRN24 Spare Spare When the SV-ID=51 and the Data-ID=11, it indicates the QZS satellite health. When the SV-ID=49 or 50 and the Data-ID=11, it indicates the health of GPS as judged by QZSS monitoring stations. The 24 MSBs of words 4 through 9 provide the satellite health status for 24 satellites to users. When the SV-ID=51 and the Data-ID=00, the contents is the same as the message in the case of SV-ID=49 and Data-ID=11. Therefore the combination of SV-ID=51 and Data-ID=00 won’t be used in future. When the SV-ID=63 and the Data-ID=00, the contents are A-S flag and Satellite flag for GPS PRN25-32). The structure of the message is same as that in Figure 20-1 (Sheet 9 of 11) of applicable document (1). Since the satellite health data for GPS (PRN 25-32) are also included in the message of SV-ID=51 and Data-ID=11, the combination of SV-ID=63 and Data-ID=00 won’t be used in future. Health data are also provided in subframe 1. Data for other satellites provided by means of subframes 1, 4 and 5 are uploaded at a different time, so it may differ from the data in subframes 4 and 5. The QZSS MCS constantly monitors the status of not only the QZS but other satellite positioning systems including GPS. The MCS judges whether the system is in normal or error status and then generates satellite health data and provides the data to the user within the seconds, which is specified in Section 4.3.2.2 for use as reference data. IS-QZSS Ver. 1.4 62 (4) Anti-Spoof flag and satellite configuration When the SV ID is 63 and the data ID is 00, a 4-bit code (capacity for 32 items) is provided, indicating the GPS A-S status and configuration. This code is the same as in Section 20.3.3.5.1.4 of Applicable Document (1), and it constitutes a rebroadcast of the GPS AS flag and satellite configuration acquired by the QZSS MS. The combination of SV-ID=63 and Data-ID=00 won’t be used in future (5) Almanac Reference Week Number When the SV-ID=51 & DATA-ID=00, or when SV-ID=49~51 & DATA-ID=11, bits 17 - 24 in word 3 indicate the Week Number (WN a ) that serves as a reference for the Almanac Reference Time (t oa ) (see Section 20.3.3.5.1.2 and 20.3.3.5.2.2 of Applicable Document (1)). When the Data ID is 00 & SV-ID=51, or when Data-ID=11 & SV-ID=49 or 50, they indicate GPS Almanac Reference Week Number; when the Data ID is 11 & SV-ID is 51, it indicates a QZS Almanac Reference Week Number. WN a is made up of 8 bits and is a modulo-256 expression of the GPS Week Number (see Section 6.3.6) used as a reference. Word 3 indicates the t oa referenced by WN a . When the Data-ID = 11 & SV-ID = 51, it indicates that the Almanac Reference Week Number is auxiliary data. In other words, if the current time, t, is near the weekend and the t oa for the Almanac data is at the beginning of the week, the Almanac Reference Week is the following week. Moreover, if the current time is at the beginning of the week and the t oa for the Almanac data is on the weekend, the Almanac Reference Week is the previous week. In other cases, the Almanac Reference Week is the current week. When the Data-ID = 00 and SV-ID = 51 or Data-ID=11 & SV-ID=49 or 50, the Almanac Reference Week Number is the same as in Section 20.3.3.5.1.5 of Applicable Document (1), and it constitutes a rebroadcast of the GPS Almanac Reference Week Number acquired by the QZSS MS. GPS almanac reference week number and almanac reference time broadcasted in the case of Data-ID=00 & SV-ID=51 are same as the message in the case of Data -ID=11 and Sat-ID=49 or 50. Therefore the combination of SV-ID=51 & Data-ID=00 won’t be used in future. (6) Coordinated universal time parameter When the SV ID is 56, the 24 MSBs of words 6 - 9 and the 8 MSBs of word 10 contain the parameters for correcting UTC time to match GPS time. When the data ID is 00, it indicates a GPS rebroadcast, (the parameters to calculate the time offset between UTC (USNO) and GPS time). When the data ID is 11, it signifies the parameters to calculate the time offset between UTC (NICT) (with QZSS as the standard) and GPS time. The number of bits, scale factor, range and units are the same as in Table 20-IX of Applicable Document (1). The user algorithm is as noted in Section 6.3.7. The accuracy of the Coordinated Universal Time (UTC) parameter when the data ID is 00 or 11 is 90 [ns]. IS-QZSS Ver. 1.4 63 (7) Ionospheric parameter When the SV ID is 56, bits 9 - 24 in word 3 and the 24 MSBs of words 4 and 5 indicate the ionospheric parameters for use in the ionospheric model employed by users of only the L1C/A signal, LIC signal, L2C signal or L5 signal to calculate the ionospheric delay. When the data ID is 00, it indicates a GPS rebroadcast and the parameter is applicable worldwide. When the data ID is 11, it indicates that the ionospheric parameters have been generated by QZSS, and that the parameters have been specialized and are applicable within the area shown in Figure 4.1.5-1. These parameters usually, except ionospheric disturbance, use data for the past 24 hours (maximum) and are updated at least once each day. The number of bits, scale factor, range and units are the same as in Section 20.3.3.2.5 and Table 20-X of Applicable Document (1). For the user algorithm for users of only one signal, first the internal signal group delay error is corrected in accordance with Section 6.3.4, and then the ionospheric correction is performed in accordance with Section 6.3.8. (8) Navigation Message Correction Table (NMCT) When the SV-ID=52~54 & DATA-ID=11, this indicates a Navigation Message Correction Table (NMCT). When the SV ID is 52, it indicates ERD values for GPS (PRN1 – PRN30). When the SV ID is 53, it indicates ERD values for QZSS (PRN193 - PRN197) and GPS (PRN31 & 32). When the SV ID is 54, it reserved for spares. The format and structure of the subframe is defined as same as the one defined in Applicable Document (1), and the sequence in the subframe is shown in Table 5.2.2-3. IS-QZSS Ver. 1.4 64 Table 5.2.2-3 Sequence of NMCT in the frame when Data-ID=11 ERD Area Data ID=11 SV ID=52 Data ID=11 SV ID=53 Data ID=11 SV ID=54 ERD1 GPS PRN1 QZS PRN193 Spare ERD2 GPS PRN2 QZS PRN194 Spare ERD3 GPS PRN3 QZS PRN195 Spare ERD4 GPS PRN4 QZS PRN196 Spare ERD5 GPS PRN5 QZS PRN197 Spare ERD6 GPS PRN6 GPS PRN31 Spare ERD7 GPS PRN7 GPS PRN32 Spare ERD8 GPS PRN8 Spare Spare ERD9 GPS PRN9 Spare Spare ERD10 GPS PRN10 Spare Spare ERD11 GPS PRN11 Spare Spare ERD12 GPS PRN12 Spare Spare ERD13 GPS PRN13 Spare Spare ERD14 GPS PRN14 Spare Spare ERD15 GPS PRN15 Spare Spare ERD16 GPS PRN16 Spare Spare ERD17 GPS PRN17 Spare Spare ERD18 GPS PRN18 Spare Spare ERD19 GPS PRN19 Spare Spare ERD20 GPS PRN20 Spare Spare ERD21 GPS PRN21 Spare Spare ERD22 GPS PRN22 Spare Spare ERD23 GPS PRN23 Spare Spare ERD24 GPS PRN24 Spare Spare ERD25 GPS PRN25 Spare Spare ERD26 GPS PRN26 Spare Spare ERD27 GPS PRN27 Spare Spare ERD28 GPS PRN28 Spare Spare ERD29 GPS PRN29 Spare Spare ERD30 GPS PRN30 Spare Spare The NMCT begins with a 2-bit term indicating availability (AI), followed by a 6-bit ERD value consisting of up to 30 items. (a) AI (Availability Indication) The AI is made up of bits 9 and 10 of Word 3. 00: Correction table is decoded and can be used 01: Spare 10: Correction table cannot be used 11: Spare (b) ERD (Estimated Range Deviation) With regard to the NMCT ERD value, the MSB is the sign bit, while the LSB indicates 0.3 m, and the data range is ±9.3 m. A binary value of “100000” indicates that the ERD value does not exist. A binary value of “011111” indicates that the ERD value exceeds the upper limit. The user algorithm is as noted in Section 6.3.9.1. IS-QZSS Ver. 1.4 65 5.3 L1C Signal 5.3.1 RF Characteristics 5.3.1.1 Signal Configuration Figure 5.3.1-1 shows the configuration of the L1C signal. The L1C signal is modulated onto the L1 RF carrier (in a similar way, but separately from, the L1 C/A and L1-SAIF QZSS signals) as specified in Section 5.1. This section specifies how the bit streams are generated for the two L1C signals: the L1C data signal (L1CD) and the L1C pilot (data-less) signal (L1CP). The L1CD bit stream is generated by the modulo-2 addition (XOR) of the L1C navigation message and the L1CD PRN ranging code. The L1CP bit stream is generated by the modulo-2 addition (XOR) of the L1C overlay code and the L1CP PRN ranging code. Each unique L1C PRN ranging code is at a chipping rate of 1.023 Mcps with a chip length of 10230 bits and a duration of 10 milliseconds. The L1CP overlay code is at a chipping rate of 100 bps with a chip length of 1800 bits and a duration of 18 seconds. The L1C navigation message is divided into three subframes (Time of Interval (TOI), Clock & Ephemeris (C&E) and Variable Data (Var)) that are Bose, Chaudhuri, and Hocquenghem (BCH) and 24-bit Cyclic Redundancy Check (CRC24) encoded. Subframes C&E and Var are further Low Density Parity Check (LDPC) encoded and subjected to interleaving. Then these subframes are integrated with the TOI subframe that has been BCH encoded. Inner FEC ½ Coder (LDPC) Inter- leaver 2 nd PRN as Overlay Code 100cps 1800chipL 1 st PRN as Ranging Code 1.023Mcps 10230chipL Outer FEC Coder (CRC 24) CNAV2 (100sps) L1C P L1C D TOI (9bits) C&E (576bits) Var (250bits) Outer FEC Coder (CRC 24) Outer FEC Coder (BCH 952) Inner FEC ½ Coder (LDPC) 600bits 274bits 1200bits {s;p1;p2} 548bits {s;p1;p2} 1748bits 52bits 1800bits/18sec L1CP(t) L1CD(t) L1CO(t) Figure 5.3.1-1 L1C Signal Structure 5.3.1.2 Carrier Wave Properties In accordance with Section 5.1. IS-QZSS Ver. 1.4 66 5.3.1.3 Code Properties 5.3.1.3.1 Overview of Code As noted in Sections 5.3.1.1, there are two types of PRN code used for the L1C signals: unique PRN ranging codes for L1CD and L1CP, and an overlay code for L1CP. The methods used to generate both types of code are the same as the methods specified in Applicable Document (3). Specifically, the method noted in Section 3.2.2.1.1 of Applicable Document (3) is used to generate the PRN ranging codes. With regard to the specific L1C PRN numbers for the L1CD and L1CP signals to be broadcast by each QZS from among those numbers listed in Section 6.3.1.1 of Applicable Document(3), the numbers specified in Section 5.1.1.11.1 of this IS-QZSS document are to be used. Similarly, the method noted in Section 3.2.2.1.2 of Applicable Document (3) is used to generate the overlay codes. With regard to the specific PRN numbers for the overlay code of the L1CP signal to be broadcast by each QZS from among the numbers listed in Section 6.3.1.2 of Applicable Document (3), the numbers specified in Section 5.1.1.11.1 of this IS-QZSS document are to be used. For this reason, an S2 polynomial expression is needed for Fig. 3.2-2 in Section 3.2.2.1.2 of Applicable Document (3). 5.3.1.3.2 Non-Standard Code In the event that a problem with the QZSS occurs, a non-standard code (NSC) is transmitted. This is done to protect the user by ensuring that users do not use erroneous signals. 5.3.2 Messages 5.3.2.1 Message Configuration As noted in Section 5.3.1.1 in this manual, navigation messages are divided into three subframes: TOI, C&E, and Var. This message configuration is the same as specified in Section 3.2.3.1 of Applicable Document (3). 5.3.2.2 Encoding As noted in Section 5.3.1.1 above, navigation messages are divided into three subframes: TOI, C&E and Var. Each of these subframes is BCH and CRC24 encoded. Furthermore, C&E and Var are further subjected to LDPC encoding. The encoding process used for these subframes is the same as specified in Sections 3.2.3.2 – 3.2.3.4 of Applicable Document (3). 5.3.2.3 Interleaving As noted in the previous section, the C&E and Var subframes that are subjected to LDPC encoding are also interleaved and then integrated with the TOI subframe that has been BCH encoded. The interleaving process is the same as in Section 3.2.3.5 of Applicable Document (3). IS-QZSS Ver. 1.4 67 5.3.2.4 Message Content With the exception of the list in Section 8.1.3, the content of the L1C message for QZSS is the same as that for GPS as specified in Section 3.5 of Applicable Document (3). 5.3.2.4.1 TOI (Subframe 1) Prior to encoding, the TOI subframe is made up of 9 bits. TOI is incremented by 1 at each message period (= 18 seconds). TOI reverts to 0 every two hours. The valid range is 0-399. The initial TOI value for a two-hour period is 1. The final TOI value for a two-hour period is 0. These values are the same as the values specified in Sections 3.5.1 and 3.5.2 of Applicable Document (3). 5.3.2.4.2 C&E (Subframe 2) Prior to encoding, C&E (subframe 2) is composed of 576 bits. The C&E data is used to calculate the orbital position and time of the QZS. This subframe includes the Ephemeris data, etc. for the satellite, such as the data shown in Table 5.3.2-1. For an overview, see Section 3.5.3 of Applicable Document (3). In all other respect except as specified in Section 3.1.2.1.2 and (10) in this section “Integrity Assurance”, this subframe is the same as specified in Section 3.5.3 of Applicable Document (3). IS-QZSS Ver. 1.4 68 Table 5.3.2-1 Definition of Ephemeris parameters and SV clock parameters for Navigational Message D L1C Parameter Definition Difference from GPS definition WN n GPS Week Number ITOW Interval time of week (ITOW) count defined as being equal to the number of two-hour epoch that has occurred since the transition from the previous week. t op Data predict time of week (seconds into week) L1C Health L1C signal health URA oe index Ephemeris accuracy Index. t oe Ephemeris epoch (seconds into week) AA Difference from Semi-Major Axis at t oe In the case of QZS, indicates difference with 42,164,200 [m] In the case of GPS, indicates difference with 26,559,710 [m] A  Change rate in Semi-Major Axis An 0 Difference from mean motion calculation at t oe 0 n A Change rate in mean motion of calculation M 0-n Mean anomaly at t oe e n Eccentricity QZSS does not limit the numerical range (In GSS, Maximum value = 0.03). ω n Argument of perigee Ω 0-n Longitude of ascending node at the beginning of the week O A  Rate of right ascension of ascending node (RAAN) difference from reference value *1 i 0-n Orbit inclination at t oe i o-n -DOT Change rate in Orbit inclination C is-n Amplitude of the sine harmonic correction term to the angle of inclination C iｃ-n Amplitude of the cosine harmonic correction term to the angle of inclination C ｒs-n Amplitude of the sine correction term to the orbit radius C ｒc-n Amplitude of the cosine correction term to the orbit radius C us-n Amplitude of the sine harmonic correction term to the argument of latitude C uc-n Amplitude of the cosine harmonic correction term to the argument of latitude URA oc index SV clock accuracy index URA oc1 index SV clock accuracy change index URA oc2 index SV clock accuracy change rate index a f2-n SV clock drift rate correction term a f1-n SV clock drift correction term a f0-n SV clock bias correction term T GD LC QZSS *2 and L1C/A group delay LC GPS *3 and L1P(Y) group delay for GPS ISC L1CP L1C/A-L1CP group delay L1P(Y) – L1CP for GPS ISC L1CD L1C/A-L1CD group delay L1P(Y) – L1CD for GPS IS-QZSS Ver. 1.4 69 *1 Relative to ] cond circles/se - semi [ 10 6 . 2 9 ÷ × ÷ = O REF  (same value with GPS) *2 LC QZSS ： LC QZSS is the ionospheric error free linear combination of the L1C/A and L2C signals for QZSS *3 LC GPS ： LC GPS is the ionospheric error free linear combination of the L1P(Y) and L2P(Y) signals for GPS (1) Transmission Week No. Bits 1-13 of subframe 2 constitute a binary expression for the modulo-8192 representation of the current GPS Week Number. This is the same as in Section 3.5.3.1 of Applicable Document (3). (2) ITOW （Interval Time Of Week） Bits 14-21 of subframe 2 constitute a number that is incremented by 1 every two hours starting from the beginning of the GPS week. The valid range is 0-83. The ITOW value for the two-hour period just prior to the week changeover is 83. The ITOW value for the first two-hour period of the week is 0. This is the same as in Section 3.5.3.2 of Applicable Document (3). The calculated “time of week” using TOI defined in Section 5.3.2.4.1 and ITOW is not always same as actual GPS time. This inconsistency occurs every two hours. End/Start of week (GPS time) 2-hour epoch TOI=1 ITOW=0 WN=2 TOI=0 ITOW=83 WN=1 TOI=0 ITOW=0 WN=2 TOI=1 ITOW=1 WN=2 18 seconds time TOI=399 ITOW=83 WN=1 2-hour epoch 1week, 604782s 1week, 597600s 2week, 18s 2week, 0s 2week, 7218s 1week, 604764s 2week, 0s 2week, 7182s 2week, 7200s 1week, 604782s Actual GPS Time Corresponding time to the message 2week, 7218s same NOT same ! The corresponding time to the message dose not increase continuously . NOT same ! Figure 5.3.2-1 Relationship between TOI, ITOW & time of week (3) t op (time at which Ephemeris data estimate is made) Bits 22-32 of subframe 2 represents the time at which the Ephemeris data estimate is made (t op ). This is the same as in Section 3.5.3.3 of Applicable Document (3). IS-QZSS Ver. 1.4 70 (4) Signal Health (L1) The single bit 33 of subframe 2 indicates the health of the L1C signal transmitted by the satellite. Signal health is expressed as follows. 0 No problems with signal 1 Problem with signal exists or signal cannot be used As an operation specific to the QZSS, this bit expresses the result of a comparison with the present status of the satellite as determined through monitoring. For more information, see Section 5.1.2.1.3. Additional SV health data are present on pages 3 and 4 of subframe 3 as well. The data in message type 10 are uploaded at a different time, so these data may differ from the data for the satellites transmitting other messages and other satellite data. In all other respects, this is the same as in Section 3.5.3.4 of Applicable Document (3). (5) Ephemeris Data Accuracy Indicator (URA oe Index) Bits 34-38 of subframe 2 indicate the SIS accuracy indicator of the Ephemeris data. For more information, see Section 5.1.2.1.3.2. In all other respects, this is the same as in Section 3.5.3.5 of Applicable Document (3). (6) Ephemeris Data The Ephemeris data for the corresponding satellite shown in Table 5.3.2-1 are transmitted in Subframe 2. The algorithm used to determine the orbital position of the satellite is in accordance with Section 6.3.5. With the exception of the QZSS-unique semi major axis parameter (specified in (a) below), the ephemeris data characteristics (number of bits, LSB scale factor, data range and units) are the same as in Table 3.5-1 of Applicable Document (3). The data structure (data sequence etc.) is the same as in Fig. 3.5-1 of Applicable Document (3). (a) Semi Major Axis Difference AA AA is the difference between the QZS semi major axis at t oe A (t oe ) and 42,164,200 [m]: AA (t oe ) = A (t oe )-42,164,200 [m] (7) Clock Parameters The SV clock parameters for the satellite, shown in Table 5.3.2-1, are transmitted. The user algorithm is the same as in Section 20.3.3.3.3.1 of Applicable Document (1). However, some of the parameter definitions are different. For more information, see Section 6.3.2. The epoch t oe in the ephemeris data contained in bit 39-49 of subframe 2 is used as the epoch for the clock parameters. This is the same as in Section 3.5.3.7 of Applicable Document (3). IS-QZSS Ver. 1.4 71 (8) URA oc Index (accuracy indicator for SV clock parameters) Bits 460-470 of subframe 2 contain the parameters needed to determine URA oc , which indicates the SIS accuracy of the SV clock parameters. For more information, see Section 5.1.2.1.3.2. With regard to the epoch for the accuracy indicator of the SV clock parameters, bits 22-32 of subframe 2 use the time t op estimated by the Ephemeris data. This is the same as in Section 3.5.3.8 of Applicable Document (3). The algorithm used to determine the specific user range accuracy (URA oc ) expressed by URA oc index is the same as in Section 3.5.3.8 of Applicable Document (3). For more information about the method of use and the content of URA oc , see Sections 3.1.2.1.3 and 5.1.2.1.3, respectively. Note: Refer to the above applicable document (3), URA oc is calculated in quadratic equation of the time. The coefficient of the linear term and that of quadratic term would become larger than 0 by definition. The value of the linear term would become larger than 1.7578 m after 3600 seconds from the t op because t op is updated every 3600 seconds for QZSS. (9) Calculation of Group Delay Error Bits 527-565 of subframe 2 constitute the parameters T GD , ISC L1CP and ISC L1CD used to calculate the group delay error for users of only the L1C signal (i.e., single-frequency users). The number of bits, scale factor, range and units are shown in Table 3.5-1 of Applicable Document (3). Bit string "1000000000000" indicates that the group delay value cannot be used. Related algorithms are shown in Sections 6.3.3 and 6.3.4. (10) Integrity Assurance One bit of bits 566 of subframe 2 of GPS is “Integrity Status Flag” (Refer to Applicable Document (3) Section 3.5.3.10). But QZS-1 does not adopt this Flag. Adding this one bit ISF to current QZSS L1C message after ”Phase Two” is under study. 5.3.2.4.3 Var (Subframe 3) Var (subframe 3) comprises 250 bits prior to encoding. This subframe is used to transmit other data using multiple pages. Subframe 3 begins with 8 bits (193-197) that indicate the QZS satellite number from which the signal is transmitted, followed by a 6-bit page number. This is the same as in Section 3.5.4 of Applicable Document (3). 5.3.2.4.3.1 PRN No. Bits 1-8 of subframe 3 constitute an 8-bit PRN number representing the PRN number for the QZS transmitting that message. This is the same as in Section 3.5.4 of Applicable Document (3). IS-QZSS Ver. 1.4 72 5.3.2.4.3.2 Page No. Bits 9-14 of subframe 3 constitute a 6-bit page number signifying the information contained in that frame. The relationship between the individual page numbers and the corresponding information is shown in Table 5.3.2-2. Details are shown in Section 5.3.2.4.3.3. Table 5.3.2-2 also shows the maximum intervals at which each individual parameter is transmitted. Multiple QZS satellites may use completely different timings to transmit the data identified by page numbers. As a result, when the signals from multiple QZS satellites are received, all data sets can be collected at periods that are shorter than the data set transmission period for a single QZS satellite. As noted in Section 3.5.5 of Applicable Document (3), each page is transmitted using an arbitrary timing, so users should not expect a set pattern. Table 5.3.2-2 Definition of page number and transmit periods for Navigational Message D L１C Page Message data Maximum Interval Notes 1 Ionospheric parameter, UTC parameter 288 seconds 2 GGTO (GPS–QZSS Time Offset), EOP 288 seconds 3 Reduced Almanac of QZSS 20 minutes 4 Midi Almanac of QZSS 120 minutes 5 Differential correction data (DC) [Ephemeris correction data, SV clock correction data］ 30 minutes (*) 6 Text As needed 7 Spare － 17 Ionospheric parameter, UTC parameter (GPS Rebroadcasting) * 18 GGTO (GPS–Galileo Time Offset) (GPS Rebroadcasting) * 19 Reduced Almanac of GPS (GPS Rebroadcasting) * 20 Midi Almanac of GPS (GPS Rebroadcasting) * * We will not define the maximum transmit period for GPS rebroadcasting parameters and GPS DC data. IS-QZSS Ver. 1.4 73 5.3.2.4.3.3 Content of Individual Pages (1) Page No. 1 (17): UTC parameters/Ionospheric parameters Page 1 (17) includes the UTC parameters and ionospheric parameters such as shown in Table 5.3.2-3. For an overview, see Section 3.5.4.1 of Applicable Document (3). Table 5.3.2-3 Definition of UTC parameters and Ionospheric parameters for Navigational Message D L１C Parameter Definition Difference from GPS definition U T C p a r a m e t e r s n A ÷ 0 Bias coefficient of GPST time scale relative to UTC time scale When page No. is 1: Parameters indicate UTC(NICT) When page No. is 17 (rebroadcast of GPS message): Parameters indicates UTC(USNO) n A ÷ 1 Drift coefficient of GPST time scale relative to UTC time scale n A ÷ 2 Drift rate coefficient of GPST time scale relative to UTC time scale LS t A Current or past leap second count t t 0 Seconds into week for UTC and GPST bias calculation t WN 0 GPS Week Number for UTC and GPST bias calculation LSF WN GPS Week Number at the end of which the leap second becomes effective. DN Day number at the end of which the leap second becomes effective (First day number = 1). LSF t A Current or future leap second count I o n o s p h e r i c p a r a m e t e r s α 0 Ionospheric parameter α 0 for Klobuchar model When page No. is 1: Parameters are optimized for Japan & environs When page No. is 17 (rebroadcast of GPS message): Parameters can be applied on global area α 1 Ionospheric parameter α 1 for Klobuchar model α 2 Ionospheric parameter α 2 for Klobuchar model α 3 Ionospheric parameter α 3 for Klobuchar model β 0 Ionospheric parameter β 0 for Klobuchar model β 1 Ionospheric parameter β 1 for Klobuchar model β 2 Ionospheric parameter β 2 for Klobuchar model β 3 Ionospheric parameter β 3 for Klobuchar model ( G r o u p D e l a y P a r a m e t e r ) - - For GPS, Group Delay Parameters (ISC_L1CA, ISC_L2C, ISC_L5I5 and ISC_L5Q5) were added in Figure 3.5-2 of Applicable Document (3). While the message for QZS-1 did not adopt these parameters. IS-QZSS Ver. 1.4 74 (a) UTC Parameters The UTC parameters are the parameters needed to relate GPS time to UTC (NICT). The number of bits, scale factor, range, units, LSB, user algorithm, etc. are all the same as Section 3.5.4.1 in Applicable Document (3). (b) Ionospheric Parameters The ionospheric parameters are the parameters used when users of only one signal (L1, L2 or L5) employ an ionospheric model to calculate the ionospheric delay. The user algorithm for single signals is in accordance with Sections 6.3.4 and 6.3.8. The ionospheric parameters, optimized for the area near Japan, are specialized and apply to the area shown in Figure 4.1.5-1. These parameters use the data for the past 24-hour period (maximum) and are updated at least once daily, except ionospheric maximum period. The number of bits, scale factor, range and units are the same as Section 3.5.4.1.2 in Applicable Document (3). (c) Estimation of Group Delay Error For QZS-1, Bit 177 - 250 in page 1 of subframe 3 is defined as "Spare". On the other hand, for GPS, Group Delay Parameters (ISC_L1CA, ISC_L2C, ISC_L5I5 and ISC_L5Q5) were added at bit 171 - 228 in Page 1 of subframe 3 (Referred to Figure 3.5-2 in Applicable Document (3)). The message for QZS-1 did not adopt these parameters. Future supports for adoptions of the Group Delay Parameters in QZSS are under study. (2) Page No. 2 (18): GPS/GNSS Time Offset (GGTO) Parameters and Earth Orientation Parameters (EOP) Page 2 includes the GPS/GNSS Time Offset (GGTO) Parameters, parameters that are used to adjust GPS time to match other GNSS system times, as shown in Table 5.3.2-4, and the Earth Orientation Parameters (EOP) that indicate the relationship between the earth's rotational axis and the Japan satellite navigation Geodetic System (JGS). With regard to the content of these parameters, see Section 3.5.4.2 in Applicable Document (3). The bit definition, number of bits, scale factor (LSB), range and units are all the same as Table 3.5-4 and 3.5-5 in Applicable Document (3). At a minimum, the valid period for GPS GNSS Time Offset (GGTO) is at least 24 hours. Page 18 is rebroadcast of GPS message. IS-QZSS Ver. 1.4 75 Table 5.3.2-4 Definition of GPS GNSS Time Offset (GGTO) and EOP parameters for Navigational Message D L１C Parameter Definition Difference from GPS definition G N S S t i m e o f f s e t G G T O GGTO A 0 Bias coefficient of GPST time scale relative to other GNSS time scale GGTO A 1 Drift coefficient of GPST time scale relative to other GNSS time scale GGTO A 2 Drift rate coefficient of GPST time scale relative to other GNSS time scale GGTO t Seconds into GGTO reference week GGTO WN GGTO Reference Week Number GNSS ID See (a) in this section E a r t h o r i e n t a t i o n p a r a m e t e r s E O P EOP t Seconds into EOP reference week X PM X-Axis polar motion value at EOP t X PM dt d X-Axis polar motion drift at EOP t Y PM Y-axis polar motion value at EOP t Y PM dt d Y-axis polar motion drift at EOP t 1 UT A UT1-UTC difference at EOP t 1 UT dt d A Rate of UT1-UTC difference at EOP t (a) GNSS-ID Bits 15-17 define the other GNSS that apply the GPS GNSS Time Offset (GGTO) parameters. The three-bit definitions are as follows: 000 Data cannot be used 001 Galileo 010 GLONASS 011 QZSS 100-111 Spare (b) GPS/GNSS Time Offset (GGTO) The algorithms used to derive GPS GNSS Time Offset (GGTO) are the same as in Applicable Document (3). However, the SV clock parameter for the QZS already uses GPST as the standard, so the time offset between the GPS and QZSS (GQTO) is zero. (c) Earth Orientation Parameter (EOP) The definition, number of bits, scale factor, range, units, LSB, user algorithm etc, are all the same as Section 3.5.4.2.2 in Applicable Document (3). When page number is 18, i.e. the page for rebroadcasting GGTO in GPS CNAV message, since QZSS does not broadcast EOP obtained from GPS CNAV message, the information obtained from bits 83 to 220 cannot be used. IS-QZSS Ver. 1.4 76 (3) Page No. 3 (19): Reduced Almanac Page 3 includes the Reduced Almanac, as shown in Table 5.3.2-5. For an overview, see Section 3.5.4.3.5 in Applicable Document (3). The bit definition, number of bits, scale factor (LSB), range and units are all the same as Figure 3.5-9 and Table 3.5-6 in Applicable Document (3). When the PRN number is 63, the data packet includes dummy data without any effective information. The 22 bits are alternating ones and zeros, and the last 3 bits, which indicates the health, are all “1”s. The user algorithm is in accordance with Section 6.3.6. The Reduced Almanac is transmitted from a single satellite in a shorter period of time than the Midi Almanac. The Reduced Almanac data for the QZS are updated approximately once every 3.5 days. The velocity calculated by the Reduced Almanac data is accurate within 350 m/s. Page 19 is rebroadcast of GPS message. Table 5.3.2-5 Definition of Reduced Almanac parameters for Navigational Message D L１C Parameter Definition Difference from GPS definition WN a-n GPS Week Number at the time of Reduced Almanac generation t oa Reduced Almanac epoch (seconds into week) R e d u c e d A l m a n a c × 6 s a t e l l i t e s PRN No. PRN number (range 0 - 255) for satellite for which Reduced Almanac will be applied. 1-32 if target is GPS; 193-197 if target is QZSS δA Offset from the nominal QZS Semi-Major Axis of 42,164,200 [m] In the case of GPS, indicates the offset from 26,559,710 [m] Ω 0 Longitude of ascending node at the beginning of the week Φ 0 Argument of latitude （ = M 0 + ω） （e） Implicit eccentricity （0.075 in the case of QZS） （Precondition for above parameter） 0 in the case of GPS （δ i ） Fixed at -0.0111 [semi-circles], the offset from reference QZS orbit inclination of 0.25 [semi-circles] （precondition for above parameter） In the case of GPS, fixed at 0.0056 [semi-circles], the offset from 0.3 [semi-circles] L1/L2/L5 Health L1,L2 and L5 signal health ( e) Implicit Argument of Perigee (270[deg] in QZS-1） （Precondition for above parameters） 0[deg] in case of GPS IS-QZSS Ver. 1.4 77 (a) Reduced Almanac Epoch (Week Number) Bits 15-27 of subframe 3 indicate the Week Number (WN a-n ) corresponding to the Reduced Almanac epoch (t oa ). WN a-n is made up of 13 bits and is expressed by the modulo-8192 value for the GPS Week Number (see Section 6.3.6) that serves as a reference for t oa . This is the same as Section 3.5.4.3.1 in Applicable Document (3). (b) Reduced Almanac Epoch (seconds into week) Bits 28-35 of a subframe 3 indicate the Reduced Almanac epoch (t oa ). This is the same as Section 3.5.4.3.1 in Applicable Document (3). (c) 6 Reduced Almanac Packets Bits 36-233 of subframe 3 include six Reduced Almanac packets comprising 33 bits each. This is the same as Section 3.5.4.3.5 in Applicable Document (3). (d) PRN Number. Bits 1-8 in each packet constitute the PRN number for the satellite indicated by that packet. The PRN number constitutes 8 bits and expresses a value from 0 to 255. The definition of these values is as follows. 1-32: GPS PRN No. 65-94: The value minus 64 indicates a Galileo PRN No. 129-160: The value minus 128 indicates GLONASS PRN No. 193-197: QZSS PRN No. (e) Semi major axis Bits 9-16 in each packet provide the data (δA) relating to the semi major axis of the satellite indicated by the PRN number. - For PRN No. 193-197 (QZSS): A m A o + = ] [ 200 , 164 , 42 - For PRN No. 1-32 (GPS): A m A o + = ] [ 710 , 559 , 26 (f) Longitude of Ascending Node at the beginning of the week Bits 17-23 in each packet are the longitude of ascending node (Ω 0 ) at the beginning of the week for the satellite indicated by the PRN number. This is the same as Figure 3.5-9 in Applicable Document (3). (g) Argument of Latitude Bits 24-30 in each packet constitute the argument of latitude for the satellite indicated by the PRN number. This is the same as Figure 3.5-9 in Applicable Document (3). IS-QZSS Ver. 1.4 78 (h) Implicit Eccentricity For the eccentricity, although this is not broadcasted as Reduced Almanac from QZS, users may use the following assumption. - For PRN No. 193-197 (QZSS): 075 . 0 = e - For other PRN numbers: 0 . 0 = e (i) Implicit Inclination For the inclination, although this is not broadcasted as Reduced Almanac from QZS, users may use the following assumption. - For PRN No. 193-197 (Q2SS): i = 43 [deg] - For PRN No. 1-32 (GPS): i = 55 [deg] (j) Implicit Time Change Rate for Right Ascension of Ascending Node (RAAN) For the time change rate for the right ascension of ascending node (RAAN), although this is not broadcasted as Reduced Almanac from QZS, users may use the following assumption. - For PRN No. 193-197 (QZSS): ] cond circles/se semi [ 10 7 . 8 10 ÷ × ÷ = O ÷  - For PRN No. 1-32 (GPS): ] cond circles/se semi [ 10 6 . 2 10 ÷ × ÷ = O ÷  (k) Signal Health (L1/L2/L5) The three one-bit health indicators (bits 31, 32 and 33) in each packet relate to the corresponding L1, L2 and L5 signals of the satellite with the associated PRN number. Their significance is in accordance with Section 5.1.2.1.3. (l) Implicit Argument of Perigee For the argument of perigee, although this is not broadcasted as Reduced Almanac from QZS, users may use the following assumption. - For PRN No. 193-197 (QZSS): [deg] 270 = e - For PRN No. 1-32 (GPS): [deg] 0 = e (4) Page No. 4 (20): Midi Almanac Page 4 includes a Midi almanac like the one shown in Table 5.3.2-6. For an overview, see Section 3.5.4.3.6 in Applicable Document (3). The bit definition, number of bits, scale factor (LSB), range and units are all the same as in Figure 3.5-5 and Table 3.5-7 in Applicable Document (3). The user algorithm is in accordance with Section 6.3.6. The Midi Almanac data for the QZS are updated approximately once every 3.5 days. The velocity calculated by the Midi Almanac data is accurate with 30m/s Page 20 is rebroadcast of GPS message. IS-QZSS Ver. 1.4 79 Table 5.3.2-6 Definition of Midi Almanac parameters for Navigational Message D L１C Parameter Definition Difference from GPS definition WN a-n GPS Week Number at time of Midi Almanac generation t oa Midi Almanac epoch (seconds into week) PRN No. PRN number (range 0 - 255) for satellite for which Midi Almanac will be applied. 1-32 if GPS; 193-197 if QZSS L1/L2/L5 Health L1,L2 and L5 signal health Δe Eccentricity （offset from reference eccentricity 0.06） In the case of GPS, the offset from reference eccentricity 0 Δi Offset from reference inclination 0.25 [semi-circles] （Offset from 0.25 [semi-circles]=45 [deg]） In the case of GPS, the reference inclination is 0.3 [semi-circles], which represents 54 [deg]. O  Change rate in Right ascension of ascending node (RAAN) A Square root of Semi-Major Axis Ω 0 Longitude of ascending node at the beginning of the week Ω Argument of perigee M 0 Mean anomaly a f0 SV Clock bias correction coefficient a f1 SV Clock drift correction coefficient (a) Midi Almanac Epoch (Week Number) Bits 15-27 indicate the Week Number (WN a-n ) corresponding to the Midi Almanac epoch (t oa ). WN a-n is made up of 13 bits and is expressed by the modulo-8192 for the GPS Week Number (see Section 6.3.6) that serves as a reference for t oa . This is the same as Section 3.5.4.3.1 in Applicable Document (3). (b) Midi Almanac Epoch (seconds into week) Bits 28-35 indicate the Midi Almanac epoch (t oa ). This is the same as Section 3.5.4.3.1 in Applicable Document (3). IS-QZSS Ver. 1.4 80 (c) PRN Number. Bits 1-8 in each packet constitute the PRN number for the satellite. The PRN number constitutes 8 bits and expresses a value from 0 to 255. Within this range, the number categories are as follows. 1 - 32: GPS PRN No. 65 - 94: The value minus 64 indicates a Galileo PRN No. 129 - 160: The value minus 128 indicates GLONASS PRN No. 193 - 197: QZSS PRN No. (d) Signal Health (L1/L2/L5) The three one-bit health indicators (bits 44, 45, 46) relate to the L1, L2 and L5 signals of the satellite corresponding to the PRN number. Their significance is in accordance with Section 5.1.2.1.3. (e) Content of Midi Almanac Data Bits 47-165 include the Midi Almanac data for one satellite. With the exception of the eccentricity and inclination described below, this is the same as Figure 3.5-5 in Applicable Document (3). (f) Eccentricity Bitts 47-57 provide data e o relating to eccentricity e for the satellite indicated by the PRN number. - For PRN no. 193-197 (QZSS): e e a o + = 06 . 0 - For other PRN numbers: e e a o = e a : Actual eccentricity value e o : Eccentricity value included in navigation message (g) Inclination Bitts 58-68 provide data i o relating to inclination for the satellite indicated by the PRN number. - For PRN no. 193-197 (QZSS): ] [ 25 . 0 circle semi i i a ÷ + = o - For other PRN numbers: ] [ 3 . 0 circle semi i i a ÷ + = o i a : Actual inclination value i o : Inclination value included in navigation message IS-QZSS Ver. 1.4 81 (5) Page No. 5: Differential Correction Data (DC data) Page 5 includes differential correction data (DC data) for one satellite, as shown in Table 5.3.2-7. This parameter provides the user with correction terms for the SV clock parameters and Ephemeris data transmitted by other satellites. DC data are packetized data comprising a 34-bit SV clock error (CDC) correction parameter and a 92-bit Ephemeris error (EDC) correction parameter. The CDC and EDC data form a pair; users must use CDC and EDC with the same t op-D and t OD as a pair. For a DC Data Type indicator, "0" indicates that the correction applies to CNAV2 data. "1" indicates that the correction applies to the navigation message for the L1C/A signal. The content of the data packet is the same as Section 3.5.4.4 in Applicable Document (3) and is shown in Table 5.3.2-7. The bit definition, number of bits, scale factor, range and units for DC data are the same as Section 3.5.4.4 in Applicable Document (3). If the DC data is not effective, the value of the PRN Number is set to “11111111” as Section 3.5.4.4.1 in Applicable Document (3). In this case, DC data type indicator is set to “0”. Table 5.3.2-7 Definition of DC data for Navigational Message D L１C Parameter Definition Difference from GPS definition ｔ op-D Prediction time of week for DC data (seconds in week) t OD Reference time of week for DC data (seconds in week) DC Data Type indicator １：For D L1C/A message 0：For D L１C message C D C PRN No. PRN No. (range 0 - 255) for satellite for which DC data will be applied. 1 – 32 if target is GPS; 193-197 if target is QZSS 0 f a o Bias correction term for SV clock 1 f a o Drift correction term SV clock UDRA index User Differential Range Accuracy (UDRA) index E D C PRN No. PRN No. (range 0 - 255) for satellite for which DC data will be applied. 1 – 32 if target is GPS; 193-197 if target is QZSS Aα α correction term for Ephemeris parameter Aβ β correction term for Ephemeris parameter Aγ γ correction term for Ephemeris parameter Ai Correction term for orbit inclination AΩ Correction term for right ascension of ascending node (RAAN) AA Correction term for Semi-Major Axis UD ． RA index UDRA rate index IS-QZSS Ver. 1.4 82 DC data include the following. The use of these data is in accordance with Section 3.1.2.1.3.4. (a) Time of DC data Estimation (t op-D ) “t op-D ” indicates the time (seconds into week) at which DC data are estimated. This is the same as Section 3.5.4.4.2 in Applicable Document (3). (b) DC Data Epoch (t OD ) “t OD ” indicates the epoch (seconds into week) of DC data. This is the same as Section 3.5.4.4.3 in Applicable Document (3). (c) Identification of Satellite PRN The 8-bit PRN specifies the satellite to which DC data applies. A PRN of 1-32 indicates GPS. A PRN of 193-197 indicates QZSS. When all of the bit values are "1," it indicates that there are no DC data in the data block. In such cases, as Section 3.5.4.4.1 in Applicable Document (3), alternate bit values of "1" and "0" are entered for the remaining data. (d) Use of CDC Data This is the same as Section 3.5.4.4.4 in Applicable Document (3). For more information, see Section 6.3.9.2. (e) Use of EDC Data This is the same as Section 3.5.4.4.4 in Applicable Document (3). For more information, see Section 6.3.9.2. (f) Accuracy of DC Data UDRA op-D and UDRA-DOT indicate the ranging accuracy after the DC data have been applied to the SV clock parameters and Ephemeris data. The bit definition, number of bits, etc., and user algorithms are the same as Section 3.5.4.4.4 and Table 3.5-10 in Applicable Document (3). The use of this value is in accordance with Section 3.1.2.1.3.5. (6) Page No. 6: Text Message Page 6 includes 29 eight-bit ASCII characters. All bit definitions, number of bits, etc., are in accordance with Figure 3.5-7 in Applicable Document (3). (7) Page No. 7: （Reserved） （Reserved）: Same as Section 3.5.4.6 in Applicable Document (3). IS-QZSS Ver. 1.4 83 5.4 L1-SAIF signal 5.4.1 RF characteristics 5.4.1.1 Signal configuration In accordance with Section 5.1. 5.4.1.2 Carrier wave properties In accordance with Section 5.1. 5.4.1.3 Code properties 5.4.1.3.1 Code attributes Same as in Sections 3.2.1.3 and 3.3.2.3 of Applicable Document (1). However, the PRN code is as described in Section 5.1.1.11.2 of this document. 5.4.2 Error Correction Code The data transmission rate for the L1-SAIF message is 250 bps. However, the data bits are encoded by the Forward Error Correction (FEC) generator resulting in a 500 sps message for transmission. The FEC encoding factor is ½ and the constraint length is 7. Figure 5.4.2-1 shows the FEC generator used for encoding. G1 register tap is selected for the first 2 msec of a 4 msec message stream for 250 bits and G2 tap is done for latter 2 msec message. Figure 5.4.2-1 FEC Generation Method 5.4.3 Message The content of the SAIF message broadcast using the L1-SAIF signal is specified below. 5.4.3.1 Message Configuration Each message in the L1-SAIF signal is made up of 250 bits and has the format shown in Figure 5.4.3-1. The data rate is 250 bps, so one message is transmitted every second. The 8-bit preamble begins from bit 1 of the 250-bit message. Next, the 6-bit message type identifier is inserted (bits 9-14). The 212-bit data domain begins from bit 15, and the 24-bit CRC parity begins from bit 227. The message transmission sequence is not specified; any message type may be transmitted during any one-second period. DATA INPUT (250 BPS) + + + + + + + + SYMBOL CLOCK G2 (133 OCTAL) OUTPUT SYMBOLS (500 SPS) ALTERNATING G1/G2 G1 (171 OCTAL) G1 is selected initially IS-QZSS Ver. 1.4 84 Figure 5.4.3-1 Message Block Format 5.4.3.1.1 Preamble The preamble added to the beginning of each message consists of the following three patterns repeated in sequence: Pattern A 01010011 Pattern B 10011010 Pattern C 11000110 The start of transmission of the first bit in the Pattern A preamble is synchronous with the epoch of the 6-second L1C/A signal navigation message subframe. The preamble of the next message to be transmitted after the message with the Pattern A preamble is Pattern B. After Pattern B comes Pattern C. After that, the sequence returns to Pattern A. FEC encoding is performed for preambles in the same manner as for the other bits in the message block. Accordingly, while the preamble indicates the beginning of the message block, it cannot be used for signal acquisition prior to FEC decoding or for bit synchronization. 212-BIT DATA FIELD 6-BIT MESSAGE TYPE IDENTIFIER (0-63) 8-BIT PREAMBLE OF 24 BITS TOTAL IN 3 CONTIGUOUS BLOCKS 24-BITS PARITY 250 BITS – 1 SECOND DIRECTION OF DATA FLOW FROM SATELLITE; MOST SIGNIFCANT BIT(MSB) TRANSMITTED FIRST 212-BIT DATA FIELD 6-BIT MESSAGE TYPE IDENTIFIER (0-63) 8-BIT PREAMBLE OF 24 BITS TOTAL IN 3 CONTIGUOUS BLOCKS 24-BITS PARITY 24-BITS PARITY 250 BITS – 1 SECOND DIRECTION OF DATA FLOW FROM SATELLITE; MOST SIGNIFCANT BIT(MSB) TRANSMITTED FIRST IS-QZSS Ver. 1.4 85 5.4.3.1.2 Message Type Each message has a 6-bit Message Type ID. Messages are identified by a Message Type ID ranging from 0 to 63. The content of the data field is defined as noted below according to the Message Type. Table 5.4.3-1 shows a list of message types. Table 5.4.3-1 SAIF Message Types Message Type ID Message Name Remarks 0 Test mode 1 PRN mask 2～5 Fast Correction & UDRE 6 Integrity data 7 (Fast Correction Degradation Factor) 10 Degradation Parameter 18 IGP mask 24 Mixed Fast/Long-term Correction 25 Long-term Correction 26 Ionospheric Delay & GIVE 28 Clock-ephemeris Covariance 40 ～ 51 Reservation for applications demonstration L1-SAIF+ Unique Message 52 TGP mask 53 Tropospheric Delay Correction 54～55 (Atmospheric delay correction) TBD 56 Inter Signal Bias Correction data 57 (Reserved for orbital information) TBD 58 QZS ephemeris Provisional 59 QZS Almanac data TBD 60 (Regional information/maintenance schedule) TBD 62 (Reserved for Inertial test) 63 Null message 5.4.3.1.3 CRC Parity A 24-bit CRC parity code is added to the end of the message. In the event of either a burst error or a random error causing a bit error rate of ≦ 0.5, the 24-bit CRC parity protects the message with an error miss rate ≦2 -24 ＝5.96×10 -8 . The following generating polynomial is used for CRC parity: ( ) 1 3 4 5 6 7 10 11 14 17 18 23 24 + + + + + + + + + + + + + = X X X X X X X X X X X X X X g User receivers must check the CRC parity of received messages. If there is a mismatch, the data in that message should not be used. 5.4.3.2 Use of Messages The method of using SAIF messages is specified below. IS-QZSS Ver. 1.4 86 5.4.3.2.1 QZS Selection When using SAIF messages, the SAIF message transmitted from a satellite that is currently in use should be used. Either of the following two methods may be used when switching satellites. (1) Parallel processing method: Before the changeover, the SAIF message being transmitted by the successor satellite is received and processed independently from the SAIF message being received from the current satellite. The changeover is initiated when all of the data needed for positioning have been successfully received from the successor satellite. (2) Serial processing method: The user receiver’s positioning output must be temporarily halted while changing satellites and all SAIF messages received from the former satellite must be deleted. Following the changeover, the SAIF message transmitted by the successor satellite is received and processed, and positioning output is resumed when all of the data needed for positioning have been successfully received from the successor satellite. The parallel processing method allows positioning output to be maintained continuously. However, at the time of changeover, both new and old SAIF messages must be processed in parallel. The serial method simplifies message processing, but positioning output cannot be continuous and must be stopped for several minutes. The serial method is similar to the processing performed following receiver power-on. 5.4.3.2.2 Minimum Elevation Angle The elevation angle of any satellite being used for augmentation data (via the QZSS SAIF message) must be at least 5° above the horizon as viewed from the user position. 5.4.3.2.3 Selection of Positioning Satellites and Signals Of the satellites for which QZSS provides augmentation data (via the SAIF message) and the satellites actually indicated by the PRN mask, the satellites used for positioning by the user receiver may be freely selected from among those that are above the specified 5° minimum elevation angle as viewed from the user position. Received QZS signals should be used in accordance with the following: (1) The L1 frequency signals may be used as long as they are indicated by the PRN mask. (2) Other frequencies can be used in place of the L1C/A signal for the same satellite after the Inter Signal Bias correction data in message type 56 have been applied. However, the ionospheric propagation delay must be corrected as needed in accordance with the frequency. 5.4.3.2.4 Numerical Expression Each data included in the SAIF message are expressed by fixed-point number representation. The specified bit sequence is transmitted from MSB to LSB and decimal point is located righthand of LSB. The necessary data can be obtained by multiplied integer value by resolution specified for each item. The two’s complement is used for expression of both plus and minus data. 5.4.3.3 Message Content (SBAS Compatible Message) 5.4.3.3.1 Message Type 0 (Test Mode) Message type 0 indicates that the L1-SAIF signal is in test mode. When a type 0 message has been received, the receiver should delete all SAIF messages received up to that point, and SAIF messages transmitted for the subsequent 60 seconds must also not be used. IS-QZSS Ver. 1.4 87 5.4.3.3.2 Message Type 1 (PRN Mask) Message type 1 contains a PRN mask. A PRN mask constitutes flag data that indicate a satellite for which augmentation data will be provided. Of the satellites in PRN slots 1 - 210, PRN masks may be set for up to 51 satellites. Satellites for which PRN masks have been set are assigned PRN mask numbers in sequence starting with the lowest PRN slot number. The range of PRN mask numbers is 1 - 51. In message types 25, 28 and 56 the target satellite is specified directly by the PRN mask numbers 1 - 51. In message types 2 - 7, the correspondence between the correction data slot and the PRN mask number is established in advance. Following the 210-bit PRN mask, a 2-bit PRN mask issue number (IODP) is transmitted. This number is incremented each time the PRN mask is updated (note that, since the IODP is only 2-bits, after 3 comes 0). Other message types that reference the PRN mask number include IODP corresponding to the PRN masks that should be used by receivers, so receivers should constantly monitor the PRN masks matching the IODP and convert them to PRN slot numbers. For QZSS, PRN mask updating differs from that specified in the Minimum Operational Performance Standards (MOPS) (Applicable Document (4)) and is not necessarily conducted only when a new satellite is launched or when a satellite goes out of service. In order to ensure the efficient use of message bandwidth, the combination of satellites for augmentation will be updated as needed. Other message types that reference the PRN mask number always require effective PRN masks, so before the IODP for other messages is updated, a new PRN mask is transmitted by means of message type 1. When a new PRN mask is received, the receiver retains both old and new PRN masks for some time, and consideration must be given to ensuring the use of the appropriate PRN mask until the IODP for other message types is updated. When the IODP for a message type other than type 1 has been updated, the old PRN mask may be deleted. In other words, different IODP are not retained just because the message type is different. If the IODP for a message type has been updated, all of the IODP for other message types that are transmitted are then updated. If a message type that references a new IODP appears before a message type 1 containing a new PRN mask has been received, that message type must not be used until a compatible PRN mask has been received. Once a new compatible PRN mask has been received, those messages may be used immediately. In order to protect against message type 1 reception failures, when the PRN mask is updated, message type 1 containing new PRN mask is transmitted at least four times over a period of 600 seconds before other message types that reference the new PRN mask are transmitted. In addition, PRN mask updating is never performed more frequently than once per hour. Table 5.4.3-2 Message Type 1: PRN Mask Data Repetitions Content Number of bits Resolution Effective Range Units 210 PRN mask 1 1 0～1 ― 1 IODP 2 1 0～3 ― IS-QZSS Ver. 1.4 88 Table 5.4.3-3 PRN Slot Assignments to GNSS Satellites PRN Slot Satellite System 1～37 GPS 38～61 GLONASS 62～119 (Spare) 120～138 SBAS 139～182 (Spare) 183 Quasi Zenith Satellite #1 L1-SAIF 184 Quasi Zenith Satellite #2 L1-SAIF 185 Quasi Zenith Satellite #3 L1-SAIF 186 Quasi Zenith Satellite #4 L1-SAIF 187 Quasi Zenith Satellite #5 L1-SAIF 188～192 Spare (for Quasi Zenith Satellite) 193 Quasi Zenith Satellite #1 L1C/A 194 Quasi Zenith Satellite #2 L1C/A 195 Quasi Zenith Satellite #3 L1C/A 196 Quasi Zenith Satellite #4 L1C/A 197 Quasi Zenith Satellite #5 L1C/A 198～202 Spare (for Quasi Zenith Satellite) 203～210 (Spare) 5.4.3.3.3 Message Types 2 - 5 (Fast Correction & UDRE) Message types 2 - 5 are used to transmit fast correction data. Each message has 13 correction data slots, each corresponding to the following PRN mask numbers: Message type 2 PRN mask no. 1 - 13 Message type 3 PRN mask no. 14 - 26 Message type 4 PRN mask no. 27 - 39 Message type 5 PRN mask no. 40 - 51 Slot 13 in message type 5 is not used. Each fast correction message type is transmitted only when needed by the number of satellites specified in the PRN mask. In other words, message type 5 is transmitted only when 40 or more satellites have been specified. The 12-bit fast correction (FC i ) is expressed as a two’s complement number (the MSB is the sign bit) and has a resolution of 0.125 m for the range of [-256.000 m, +255.750 m]. If this range is exceeded, FC i = 255.875 m and UDREI i = 15 will be set so as to prohibit use of fast correction. As message types 2 - 5 always have 13 correction slots, data for extra slots with no corresponding PRN mask numbers should never be used. The FC i valid time (t i,0f ) is the starting point for the second epoch of GPS time that matches the first bit of the message block. An "invalid" value for the fast correction value means that FC i = 255.875 or there is a time-out status. If fast correction is invalid or UDREI i =14-15, the associate satellite shall not be used for position computation. The UDREI i included in message types 2 - 5 and 24 indicates the σ 2 i,UDRE corresponding to the fast correction and is used to calculate the protection level. UDREI i = 15 indicates that the use IS-QZSS Ver. 1.4 89 of that satellite is prohibited. UDREI i may also be transmitted by message type 6. In such cases, IODF j shows the timing by which this corresponds to the FC i that is transmitted. Message types 2 - 5 and 24 include a 2-bit fast correction updating number (IODF j ). Here "j" indicates the message type number (2 - 5); in the case of message type 24, it indicates the message type (2 - 5) to which it corresponds. IODF j is used when calculating the degree of degradation of the fast correction time change rate RRC i , and to establish the correspondence with the UDREI i included in message type 6. If there is no alert status for any of the satellites in the correction slots, the range of the IODF j counter is 0 - 2 (incremented one by one; 2 is followed by 0). If an alert has been generated for one or more of the satellites in the correction slots, the IODF j value is set to 3. If IODF j = 3 has been transmitted, it indicates that the UDREI i included in that message type is used for all of the fast corrections that are effective (i.e., not in time-out status) at that time. If there are no more than 6 correction slots, message type 24 (combined fast & long-term corrections message) is used in place of message types 2 - 5. Table 5.4.3-4 Message Types 2 - 5: Fast Correction Repetitions Content Number of bits Resolution Effective Range Units 1 IODF j 2 1 0～3 ― 1 IODP 2 1 0～3 ― 13 FC i 12* 0.125 -256～ +255.75 m 13 UDREI i 4 (See Table 5.4.3-5) *: Parameters so indicated shall be in two’s complement notation. Table 5.4.3-5 UDRE value UDREI i σ 2 i,UDRE （m 2 ） UDREI i σ 2 i,UDRE （m 2 ） 0 0.0520 8 2.5465 1 0.0924 9 3.3260 2 0.1444 10 5.1968 3 0.2830 11 20.7870 4 0.4678 12 230.9661 5 0.8315 13 2078.695 6 1.2992 14 Not Monitored 7 1.8709 15 Do Not Use 5.4.3.3.4 Message Type 6 (Integrity Data) Message type 6 has been prepared to broadcast integrity data. The UDREI i for all satellites that are targeted for augmentation (for which a PRN mask has been set) are transmitted together using the format shown in Table 5.4.3-5 and Table 5.4.3-6. Message type 6 also includes an IODF j ; an updated number for the fast correction data is displayed for each of the 13 correction slots as in message types 2 - 5. IS-QZSS Ver. 1.4 90 Table 5.4.3-6 Message Type 6: Integrity Data Repetitions Content Number of bits Resolution Effective Range Units 1 IODF 2 2 1 0～3 ― 1 IODF 3 2 1 0～3 ― 1 IODF 4 2 1 0～3 ― 1 IODF 5 2 1 0～3 ― 51 UDREI i 4 (See Table 5.4.3-5) 5.4.3.3.5 Message Type 7 (Fast Correction Degradation Factor) Message type 7 is broadcast for maintaining compatibility, and described in Table 5.4.3-7. Table 5.4.3-7 Message Type 7: Fast Correction Degradation Factor Repetitions Content Number of bits Resolution Effective Range Units 1 System delay（t lat ） 4 1 0～15 s 1 IODP 2 1 0～3 ― 206 All zero 1 1 0 IS-QZSS Ver. 1.4 91 5.4.3.3.6 Message Type 10 (Degradation Parameter) Message type 10 has been designed to provide a degradation factor used to calculate the protection level. The parameters are as shown in Table 5.4.3-8. Table 5.4.3-8 Message Type 10: Degradation Parameter Repetitions Content Number of bits Resolution Effective Range Units 1 B rrc 10 0.002 0～2.046 m 1 C ltc_lsb 10 0.002 0～2.046 m 1 C ltc_v1 10 0.05 0～51.15 mm/s 1 I ltc_v1 9 1 0～511 s 1 C ltc_v0 10 0.002 0～2.046 m 1 I ltc_v0 9 1 0～511 s 1 C geo_lsb 10 0.5 0～511.5 mm 1 C geo_v 10 0.05 0～51.15 mm/s 1 I geo 9 1 0～511 s 1 C er 6 0.5 0～31.5 m 1 C iono_step 10 0.001 0～1.023 m 1 I iono 9 1 0～511 s 1 C iono_ramp 10 0.005 0～5.115 mm/s 1 RSS UDRE 1 1 0～1 ― 1 RSS iono 1 1 0～1 ― 1 C covariance 7 0.1 0～12.7 ― 1 C qzs_lsb 10 0.002 0～2.046 m 1 C qzs_v1 10 0.05 0～51.15 mm/s 1 I qzs_v1 9 1 0～511 s 1 C qzs_v0 10 0.002 0～2.046 m 1 I qzs_v0 9 1 0～511 s 1 IRI 3 1 0～4 ― 1 Spare 30 ― ― ― IS-QZSS Ver. 1.4 92 5.4.3.3.7 Message Type 18 (IGP Mask) As correction data for the ionospheric propagation delay, vertical delays corresponding to the predetermined ionosphere grid points (IGP) are transmitted. Message type 18 is used to specify the IGP that is currently the reference point for augmentation. Message type 18 must be received before ionospheric propagation delay correction is performed. Table 5.4.3-9 and Table 5.4.3-10 show the format and IGP content, respectively, for message type 18. The IGP is divided into 10 bands that are assigned band numbers 0 - 9. For each band, as many as 201 IGPs are defined, corresponding to slots 1 - 201. The order of IGP assignment for each band begins with slot number 1 in the southwest corner and increments from south to north along the same longitude. Once the northern edge is reached, it increments along the next eastward longitude from south to north and so on in sequence to assign the IGP slot numbers from 1 - 201. IGPs for which IGP masks have been set are divided into blocks of 15 (up to 14 blocks) in sequence by IGP mask number. IGP block 0 corresponds to IGP mask number 1 - 15, IGP block 1 corresponds to IGP mask number 16 - 30 and so on. The receiver need only collect correction data for the IGPs located at ± 20° in latitude and longitude from its location. If the number of bands transmitted by message type 18 is 0, it indicates that ionospheric propagation delay correction data are not provided. Message type 18 includes a 2-bit IGP mask update number (IODI). This number is incremented each time the IGP mask is updated (note that, since the IODI is only 2-bits, after 3 comes 0). Message type 26 includes an IODI that corresponds to the IGP mask that should be used by the receiver, so the receiver should constantly monitor the IGP mask that the IODI matches and convert it into an IGP slot number. IGP masks are almost never updated. Nevertheless, message type 26 always requires an effective IGP mask, so a new IGP mask is transmitted by means of message type 18 before the IODI for message type 26 is updated. When a new IGP mask is received, the receiver should retain both old and new IGP masks for some time. It is important to use the appropriate IGP mask while waiting for the IODI for message type 26 to be updated. In the event that a new message type 26 referencing a new IODI has appeared before a message type 18 containing a new IGP mask is received, that message type 26 must not be used until a compatible IGP mask is received. Once a compatible IGP mask has been received, the message type 26 may be used immediately. In order to prepare for message type 18 reception failures, when the IGP mask is updated, message type 18 is broadcast at least four times over a period of 600 seconds before a message type 26 referencing the new IGP mask is transmitted. In addition, IGP mask updating is never performed more frequently than once per hour. Table 5.4.3-9 Message Type 18 Format: IGP Mask Repetitions Content Number o bits Resolution Effective Range Units 1 No. of IGP bands 4 1 0～１１ ― 1 IGP band no. 4 1 0～１０ ― 1 IODI k 2 1 0～3 ― 201 IGP mask 1 ― 0～1 ― 1 IGP mask pattern 1 ― 0～1 ― IS-QZSS Ver. 1.4 93 Table 5.4.3-10 Specification of IGP locations (IGP mask pattern = 0) Band Longitude Latitude Slot No. 0 180W 75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N,85N 1～28 175W 55S,50S,45S,...,45N,50N,55N 29～51 170W 75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N 52～78 165W 55S,50S,45S,...,45N,50N,55N 79～101 160W 75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N 102～128 155W 55S,50S,45S,...,45N,50N,55N 129～151 150W 75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N 152～178 145W 55S,50S,45S,...,45N,50N,55N 179～201 1 140W 85S,75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N 1～28 135W 55S,50S,45S,...,45N,50N,55N 29～51 130W 75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N 52～78 125W 55S,50S,45S,...,45N,50N,55N 79～101 120W 75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N 102～128 115W 55S,50S,45S,...,45N,50N,55N 129～151 110W 75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N 152～178 105W 55S,50S,45S,...,45N,50N,55N 179～201 2 100W 75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N 1～27 95W 55S,50S,45S,...,45N,50N,55N 28～50 90W 75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N,85N 51～78 85W 55S,50S,45S,...,45N,50N,55N 79～101 80W 75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N 102～128 75W 55S,50S,45S,...,45N,50N,55N 129～151 70W 75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N 152～178 65W 55S,50S,45S,...,45N,50N,55N 179～201 3 60W 75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N 1～27 55W 55S,50S,45S,...,45N,50N,55N 28～50 50W 85S,75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N 51～78 45W 55S,50S,45S,...,45N,50N,55N 79～101 40W 75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N 102～128 35W 55S,50S,45S,...,45N,50N,55N 129～151 30W 75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N 152～178 25W 55S,50S,45S,...,45N,50N,55N 179～201 4 20W 75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N 1～27 15W 55S,50S,45S,...,45N,50N,55N 28～50 10W 75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N 51～77 5W 55S,50S,45S,...,45N,50N,55N 78～100 IS-QZSS Ver. 1.4 94 0 75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N,85N 101～128 5E 55S,50S,45S,...,45N,50N,55N 129～151 10E 75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N 152～178 15E 55S,50S,45S,...,45N,50N,55N 179～201 5 20E 75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N 1～27 25E 55S,50S,45S,...,45N,50N,55N 28～50 30E 75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N 51～77 35E 55S,50S,45S,...,45N,50N,55N 78～100 40E 85S,75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N 101～128 45E 55S,50S,45S,...,45N,50N,55N 129～151 50E 75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N 152～178 55E 55S,50S,45S,...,45N,50N,55N 179～201 6 60E 75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N 1～27 65E 55S,50S,45S,...,45N,50N,55N 28～50 70E 75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N 51～77 75E 55S,50S,45S,...,45N,50N,55N 78～100 80E 75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N 101～127 85E 55S,50S,45S,...,45N,50N,55N 128～150 90E 75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N,85N 151～178 95E 55S,50S,45S,...,45N,50N,55N 179～201 7 100E 75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N 1～27 105E 55S,50S,45S,...,45N,50N,55N 28～50 110E 75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N 51～77 115E 55S,50S,45S,...,45N,50N,55N 78～100 120E 75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N 101～127 125E 55S,50S,45S,...,45N,50N,55N 128～150 130E 85S,75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N 151～178 135E 55S,50S,45S,...,45N,50N,55N 179～201 8 140E 75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N 1～27 145E 55S,50S,45S,...,45N,50N,55N 28～50 150E 75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N 51～77 155E 55S,50S,45S,...,45N,50N,55N 78～100 160E 75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N 101～127 165E 55S,50S,45S,...,45N,50N,55N 128～150 170E 75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N 151～177 175E 55S,50S,45S,...,45N,50N,55N 178～200 9 60N 180W,175W,170W,...,165E,170E,175E 1～72 65N 180W,170W,160W,...,150E,160E,170E 73～108 70N 180W,170W,160W,...,150E,160E,170E 109～144 IS-QZSS Ver. 1.4 95 75N 180W,170W,160W,...,150E,160E,170E 145～180 85N 180W,150W,120W,...,90E,120E,150E 181～192 10 60S 180W,175W,170W,...,165E,170E,175E 1～72 65S 180W,170W,160W,...,150E,160E,170E 73～108 70S 180W,170W,160W,...,150E,160E,170E 109～144 75S 180W,170W,160W,...,150E,160E,170E 145～180 85S 170W,140W,110W,...,100E,130E,160E 181～192 (IGP mask pattern = 1) Band Longitude Latitude Slot No. 0 115E 15N,16N,17N,...,33N,34N,35N 1～21 116E 15N,16N,17N,...,33N,34N,35N 22～42 117E 15N,16N,17N,...,33N,34N,35N 43～63 118E 15N,16N,17N,...,33N,34N,35N 64～84 119E 15N,16N,17N,...,33N,34N,35N 85～105 120E 15N,16N,17N,...,43N,44N,45N 106～136 121E 15N,16N,17N,...,43N,44N,45N 137～167 122E 15N,16N,17N,...,43N,44N,45N 168～198 1 123E 15N,16N,17N,...,43N,44N,45N 1～31 124E 15N,16N,17N,...,43N,44N,45N 32～62 125E 15N,16N,17N,...,43N,44N,45N 63～93 126E 15N,16N,17N,...,43N,44N,45N 94～124 127E 15N,16N,17N,...,43N,44N,45N 125～155 128E 15N,16N,17N,...,43N,44N,45N 156～186 2 129E 15N,16N,17N,...,43N,44N,45N 1～31 130E 15N,16N,17N,...,48N,49N,50N 32～67 131E 15N,16N,17N,...,48N,49N,50N 68～103 132E 15N,16N,17N,...,48N,49N,50N 104～139 133E 15N,16N,17N,...,48N,49N,50N 140～175 3 134E 15N,16N,17N,...,48N,49N,50N 1～36 135E 15N,16N,17N,...,53N,54N,55N 37～77 136E 15N,16N,17N,...,53N,54N,55N 78～118 137E 15N,16N,17N,...,53N,54N,55N 119～159 138E 15N,16N,17N,...,53N,54N,55N 160～200 4 139E 15N,16N,17N,...,53N,54N,55N 1～41 140E 15N,16N,17N,...,53N,54N,55N 42～82 141E 20N,21N,22N,...,53N,54N,55N 83～118 142E 20N,21N,22N,...,53N,54N,55N 119～154 143E 20N,21N,22N,...,53N,54N,55N 155～190 IS-QZSS Ver. 1.4 96 5 144E 20N,21N,22N,...,53N,54N,55N 1～36 145E 20N,21N,22N,...,53N,54N,55N 37～72 146E 20N,21N,22N,...,53N,54N,55N 73～108 147E 20N,21N,22N,...,53N,54N,55N 109～144 148E 20N,21N,22N,...,53N,54N,55N 145～180 6 149E 20N,21N,22N,...,53N,54N,55N 1～36 150E 20N,21N,22N,...,53N,54N,55N 37～72 151E 25N,26N,27N,...,53N,54N,55N 73～103 152E 25N,26N,27N,...,53N,54N,55N 104～134 153E 25N,26N,27N,...,53N,54N,55N 135～165 154E 25N,26N,27N,...,53N,54N,55N 166～196 7 100E 75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N 1～27 105E 55S,50S,45S,...,45N,50N,55N 28～50 110E 75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N 51～77 115E 55S,50S,45S,...,45N,50N,55N 78～100 120E 75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N 101～127 125E 55S,50S,45S,...,45N,50N,55N 128～150 130E 85S,75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N 151～178 135E 55S,50S,45S,...,45N,50N,55N 179～201 8 140E 75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N 1～27 145E 55S,50S,45S,...,45N,50N,55N 28～50 150E 75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N 51～77 155E 55S,50S,45S,...,45N,50N,55N 78～100 160E 75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N 101～127 165E 55S,50S,45S,...,45N,50N,55N 128～150 170E 75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N 151～177 175E 55S,50S,45S,...,45N,50N,55N 178～200 9 110E 17.5N,22.5N,27.5N,32.5N,37.5N 1～5 112.5E 15N,17.5N,20N,...,35N,37.5N,40N 6～16 115E 17.5N,22.5N,27.5N,32.5N,37.5N 17～21 117.5E 15N,17.5N,20N,...,35N,37.5N,40N 22～32 120E 17.5N,22.5N,27.5N,32.5N,37.5N,42.5N 33～38 122.5E 15N,17.5N,20N,...,40N,42.5N,45N 39～51 125E 17.5N,22.5N,27.5N,32.5N,37.5N,42.5N 52～57 127.5E 15N,17.5N,20N,...,40N,42.5N,45N 58～70 130E 17.5N,22.5N,27.5N,32.5N,37.5N,42.5N,47.5N,52.5N 71～78 132.5E 15N,17.5N,20N,...,50N,52.5N,55N 79～95 135E 17.5N,22.5N,27.5N,32.5N,37.5N,42.5N,47.5N,52.5N 96～103 137.5E 15N,17.5N,20N,...,50N,52.5N,55N 104～120 IS-QZSS Ver. 1.4 97 140E 17.5N,22.5N,27.5N,32.5N,37.5N,42.5N,47.5N,52.5N 121～128 142.5E 15N,17.5N,20N,...,50N,52.5N,55N 129～145 145E 17.5N,22.5N,27.5N,32.5N,37.5N,42.5N,47.5N,52.5N 146～153 147.5E 20N,22.5N,25N,...,50N,52.5N,55N 154～168 150E 22.5N,27.5N,32.5N,37.5N,42.5N,47.5N,52.5N 169～175 152.5E 25N,27.5N,30N,...,50N,52.5N,55N 176～188 155E 27.5N,32.5N,37.5N,42.5N,47.5N,52.5N 189～194 IS-QZSS Ver. 1.4 98 5.4.3.3.8 Message Type 24 (Mixed Fast/Long-term Correction) Message type 24 may be used when the correction slot in message types 2 - 5 can only accommodate up to 6 items. Specifically, this occurs when the number of satellites subject to augmentation is 1 - 6, 14 - 19, 27 - 32 or 40 - 45. The first half of message type 24 contains the fast correction data in six slots. The 0 - 3 values for block ID correspond to message types 2 - 5, respectively, and specify the range of the PRN mask number to which the fast corrections in the six correction slots correspond. The method of use for the fast corrections is exactly the same as that for message types 2 - 5. The last half of message type 24 can accommodate half of the content of message type 25 (partial message). This allows long-term correction data for one or two satellites to be provided. Table 5.4.3-11 Message Type 24 (Fast & Long-term Corrections) Repetitions Content Number of bits Resolution Effective Range Units 6 FC i 12* 0.125 -256～+255.75 m 6 UDREI i 4 (See Table 5.4.3-5) 1 IODP 2 1 0～3 ― 1 Fast correction block ID 2 1 0～3 ― 1 IODF j 2 1 0～3 ― 1 Reserved 4 - - - 1 Partial message 106 (See Table 5.4.3-13) *: Parameters so indicated shall be in two’s complement notation. 5.4.3.3.9 Message Type 25 (Long-Term Correction) Message type 25 is broadcast to provide corrections for the clock and ephemeris long-term error. For GPS satellites, the clock and ephemeris that are the target for augmentation using QZS message type 25 must be calculated using the L1C/A navigation message (NAV message). The CNAV and CNAV2 messages must not be used. Message type 25 is made up of two partial messages. Each partial message has exactly the same format consisting of 106 bits. The partial message may include correction data for two satellites (velocity code = 0) or correction data for one satellite (velocity code = 1). In the former case (velocity code = 0), the message includes only corrections for clock offset and satellite position error. In the latter case, the message also includes the rates of change for clock offset and satellite positioning errors. Therefore, a message type 25 can accommodate long-term correction data for 2 - 4 satellites. Table 5.4.3-13 specifies the format for the two types of partial message corresponding to velocity code values of "0" and "1". The velocity codes for the two partial messages included in a single message of message type 25 can be different value. The PRN mask number (1 - 51) is defined by the PRN mask provided by message type 1. The IODP for the PRN mask must match. If the long-term correction data are invalid, "0" is set for the PRN mask number. Unlike message types 2 - 5, the positioning satellites augmented by message type 25 may not appear in sequential order, and there is no guarantee that the long-term corrections for each satellite will appear with the same frequency. Long-term correction data for satellites with rapidly changing long-term errors will be repeated with a greater frequency than the data of satellites with long-term errors that change more slowly. IS-QZSS Ver. 1.4 99 Table 5.4.3-12 Message Type 25: Long-Term Correction Repetitions Content Number of bits Resolution Effective Range Units 2 Partial message 106 (See Table 5.4.3-13) Table 5.4.3-13 Partial message format of Message Type 25 (Velocity code=0) Repetitions Content Number of bits Resolution Effective Range Units 1 Velocity code（=0） 1 1 0 ― 2 PRN mask no. 6 1 1～51 ― IOD i ** 8 1 0～255 ― o x i 9* 0.125 ±32 m o y i 9* 0.125 ±32 m o z i 9* 0.125 ±32 m o a i,f0 10* 2 -31 ±2 -22 s 1 IODP 2 1 0～3 ― 1 Spare 1 ― ― ― （Velocity code=1） Repetitions Content Number of bits Resolution Effective Range Units 1 Velocity code（=1） 1 1 1 ― 1 PRN mask no. 6 1 1～51 ― IOD i ** 8 1 0～255 ― o x i 11* 0.125 ±128 m o y i 11* 0.125 ±128 m o z i 11* 0.125 ±128 m o a i,f0 11* 2 -31 ±2 -21 s o x ． i 8* 2 -11 ±0.0625 m/s o y ． i 8* 2 -11 ±0.0625 m/s o z ． i 8* 2 -11 ±0.0625 m/s o a i,f1 8* 2 -39 ±2 -32 s/s 1 Epoch time（t i,LT ） 13 16 0～86384 s 1 IODP 2 1 0～3 ― * Parameters so indicated are in two’s complement notation. **The Issue of Data value corresponds to the 8-bit GPS Ephemeris IOD value. IS-QZSS Ver. 1.4 100 An 8-bit Issue of Data value (IOD) is included in the long-term correction data. User receivers must only use navigation messages containing IODC and IODE values that match this number (in the case of IODC, applied to the last 8 bits). If these do not match, it indicates that the GPS navigation message has been updated; however, the receiver should continue to use the old navigation message (for which the IOD matches). If a message type 24 or 25 that matches the new navigation message IOD has been received, the receiver should switch to the new navigation message for positioning. Some time will be required for all user receivers to receive the new navigation message. For this reason, even if the IOD for the GPS navigation message has been updated, the long-term correction data IOD provided by message type 24 and 25 will not be updated for at least two minutes. 5.4.3.3.10 Message Type 26 (Ionospheric Delay & GIVE) Message type 26 provides receivers with augmentation data corresponding to the IGP defined in Table 5.4.3-9. This includes the ionospheric vertical delay (at the L1 frequency) and its accuracy. For more information on the content of the data, see Table 5.4.3-14. The correspondence between GIVEI and σ 2 GIVE is as shown in Table 5.4.3-15. A single message of type 26 provides 15 items of augmentation data for a given IGP. A band number (0 - 9) and a block ID (0 - 13) are also included to specify the corresponding IGP. The band number corresponds to the band numbers in Table 5.4.3-10. Block 0 corresponds to IGP mask numbers 1 - 15 (numbers 1 - 15 of the IGPs for which the IGP mask number is set to "1"). Block 1 corresponds to IGP mask numbers 16 - 30. Augmentation data located at slot numbers that exceed the number of IGPs indicated by the IGP mask data are invalid. The 9-bit ionospheric vertical delay parameter has a resolution of 0.125 m in the effective range of [0, 63.750 m]. A vertical delay of 63.875 m (111111111) indicates "use prohibited”. In other words, a vertical delay exceeding 63.750 m cannot be expressed. Table 5.4.3-14 Message Type 26: Ionospheric Delay Correction Repetitions Content Number of bits Resolution Effective Range Units 1 IGP band ID 4 1 0～9 ― 1 IGP block ID 4 1 0～13 ― 15 Ionospheric vertical delay 9 0.125 0～63.750 m GIVEI i 4 (See Table 5.4.3-15) 1 IODI k 2 1 0～3 ― 1 Spare 7 ― ― ― Table 5.4.3-15 GIVEI Value GIVEI i σ 2 GIVE,i （m 2 ） GIVEI i σ 2 GIVE,i （m 2 ） 0 0.0084 8 0.6735 1 0.0333 9 0.8315 2 0.0749 10 1.1974 3 0.1331 11 1.8709 4 0.2079 12 3.3260 5 0.2994 13 20.7870 6 0.4075 14 187.0826 7 0.5322 15 Not Monitored IS-QZSS Ver. 1.4 101 5.4.3.3.11 Message Type 28 (Clock-ephemeris Covariance) Message type 28 is transmitted to provide the covariance matrix that expresses the correlation between clock and ephemeris error. Using this matrix makes it possible to estimate the degree of degradation of correction data at the receiver position. Table 5.4.3-16 specifies the content and format of message type 28. The PRN mask number is the same as that for message types 24 and 25. Message type 28 includes covariance matrices for two satellites. However, there is only one IODP, and the same PRN mask data are used for both satellites. Table 5.4.3-16 Message Type 28: Clock - Orbit Covariance Repetitions Content Number of bits Resolution Effective Range Units 1 IODP 2 1 0～3 ― 2 PRN mask no. 6 1 1～51 ― Scale factor 3 1 0～7 ― E 1,1 9 1 0～511 ― E 2,2 9 1 0～511 ― E 3,3 9 1 0～511 ― E 4,4 9 1 0～511 ― E 1,2 10* 1 ±512 ― E 1,3 10* 1 ±512 ― E 1,4 10* 1 ±512 ― E 2,3 10* 1 ±512 ― E 2,4 10* 1 ±512 ― E 3,4 10* 1 ±512 ― *: Parameters so indicated shall be in two’s complement notation. 5.4.3.3.12 Message Types 62 (Internal Test Message) and 63 (Null Message) Message type 63 is the Null Message and is always transmitted as a string of 212 zeroes. Message type 62 is used only for internal testing purposes, and its content is not defined. Table 5.4.3-17 Message Type 63 (Null Message) Repetitions Content Number of bits Resolution Effective Range Units 212 All zeroes 1 1 0 ― IS-QZSS Ver. 1.4 102 5.4.3.4 Message Content (SBAS Non-Compatible Message) 5.4.3.4.1 Message Type 52 (TGP Mask) As correction data for the tropospheric delay, Zenith Tropospheric Delay Offset (ZTDO) at the tropospheric grid point (TGP) is transmitted. Message type 52 is used to specify the TGPs that provide ZTDOs. Table 5.4.3-18 specifies the content of message type 52. Message type 52 includes 2 bit TGP issue mask update number （IODT）. This number is incremented each time the TGP Mask is updated. (note: after 3 comes 0) Message type 53 contains the same IODT as message type52. The correction data should be applied with confirmation of the correspondence of IODT between message type 52 and 53 in receivers. All the received correction data could be applied by retaining un-updated mask data until receiving all the messages type 52 and 53 coming after IODT update. The TGPs which provide ZTDOs are specified by using 210 slots in message 52. Table 5.4.3-19 shows the TGP number and its corresponding longitude and latitude. Slot of which position is the same number as TGP number which provides ZTDO is set as ‘1’. Message type 52 is transmitted at least 1 time over a period of 600 seconds. Table 5.4.3-18 Message Type 52：TGP Mask Repetitions Content Number of bits Resolution Effective Range Units 1 ＩＯＤＴ 2 1 0～3 － 210 ＴＧＰ Mask 1 1 0～1 － IS-QZSS Ver. 1.4 103 Table 5.4.3-19 Specification of TGP locations TGP Number East Longitude North Latitude TGP Number East Longitude North Latitude TGP Number East Longitude North Latitude 1 144.5 44.0 36 138.5 36.0 71 145.0 44.0 2 144.5 43.5 37 137.5 36.5 72 145.0 43.5 3 142.5 45.0 38 139.0 35.0 73 145.0 43.0 4 144.0 43.5 39 138.0 35.5 74 143.0 44.5 5 142.5 44.5 40 137.0 36.0 75 144.5 43.0 6 144.0 43.0 41 139.5 33.5 76 143.0 44.0 7 143.0 43.5 42 137.5 35.0 77 142.0 44.5 8 142.5 43.5 43 136.5 35.5 78 143.5 43.0 9 142.0 43.5 44 136.0 35.5 79 143.0 43.0 10 141.5 43.5 45 135.5 35.5 80 142.5 43.0 11 143.0 42.0 46 135.0 35.5 81 142.0 43.0 12 141.5 42.5 47 134.5 35.5 82 141.5 43.0 13 140.5 43.0 48 136.0 34.0 83 141.0 43.0 14 141.5 41.0 49 135.0 34.5 84 141.0 42.0 15 141.0 41.5 50 133.5 35.5 85 140.5 42.0 16 142.0 40.0 51 135.0 34.0 86 141.0 41.0 17 141.0 40.5 52 133.5 35.0 87 140.0 42.0 18 140.0 41.5 53 142.0 26.5 88 141.5 40.0 19 141.5 39.5 54 134.0 34.0 89 140.5 40.5 20 141.0 39.5 55 133.0 34.5 90 140.0 40.5 21 140.5 39.5 56 132.0 35.0 91 141.5 39.0 22 140.0 39.5 57 133.5 33.5 92 141.0 39.0 23 141.0 38.0 58 133.0 33.5 93 140.5 39.0 24 140.5 38.0 59 132.5 33.5 94 140.0 39.0 25 140.0 38.0 60 131.5 34.0 95 141.0 37.5 26 139.5 38.5 61 131.5 33.5 96 140.5 37.5 27 140.5 37.0 62 131.0 33.5 97 139.5 38.0 28 140.0 37.0 63 130.5 33.5 98 139.0 38.0 29 139.0 37.5 64 130.0 33.5 99 140.5 36.5 30 140.5 36.0 65 131.5 32.0 100 139.5 37.0 31 139.5 36.5 66 130.5 32.5 101 138.5 37.5 32 138.5 37.0 67 129.5 33.0 102 140.0 36.0 33 140.0 35.5 68 131.0 31.5 103 139.0 36.5 34 139.0 36.0 69 130.5 31.0 104 138.0 37.0 35 137.0 37.5 70 128.0 26.5 105 139.5 35.5 IS-QZSS Ver. 1.4 104 TGP Number East Longitude North Latitude TGP Number East Longitude North Latitude TGP Number East Longitude North Latitude 106 137.5 37.0 141 145.5 43.5 176 138.0 36.5 107 139.0 35.5 142 144.0 44.0 177 137.0 37.0 108 138.0 36.0 143 142.0 45.5 178 138.5 35.5 109 137.0 36.5 144 143.5 44.0 179 137.5 36.0 110 138.5 35.0 145 142.0 45.0 180 136.5 36.5 111 137.5 35.5 146 143.5 43.5 181 138.0 35.0 112 136.5 36.0 147 142.5 44.0 182 137.0 35.5 113 138.0 34.5 148 142.0 44.0 183 136.0 36.0 114 137.0 35.0 149 143.5 42.5 184 137.5 34.5 115 136.5 35.0 150 143.0 42.5 185 137.0 34.5 116 136.0 35.0 151 142.5 42.5 186 136.5 34.5 117 135.5 35.0 152 142.0 42.5 187 136.0 34.5 118 135.0 35.0 153 141.0 42.5 188 135.5 34.5 119 134.0 35.5 154 140.5 42.5 189 134.5 35.0 120 135.5 34.0 155 140.0 42.5 190 136.0 33.5 121 134.0 35.0 156 141.5 40.5 191 134.5 34.5 122 135.5 33.5 157 140.5 41.0 192 133.0 35.5 123 134.0 34.5 158 142.0 39.5 193 134.5 34.0 124 133.0 35.0 159 141.0 40.0 194 133.5 34.5 125 134.5 33.5 160 140.5 40.0 195 132.5 35.0 126 133.5 34.0 161 140.0 40.0 196 134.0 33.5 127 132.5 34.5 162 141.5 38.5 197 133.0 34.0 128 132.0 34.5 163 141.0 38.5 198 132.5 34.0 129 131.5 34.5 164 140.5 38.5 199 132.0 34.0 130 133.0 33.0 165 140.0 38.5 200 131.0 34.5 131 132.5 33.0 166 141.0 37.0 201 131.0 34.0 132 132.0 33.0 167 140.0 37.5 202 130.5 34.0 133 131.5 33.0 168 139.5 37.5 203 129.5 34.5 134 131.0 33.0 169 138.5 38.0 204 131.5 32.5 135 130.5 33.0 170 140.0 36.5 205 131.0 32.5 136 129.5 33.5 171 139.0 37.0 206 130.0 33.0 137 131.0 32.0 172 140.5 35.5 207 131.5 31.5 138 130.0 32.5 173 139.5 36.0 208 130.5 32.0 139 129.0 33.0 174 138.5 36.5 209 130.5 31.5 140 131.0 30.5 175 140.0 35.0 210 129.0 28.0 IS-QZSS Ver. 1.4 105 5.4.3.4.2 Message Type 53 (Tropospheric Delay Correction) By the message type 53, ZTDO at TGP which is specified by TGP mask data of message type 52 is transmitted to the receivers. Table 5.4.3-20 shows the data content. One message type 53 contains 2bits IODT, 3 bits TGP block ID, and ZTDOs at 34 TGPs. Total number of TGPs which provide ZTDOs is obtained by the mask data of message type 52. Message type 53 with TGP block ID from 0 to an integer n is provided, where the total number of TGPs to provide ZTDOs is larger than 34n and no more than ( ) 34 1 n + . The message type 53 with TGP block ID n contains ZTDOs at from 34 1 n + th to ( ) 34 1 n + th TGPs in the same order as in the effective TGP mask data. ZTDO which is provided 6 bits per 1 point has a resolution of 0.01m in the effective range of [-0.32, 0.30m]. 011111 indicates that ZTDO of corresponding TGP has not been provided. Table 5.4.3-20 Message type 53：Zenith Tropospheric Delay Correction Repetitions Content Number of bits Resolution Effective Range Units 1 ＩＯＤＴ 2 1 0～3 － 1 ＴＧＰ block ＩＤ 3 1 0～6 － 34 ZTDO 6* 0.01 -0.32～0.30 m 1 Reserved 3 － － － *：Parameters shall be in two’s complement notation. 5.4.3.4.3 Message Type 54 (Atmospheric Delay Correction) Content has not been defined yet. 5.4.3.4.4 Message Type 55 (Atmospheric Delay Correction) Content has not been defined yet. 5.4.3.4.5 Message Type 56 (Inter Signal Bias Correction Data) Message type 56 provides the internal signal group delay with respect to the L1C/A signal for the timing at which the multiple signals broadcast by the corresponding GPS or QZSS satellite are actually transmitted from the phase center of the satellite antenna. The PRN mask number has the same meaning as that for message type 25. When multiple signals are used together, the data in this message can be used. Table 5.4.3-21 Message Type 56: Inter Signal Bias Correction Data Repetitions Content Number of bits Resolution Effective Range Units 1 IODP 2 1 0～3 ― 5 PRN mask no. 6 1 1～51 ― ISC L1C_L1CA 9* 0.05 ±12.8 m ISC L2C_L1CA 9* 0.05 ±12.8 m ISC L5_L1CA 9* 0.05 ±12.8 m ISC L1P_L1CA 9* 0.05 ±12.8 m *: Parameters so indicated shall be in two’s complement notation. IS-QZSS Ver. 1.4 106 5.4.3.4.6 Message Type 57 (Orbit Data) Content has not been defined yet. 5.4.3.4.7 Message Type 58 (QZS Ephemeris) Message type 58 is transmitted to provide QZS Ephemeris data. The satellite position is provided in the form of coordinates in the Japan satellite navigation Geodetic System (JGS) orthogonal coordinate system in reference epoch t 0 , Q . Table 5.4.3-22 QZS Ephemeris Data Item Number of bits Range Resolution Notes ｔ 0,Q 8 0－10740s 60s Epoch time URA 4 0-15 － Positioning accuracy indicator Q X 26* ±42949.673 km 1.28 m X coordinate Q Y 26* ±42949.673 km 1.28 m Y coordinate Q Z 26* ±42949.673 km 1.28 m Z coordinate Q X  24* ±4194.304 m/s 0.5 mm/s Velocity Q Y  24* ±4194.304 m/s 0.5 mm/s Velocity Q Z  24* ±4194.304 m/s 0.5 mm/s Velocity Q X   5* ±32 μm/s 2 μm/s Acceleration Q Y   5* ±32 μm/s 2 μm/s Acceleration Q Z   5* ±32 μm/s 2 μm/s Acceleration a Qf0 22* ±1.953 ms 2 -30 s Clock correction a Qf1 13* ±3.725 ns/s 2 -40 s/s Clock correction Total 212 *: Parameters so indicated shall be in two’s complement notation. 5.4.3.4.8 Message Type 59 (QZSS Almanac Data) Content has not been defined yet. 5.4.3.4.9 Message Type 60 ((Regional information/maintenance schedule)) Content has not been defined yet. 5.4.3.5 L1-SAIF+ Message L1-SAIF+ Message is the message that Satellite Positioning Research and Application Center (SPAC) will transmit for the applications demonstration. For L1-SAIF+ Message, the message type 40 - 51 is defined as L1-SAIF+ Unique Message in addition to SBAS compatible message in Section 5.4.3.3, SBAS non- compatible message in Section 5.4.3.4. The detailed information are referenced in Interface Specification (Applicable Documents (6)) to be established by SPAC. IS-QZSS Ver. 1.4 107 5.5 L2C signal 5.5.1 RF characteristics 5.5.1.1 Signal configuration In accordance with Section 5.1. 5.5.1.2 Carrier wave properties In accordance with Section 5.1. 5.5.1.3 Code properties 5.5.1.3.1 Code attributes Same as sections 3.2.1.4, 3.2.1.5 and 3.3.2.4 of Applicable Document (1). However, the PRN code number is as described in Section 5.1.1.11.1 of this document. 5.5.1.3.2 Non-standard code In the event of a problem with QZSS, a non-standard code (NSC) is transmitted. This is done to protect users by ensuring that they do not receive or use erroneous navigation data. 5.5.2 Message 5.5.2.1 Message configuration Each message of the L2C signal (D L2C ) comprises 300 bits: 276 bits of data and 24 parity check bits. Each message is broadcast for 12 seconds. This message configuration is the same as in Applicable Document (1). 5.5.2.1.1 Preamble The 8-bit preamble added to the beginning of each frame is the same as in Section 30.3.3 of Applicable Document (1). 5.5.2.1.2 PRN number The 6-bit PRN number added after the preamble in each frame is the last 6 bits of the PRN number for the QZS transmitting the corresponding message. 5.5.2.1.3 Message type ID The 6-bit message type ID added after the PRN number in each frame signifies the data contained in that frame. Table 5.5.2-1 specifies the message content for each of the individual message types. For more information, see Section 5.5.2.2. The different types of messages are transmitted at intervals not to exceed the Maximum Broadcast Periods specified in Table 5.5.2-2. QZSs may transmit the same message type with different timing. IS-QZSS Ver. 1.4 108 Table 5.5.2-1 Definitions of message types for Navigational Message D L2C Message type Message content Notes 10 Health, URA, Ephemeris 1 11 Ephemeris 2 30, 46 SV clock, ionospheric parameter, ISC When value is 46: Rebroadcast of ionospheric parameters broadcasted by GPS, however ISC broadcasted by GPS is not rebroadcasted by QZSS 31, 47 * SV clock, reduced Almanac When value is 47: Rebroadcast of GPS reduced Almanac 32 SV clock, EOP (Earth Orientation Parameter) 33, 49 SV clock, UTC parameter When value is 49: Rebroadcast of GPS UTC parameters 34 SV clock, performance enhancement data Transmitted as needed 35, 51 SV clock, GGTO (GPS GNSS Time Offset ) When value is 51: Rebroadcast of GGTO broadcasted by GPS 37, 53 SV clock, Midi Almanac When value is 53: Rebroadcast of GPS Midi Almanac 12 * , 28 Reduced Almanac When value is 28: Rebroadcast of GPS reduced Almanac 13 SV clock performance enhancement data Transmitted as needed 14 Ephemeris performance enhancement data Transmitted as needed 15 Text Transmitted as needed * QZS-1 does not be broadcasting the data of Type 12 and 47 because the contents of them are same with those of type 31 and 28. Broadcasting the data of type 12 and 47 after "Phase Two" is under study Table 5.5.2-2 Maximum Transmit periods for Navigational Message D L2C Message Data Message Type Maximum broadcast Period Notes Ephemeris 10,11 48 seconds SV clock 30-35, 37, 46, 47, 49, 51, 53 48seconds ISC, ionospheric parameter 30 288 seconds ISC, ionospheric parameter (GPS rebroadcasting) 46 * Reduced Almanac of QZSS 31 or 12 20 minutes All necessary SV data must be transmitted Reduced Almanac of GPS (GPS rebroadcasting) 47 or 28 * All necessary SV data must be transmitted Midi Almanac of QZSS 37 120 minutes All necessary SV data must be transmitted Midi Almanac of GPS (GPS rebroadcasting) 53 * All necessary SV data must be transmitted EOP 32 30 minutes UTC parameters 33 288 seconds UTC parameters (GPS rebroadcasting) 49 * DC data 34 or 13 & 14 30 minutes (*) Only when performance enhancement data are effective GGTO (GPS-QZSS Time Offset) 35 288 seconds GGTO (GPS-Galileo Time Offset) 51 * Text 15 As needed * We will not define the maximum transmit period for GPS rebroadcasting parameters and GPS DC data. IS-QZSS Ver. 1.4 109 5.5.2.1.4 TOW count The 17-bit TOW (Time of Week) count that follows the message type ID in each frame indicates the time at the beginning of the next frame, which is six times that value. This is the same as in Applicable Document (1). 5.5.2.1.5 "Alert" flag The 1-bit "Alert" flag that follows the TOW count in each frame is in accordance with Section 5.1.2.1.3. 5.5.2.1.6 FEC and parity algorithm The CNAV will be encoded with FEC. The algorithm for encoding is the same as in Section 3.3.3.1.1 of Applicable Document (1). The 24-bit parity code added after the 300-bit frame. The parity algorithm is the same as in Section 30.3.5 of Applicable Document (1). 5.5.2.2 Message content With the exception of the list in Section 8.1.2, the content of the message is the same as in Applicable Document (1). 5.5.2.2.1 Ephemeris data and health for message types 10 and 11 5.5.2.2.1.1 Content of Ephemeris data and health for message types 10 and 11 Message types 10 and 11 include the Ephemeris data (such as that shown in Table 5.5.2-3) for the corresponding satellite. The general content is the same as in Section 30.3.3.1.1 of Applicable Document (1). IS-QZSS Ver. 1.4 110 Table 5.5.2-3 Definition of Ephemeris parameters for Navigational Message D L2C Parameter Definition Difference from GPS definition 10 WN n Week Number 10 L1/L2/L5 Health L1, L2 and L5 signal health 10 t op Data predict time of week (seconds into week) 10 URA oe index Ephemeris accuracy index 10 11 t oe Ephemeris epoch (seconds into week) 10 AA Difference from semi major axis at t oe In the case of QZS, indicates difference with 42,164,200 [m] In the case of GPS, indicates difference with 26,559,710 [m] 10 A  Change rate in semi major axis 10 An 0 Difference from mean motion calculation at t oe 10 0 n A Change rate from mean motion calculation 10 M 0-n Mean anomaly at t oe 10 e n Eccentricity 10 ω n Argument of perigee 11 Ω 0-n Longitude of ascending node at the beginning of the week 11 I 0-n Orbit inclination at t oe 11 AΩ ． Rate of Right ascension of ascending node (RAAN) difference from reference value *1 11 i o-n -DOT Change rate in orbit inclination 11 C is-n Amplitude of the sine harmonic correction term to the angle of inclination 11 C iｃ-n Amplitude of the cosine harmonic correction term to the angle of inclination 11 C ｒs-n Amplitude of the sine correction term to the orbit radius 11 C ｒc-n Amplitude of the cosine correction term to the orbit radius 11 C us-n Amplitude of the sine harmonic correction term to the argument of latitude 11 C uc-n Amplitude of the cosine harmonic correction term to the argument of latitude * Relative to ] cond circles/se - semi [ 10 6 . 2 9 ÷ × ÷ = O REF  (same value with GPS). (1) Transmission Week Number Bits 39 - 51 in message type 10 constitute a binary expression for the 8192 remainder of the current GPS Week Number. This is the same as in Section 30.3.3.1.1.1 of Applicable Document (1). IS-QZSS Ver. 1.4 111 (2) Signal health (L1/L2/L5) The three single bits from bit 52 to bit 54 in message type 10 indicate the health of the L1, L2 and L5 signals, respectively, transmitted by the corresponding satellite. The value for the L1 signal is "1" in the event that there is a problem with one or more of the L1C/A, L1-SAIF or L1C signals. 0 No problems with signal 1 Problem with signal exists or signal cannot be used These bit indices are compared to the monitoring results at the present time for the corresponding satellite. The details are in accordance with Section 5.1.2.1.3. Health data are also present in message types 12, 31 and 37. The data in message type 10 are uploaded at a different time, so the data may differ from that for the transmission satellites of other messages and other satellite data. (3) Data Predict Time of week: op t Bits 55-65 in message type 10 indicate the data predict time of week ( op t ). The op t term provides the epoch time of week of the state estimate utilized for the prediction of satellite ephemeris parameters. This is the same as in Section 30.3.3.1.3 of Applicable Document (1). (4) Accuracy indicator for Ephemeris data: oe URA index Bits 66-70 in message type 10 indicate the SIS accuracy indicator for Ephemeris data. For more information, see Section 5.1.2.1.3.2. (5) Ephemeris data epoch: oe t Bits 71 - 81 in message type 10 and bits 39 - 49 in message type 11 indicate the epoch for Ephemeris data. This is the same as in Figure 30-1 and Table 30-I of Applicable Document (1). (6) Ephemeris data After the URA oe index in message type 10, the Ephemeris data (shown in Table 5.5.2-3) for the corresponding satellite are transmitted. In the data, ΔA represents the value of the Semi-Major Axis in the context of t oe ( ( ) oe t A ) minus 42,164,200 [m]: ( ) ( ) ] [ 200 , 164 , 42 m t A t A oe oe ÷ = A Other values are the same as in Figure 30-1 and Table 30-I of Applicable Document (1). 5.5.2.2.1.2 Characteristics of Ephemeris Data Parameters for Message Types 10 and 11 With the exception of those items shown in the previous section (5.5.2.2.1.1), the parameter characteristics for message types 10 and 11 (number of bits, LSB scale factor, data range and units) are the same as those shown in Table 30-I of Applicable Document (1). Bit allocation for message types 10 and 11 is the same as in Figures 30-1 and 30-2 of Applicable Document (1). However, Integrity Status Flag and L2C Phasing Flag were added in Figure 30-1 of Applicable Document (1), QZS-1 did not adopt. After "Phase Two", adoption of the Integrity Status flag is under study, but L2C Phasing Flag will not be adopted. 5.5.2.2.1.3 Message Types 10 and 11: User Algorithms for Satellite Positioning In accordance with Section 6.3.5. IS-QZSS Ver. 1.4 112 5.5.2.2.2 Message types 30 through 35, 37, 46, 47, 49, 51 and 53: SV Clock Correction Parameters 5.5.2.2.2.1 Message types 30 through 35, 37, 46, 47, 49, 51 and 53: Content of SV Clock Parameters Message types 30, 31, 32, 33, 34, 35 37, 46, 47, 49, 51 and 53 all contain SV clock parameters for the corresponding satellite such as those shown in Table 5.5.2-4. For an overview, see Section 30.3.3.2.1 of Applicable Document (1). Table 5.5.2-4 Definition of SV clock parameters for Navigational Message D L2C Parameter Definition Difference from GPS definition ｔ oc SV clock parameter epoch (seconds into week) URA OC index SV clock accuracy index URA OC1 index SV clock accuracy change index URA OC2 index SV clock accuracy change rate index a f0-n SV clock bias correction term a f1-n SV clock drift correction term a f2-n SV clock drift rate correction term (1) Data predict time of accuracy indicator for SV clock parameters (t op ) Bits 39 - 49 indicate the data predict time of week (t op ) for the accuracy indicator for the SV clock parameters. (2) SV clock parameter accuracy indicator (URA oc index) Bits 50 - 60 include the parameter needed to determine the SIS accuracy of the SV clock parameters (URA oc ). Details are in accordance with Section 5.1.2.1.3.2. (3) SV clock parameter epoch (t oc ) Bits 61 - 71 constitute the SV clock parameter epoch t oc . (4) SV clock parameter The SV clock parameter for the corresponding satellite, shown in Table 5.5.2-4, will be transmitted. The user algorithm is the same as in Section 20.3.3.3.3.1 of Applicable Document (1). However, certain parts of the definition are different; for more information, see Section 6.3.2. 5.5.2.2.2.2 Message types 30 through 35, 37, 46, 47, 49, 51 and 53: Characteristics of SV Clock Parameters With the exception of those items shown in the previous section (Section 5.5.2.2.2.1), the parameter characteristics for message types 30, 31, 32, 33, 34, 35, 37, 46, 47, 49, 51 and 53 (clock correction parameter number of bits, LSB scale factor, data range and units) are the same as those shown in Table 30-III of Applicable Document (1). IS-QZSS Ver. 1.4 113 5.5.2.2.2.3 Message types 30 through 35, 37, 46, 47, 49, 51 and 53: User Algorithm for SV Clock Correction Data (1) Calculation of Accuracy for SV Clock Parameter: URA oc calculation. The algorithm used to determine the detailed user positioning accuracy (URA oc ) expressed by URA oc index is the same as in Section 30.3.3.2.4 of Applicable Document (1). For more information about how to use URA oc , see Section 3.1.2.1.3. For more information about the content of URA oc , see Section 5.1.2.1.3. Note: Refer to the above Applicable Document (1), URA oc is calculated in quadratic equation of the time. The coefficient of the linear term and that of quadratic term become larger than 0 by definition. The coefficient of the linear term would become larger than 1.7578 m after 3600 seconds from the t op because t op is updated every 3600 seconds for QZSS. (2) Calculation of SV clock offset using SV clock parameters As this is an estimate by the Control Segment by means of the L1C/A signal and the L2C signal code measurement, there are additions to the SV clock correction algorithm for one-signal users and 2-signal (L1C/A and L2C) users. See Section 6.3.2 for details. 5.5.2.2.3 Message Type 30, 46: Ionospheric Parameter and Group Delay Correction Parameter In addition to the SV clock parameters (Section 5.5.2.2.2), message type 30 includes the ionospheric parameters like those shown in Table 5.5.2-5 and the internal signal group delay correction parameters shown in Table 5.5.2-6. For more information regarding the content of these parameters, see Section 30.3.3.3.1 of Applicable Document (1). Ionospheric parameters in Message type 46 are rebroadcast of parameters broadcasted by GPS. Since Group Delay Correction parameters broadcasted by GPS is NOT rebroadcasted by QZSS, bits 128 to 192 in message type 46 can NOT be used. Table 5.5.2-5 Definition of ionospheric parameters for Navigational Message D L2C Parameter Definition Difference from GPS definition α 0 Ionospheric parameter α 0 for Klobuchar model Coefficient optimized for Japan & environs α 1 Ionospheric parameter α 1 for Klobuchar model Coefficient optimized for Japan & environs α 2 Ionospheric parameter α 2 for Klobuchar model Coefficient optimized for Japan & environs α 3 Ionospheric parameter α 3 for Klobuchar model Coefficient optimized for Japan & environs β 0 Ionospheric parameter β 0 for Klobuchar model Coefficient optimized for Japan & environs β 1 Ionospheric parameter β 1 for Klobuchar model Coefficient optimized for Japan & environs β 2 Ionospheric parameter β 2 for Klobuchar model Coefficient optimized for Japan & environs β 3 Ionospheric parameter β 3 for Klobuchar model Coefficient optimized for Japan & environs IS-QZSS Ver. 1.4 114 Table 5.5.2-6 Group Delay Correction Parameters (T GD , ISC) for Navigational Message D L2C Parameter Definition Difference from GPS definition T GD LC QZSS .and.L1C/A group delay LC GPS and L1P(Y) group delay for GPS ISC L1C/A N/A (Broadcasting value is 0.0) L1P(Y) - L1C/A for GPS ISC L2C L1C/A – L2C group delay L1P(Y) – L2C for GPS ISC L5I5 L1C/A - L5I5 group delay L1P(Y) – L5I5 for GPS ISC I5Q5 L1C/A - L5Q5 group delay L1P(Y) – L5Q5 for GPS LC QZSS ： LC QZSS is the ionospheric error free linear combination of the L1C/A and L2C signals for QZSS LC GPS ： LC GPS is the ionospheric error free linear combination of the L1P(Y) and L2P(Y) signals for GPS (1) Ionospheric parameters This section provides the ionospheric parameters used by one-signal users (who use only the L1, L2 or L5 signal) when they use an ionospheric model to calculate the ionospheric delay. These parameters are specialized to fit the geographic area shown in Figure 4.1.5-1. User algorithms for one-signal users are in accordance with Sections 6.3.4 and 6.3.8. These parameters use data from the past 24 hours (Maximum) and are updated at least once per day except “ionospheric maximum periods”. The number of bits, scale factor, range and units are the same as in Section 20.3.3.5.2.5 and Table 20-X of Applicable Document (1). (2) Estimating the L1-L2 group delay error Group delay error terms T GD , ISC L1C/A and ISC L2C for users of only one signal (L1C/A, L1C, L2C or L5) and L1/L2 users are contained in bits 128 - 166 of message type 30. Of these, ISC L1C/A has a value of zero. Table 30-IV of Applicable Document (1) shows the number of bits, scale factor, range and units. "Bit string "1000000000000" indicates that the group delay value cannot be used. The relevant algorithms are shown in Sections 6.3.3 and 6.3.4. 5.5.2.2.4 Message Types 31, 12, 37, 47, 28 and 53: Almanac Data QZS Almanac data are provided by message types 31, 12 and 37. The Reduced Almanac is provided by message type 31 or 12, and the Midi Almanac is provided by message type 37. The PRN number for these message types indicates the last 6 bits of the QZS PRN. Almanac data for other satellite positioning systems are provided by message types 47, 28 and 53. The Reduced Almanac is provided by message type 47 or 28, and the Midi Almanac is provided by message type 53. Of the PRN numbers for these message types, numbers 1-32 are for GPS satellites. The Reduced Almanac for satellites is broadcast by a single satellite in a shorter interval than the Midi Almanac. IS-QZSS Ver. 1.4 115 Table 5.5.2-7 Definition of Midi Almanac parameters for Navigational Message D L2C Parameter Definition Difference from GPS definition WN a-n GPS Week Number at the time of Midi Almanac generation t oa Midi Almanac epoch (second in week) PRN no. When the message type number is 37, it indicates that this value is for a QZS satellite and constitutes the offset value from the PRN number of 193 for the target satellite. When the message type number is 53, it indicates that this value is the PRN value for a GPS satellite. L1/L2/L5 Health L1, L2 and L5 signal health E Eccentricity (offset from the nominal QZS eccentricity of 0.06) Only values up to 0.03 can be expressed in the case of GPS i o Offset from the reference QZS orbit inclination (0.25 [semi-circles]) （Offset from 0.25 [semi-circle]=45 [deg]） In the case of GPS, the reference inclination is 0.3 [semi-circles], which represents 54 [deg]. O  Change rate in right ascension of ascending node (RAAN) A Square root of Semi-Major Axis 0 O Longitude of ascending node at the beginning of the week e Argument of perigee M 0 Mean anomaly a f0 Bias term for SV clock a f1 Drift term for SV clock Table 5.5.2-8 Definition of Reduced Almanac parameters for Navigational Message D L2C Parameter Definition Difference from GPS definition WN a-n GPS Week Number at the time of Reduced Almanac generation t oa Reduced Almanac epoch (second in week) PRN no. When the message type number is 31 or 12, it indicates that this value is for a QZS satellite and constitutes the offset value from the PRN number of 193 for the target satellite. When the message type number is 47 or 28, it indicates that this value is the PRN value for a GPS satellite δA Offset from the nominal QZS Semi-Major Axis of 42,164,200 [m] In the case of GPS, indicates the offset from 26,559,710 [m] Ω 0 Longitude of ascending node at the beginning of the week Φ 0 Argument of latitude (= M 0 + w) Based on the assumption that ω= 270 [deg] L1/L2/L5 Health L1, L2 and L5 signal health (e) Implicit eccentricity (0.075 in the case of QZS) (precondition for above parameter) 0 in the case of GPS (δi) Fixed at -0.0111 [semi-circles], the offset from the reference QZS orbit inclination of 0.25 [semi-circles] (precondition for above parameter) In the case of GPS, fixed at +0.0056 [semi-circles], the offset from 0.3 [semi-circles] (ω) Implicit Argument of Perigee (270 [deg] in QZS-1） （Precondition for above parameters） 0 [deg] in case of GPS IS-QZSS Ver. 1.4 116 5.5.2.2.4.1 Almanac Reference Week Number Bits 39 - 51 in message types 12 and 28 and bits 128 - 140 in message types 31and 37 (and 47 and 53) indicate the Week Number (WN a-n ) that serves as a reference for the Almanac reference time (t oa ) (see Section 20.3.3.5.2.2 of Applicable Document (1)). WN a-n is made up of 13 bits and is expressed by the modulo-8192 GPS Week Number (see Section 6.3.6) that serves as a reference for t oa . 5.5.2.2.4.2 Almanac reference time Bits 52-59 in message type 12 (and 28) and bits 141-148 in message types 31 and 37 (and also 47 and 53) indicate the Almanac reference time (t oa ).See Section 20.3.3.5.2.2 of Applicable Document (1). 5.5.2.2.4.3 Satellite PRN number The first 6 bits in the 31-bit Reduced Almanac included in message types 31 and 12 (and also 47 and 28) constitute the corresponding satellite’s PRN. In the case of message types 31 and 12, the PRN constitutes the last 6 bits of the QZS PRN. In the case of message types 47 and 28, the PRN number 1 to 32 is a GPS PRN number. If the Almanac data is not effective, the value of the PRN Number is set to “111111” as in Applicable Document (3). In this event, the remainder of the rest of 22 bits in the data block shall be filler bits, i.e., alternating ones and zeros beginning with one, and the 3-Bit-Health is set to “111” (cf. Section 5.5.2.2.4.4). There is a PRN in bits 149-154 of the Midi Almanac included in message type 37 (and 53). In the case of message type 37, the PRN constitutes the last 6 bits of the QZS PRN. In the case of message type 53, the PRN is a GPS PRN. 5.5.2.2.4.4 Signal health (L1/L2/L5) The three 1-Bit -Health indicators – bits 155, 156 and 157 in message type 37 (and 53) and bits 29, 30 and 31 in the Reduced Almanac in message types 31 and 12 (and also 47 and 28) relate to the L1, L2 and L5 signals for the satellite corresponding to the PRN number. Their meaning is covered in Section 5.1.2.1.3. 5.5.2.2.4.5 Midi Almanac data content Message type 37 (and 53) provides the Almanac for the satellite with the PRN number shown in the message. The number of bits, scale factor, range and units are the same as in Table 30-V of Applicable Document (1). However, the QZS eccentricity and inclination differs from that of GPS and is provided relative to the reference values as noted below. (1) Eccentricity (a) In the case of QZSS: nav e 0.06 + = a e (b) In the case of GPS: nav e 0.00 + = a e Reference in accordance with Applicable Document (1) a e : Actual eccentricity value nav e : Eccentricity value included in navigation message IS-QZSS Ver. 1.4 117 (2) Inclination (a) In the case of QZSS: ] [ 25 . 0 circle semi i i a ÷ + = o (b) In the case of GPS: ] [ 3 . 0 circle semi i i a ÷ + = o Reference in accordance with Applicable Document (1) i a : Actual inclination value δi: Inclination value included in navigation message For the user algorithm, see Section 6.3.6. The Midi Almanac data for the QZS are updated approximately once every 3.5 days. The velocity calculated by the Midi Almanac data is accurate within 30m/s. 5.5.2.2.4.6 Content of Reduced Almanac Data Message type 31 and 12 (and also 47 and 28) contain multiple reduced Almanac data values. Semi major axis and inclination are provided relative to reference values as shown below. (1) Semi-Major Axis (a) For QZSS: A [m] 42,164,200 A o + = (b) For GPS: A [m] 26,559,710 A o + = Reference in accordance with Applicable Document (1) (2) Eccentricity (a) For QZSS: 0.075 = e (b) For GPS: 0.0 = e Reference in accordance with Applicable Document (1) (3) Orbit Angle of Elevation (a) For QZSS: [deg] 43 = i (b) For GPS: [deg] 55 = i Reference in accordance with Applicable Document (1) (4) Time change rate for right ascension of ascending node (RAAN) (a) For QZSS: ] conds circles/se semi [ 10 7 8. 10 ÷ × ÷ = O ÷  (b) For GPS: ] conds circles/se semi [ 10 6 . 2 9 ÷ × ÷ = O ÷  Reference in accordance with Applicable Document (1) (5) Implicit Argument of Perigee (a) For QZSS: [deg] 270 = e (b) For GPS: [deg] 0 = e The number of bits, LSB scale factor, range and units are the same as in Table 30-VI of Applicable Document (1). For the user algorithm, see Section 6.3.6. The Reduced Almanac data for the QZS are updated approximately every 3.5 days. The velocity calculated by the Reduced Almanac data is accurate within 350 m/s. IS-QZSS Ver. 1.4 118 5.5.2.2.5 Message type 32: Earth orientation parameter (EOP) The Earth rotation parameter is included in message type 32. The definition, number of bits, scale factor, range, units, LSB, user algorithm, etc., for this parameter are all the same as table 30-VII in Applicable Document (1). 5.5.2.2.6 Message type 33, 49: UTC Parameters The UTC parameters are included in message type 33 (and 49). When the Message Type = 33, the UTC parameters transmitted by the QZS is needed to link GPS time to UTC (NICT). When the Message Type = 49, those are gathered by receiving GPS signals at QZS Monitor Stations and re-broadcasted to link GPS time to UTC (USNO). The number of bits, scale factor, range, units, LSB, user algorithm, etc., for this parameter are all the same as Section 30.3.3.6 and Table 30-IX in Applicable Document (1). 5.5.2.2.7 Message Type 34, 13, 14: Differential Correction Data (DC Data) Differential correction data (DC data) are included in message types 34, 13 and 14. These parameters provide users with correction terms for SV clock parameters and Ephemeris data transmitted by other satellites. DC data is divided into packets that comprise a 34-bit SV clock error correction (CDC) parameter and a 92-bit Ephemeris error correction (EDC) parameter. CDC and EDC data are paired, and users must use the CDC and EDC pair corresponding to the same D op t ÷ and t OD . Message type 34 includes the CDC and EDC for one satellite. Message type 13 includes the CDC data for six satellites, while message type 14 includes the EDC data for two satellites. A DC Type indicator "0" indicates that the corresponding correction parameters should be applied to CNAV data, while "1" indicates that the corrections should be applied to the navigation message for the L1C/A signal. The content of the data packets is the same as Section 30.3.3.7 in Applicable Document (1). The content is shown in Table 5.5.2-9. The bit definition, number of bits, scale factor and unit for DC data are the same as Table 30-XI in Applicable Document (1). If the DC data is not effective, the value of the PRN Number is set to “11111111” as Section 30.3.3.7.2.3 in Applicable Document (1). In this case, DC type indicator is set to “0”. IS-QZSS Ver. 1.4 119 Table 5.5.2-9 Definition of parameters for DC data for Navigational Message D L2C Parameter Definition Difference from GPS definition ｔ op-D Prediction time of week for DC data (second in week) t OD Reference time of week for DC data (second in week) DC Type indicator 1: For D LIC/A message 0: For D L2C message PRN no. PRN no. (range 0 - 255) for satellite for which performance enhancement data will be applied 1 - 32 if target is GPS; 193 - 197 if target is QZSS f0 a o Bias term for SV clock f1 a o Drift correction term for SV clock UDRA index User Differential Range Accuracy (UDRA) index o A o correction term for Ephemeris parameter | A | correction term for Ephemeris parameter ¸ A ¸ correction term for Ephemeris parameter i A Correction term for orbit inclination AO Correction term for right ascension of ascending node (RAAN) A A Correction term for Semi-Major Axis UD ． RA index UDRA rate index 5.5.2.2.7.1 Differential Correction (DC) data DC data include the following. For more information regarding the use of DC data, see Section 3.1.2.1.3.4. (1) Time of DC data estimation ( D op t ÷ ) “ D op t ÷ ” indicates the time (seconds into week) at which DC data were estimated. This value is the same as Section 30.3.3.7.2.1 in Applicable Document (1). (2) DC data epoch ( OD t ) “ OD t ” indicates the epoch (seconds into week) for DC data. This value is the same as Section 30.3.3.7.2.2 in Applicable Document (1). (3) Satellite PRN identification The 8-bit PRN specifies the satellite for which the corresponding DC data set is to be used. When PRN is 1-32, it indicates GPS; when PRN is 193-197, it indicates QZSS. If the bit values are all set to "1", then there are no DC data in the data block. This is the same as Section 30.3.3.7.2.3 in Applicable Document (1) in the sense that the remaining data consist of alternating bit values of "1" and "0". (4) Use of CDC data Same as Section 30.3.3.7 in Applicable Document (1). For more information, see Section 6.3.9.2. IS-QZSS Ver. 1.4 120 (5) Use of EDC data Same as Section 30.3.3.7 in Applicable Document (1). For more information, see Section 6.3.9.2. 5.5.2.2.7.2 DC Data Accuracy The User Differential Range Accuracy, UDRA op-D , and its time derivative, UD ． RA, indicate the positioning accuracy after DC data have been applied to the SV clock parameter and Ephemeris data. The bit definition, number of bits, etc., and user algorithm are the same as Figure 30-16 and Section 30.3.3.7.5 in Applicable Document (1). For more information regarding the use of UDRA op-D and UD ． RA, see Section 3.1.2.1.3.5. 5.5.2.2.8 Message type 35, 51: GPS/GNSS time offset: GGTO Message type 35 (and 51) is the parameter used to adjust GPS time to match other GNSS times. The bit definition, number of bits, scale factor (LSB), range and units are all the same as Figure 30-8 and Table 30-XI in Applicable Document (1). The effective period for GPS GNSS Time Offset (GGTO) is at least 24 hours. Table 5.5.2-10 Definition of GPS GNSS Time Offset (GGTO) parameters for Navigational Message D L2C Parameter Definition Difference from GPS definition t GGTO Seconds into GGTO reference week WN GGTO GGTO reference Week Number GNSS ID See Section 5.5.2.2.8.1 A 0GGTO GPST bias term associated with other GNSS system time A 1GGTO GPST drift term associated with other GNSS system time A 2GGTO GPST drift rate term associated with other GNSS system time 5.5.2.2.8.1 GNSS - ID Bits 155-157 in message type 35 define the other satellite positioning systems to which data offsets with respect to GPS are applied. The definitions of these three bits are as follows. 000: Data cannot be used 001: Galileo 010: GLONASS 011: QZSS 100 - 111: Spare 5.5.2.2.8.2 GPS/GNSS Time Offset The algorithm used to determine GPS GNSS Time Offset (GGTO) is the same as in Applicable Document (1). However, the QZS SV clock parameter already uses GPST as the reference, so the time offset value for GPS and QZSS (GQTO) is zero. 5.5.2.2.9 Message Types 15: Text Messages Text messages are transmitted using the 29 8-bit ASCII characters in message type 15. The bit definition, number of bits, etc., is the same as Figure 30-14 in Applicable Document (1). IS-QZSS Ver. 1.4 121 5.6 L5 signal 5.6.1 RF characteristics 5.6.1.1 Signal configuration In accordance with Section 5.1. Inner FEC ½ Coder (7 Convolution) 10-symbol NH Code (1ksps) Outer FEC Coder (CRC 24) CNAV (100sps) L5I L5 Navigation Message (276bits) 300bits/6s 600bits/6s 10bits-Length/10ms 20-symbol NH Code (1ksps) 20bits-Length/20ms L5Q PRN as Ranging Code Ranging Code (10.23Mcps) 10230chips-Length/1ms XI XQ Figure 5.6.1-1 L5 Signal Structure 5.6.1.2 Carrier wave properties In accordance with Section 5.1. 5.6.1.3 Code properties 5.6.1.3.1 Code attributes Same as sections 3.2.1, 3.3.2 and 6.3.4 of Applicable Document (2). However, the PRN code number is as described in Section 5.1.1.11.1 of this document. 5.6.1.3.2 Non-standard code In the event of a problem with QZSS, a non-standard code (NSC) is transmitted. This is done to protect users by ensuring that they do not receive or use erroneous navigation data. 5.6.2 Message 5.6.2.1 Message configuration Each message of the L5 signal (D L5 ) comprises 300 bits: 276 bits of data and 24 parity check bits. Each message is broadcast for 6 seconds. This message configuration is the same as Section 20.3.2 in Applicable Document (2). IS-QZSS Ver. 1.4 122 5.6.2.1.1 Preamble The 8-bit preamble added to the beginning of each frame is the same as Section 20.3.3 in Applicable Document (2). 5.6.2.1.2 PRN number The 6-bit PRN number added after the preamble in each frame is the last 6 bits of the PRN number for the QZS transmitting the corresponding message. 5.6.2.1.3 Message type ID The 6-bit message type ID added after the PRN number in each frame signifies the data contained in that frame. Table 5.6.2-1 specifies the message content for each of the individual message types. For more information, see Section 5.6.2.2. The different types of messages are transmitted at intervals not to exceed the Maximum Broadcast Periods specified in Table 5.6.2-2. QZSs may transmit the same message type with different timing. Table 5.6.2-1 Definitions of message types for Navigational Message D L5 Message type Message content Notes 10 Health, URA, Ephemeris 1 11 Ephemeris 2 30, 46 SV clock, ionospheric parameter, ISC When value is 46: Rebroadcast of ionospheric parameters broadcasted by GPS, however ISC broadcasted by GPS is not rebroadcasted by QZSS 31, 47 * SV clock, Reduced Almanac When value is 47: Rebroadcast of GPS reduced Almanac 32 SV clock, EOP (Earth Orientation Parameter) 33, 49 SV clock, UTC parameter When value is 49: Rebroadcast of GPS UTC parameters 34 SV clock, performance enhancement data Transmitted as needed 35, 51 SV clock, GGTO (GPS GNSS Time Offset ) When value is 51: Rebroadcast of GGTO broadcasted by GPS 37, 53 SV clock, Midi Almanac When value is 53: Rebroadcast of GPS Midi Almanac 12 * , 28 Reduced Almanac When value is 28: Rebroadcast of GPS reduced Almanac 13 SV clock performance enhancement data Transmitted as needed 14 Ephemeris performance enhancement data Transmitted as needed 15 Text Transmitted as needed * QZS-1 does not be broadcasting the data of Type 12 and 47 because the contents of them are same with those of type 31 and 28. Broadcasting the data of type 12 and 47 after "Phase Two" is under study IS-QZSS Ver. 1.4 123 Table 5.6.2-2 Maximum Transmit periods for Navigational Message D L5 Message Data Message Type Maximum broadcast Period Notes Ephemeris 10,11 24 seconds SV clock 30-35, 37, 46, 47, 49, 51, 53 24 seconds ISC, ionospheric parameter 30 144 seconds ISC, ionospheric parameter (GPS rebroadcasting) 46 * Reduced Almanac of QZSS 31 or 12 10 minutes All necessary SV data must be transmitted Reduced Almanac of GPS (GPS rebroadcasting) 47 or 28 * All necessary SV data must be transmitted Midi Almanac of QZSS 37 60 minutes All necessary SV data must be transmitted Midi Almanac of GPS (GPS rebroadcasting) 53 * All necessary SV data must be transmitted EOP 32 15 minutes UTC parameters 33 144 seconds UTC parameters (GPS rebroadcasting) 49 * DC data 34 or 13 & 14 15 minutes (*) Only when performance enhancement data are effective GGTO (GPS-QZSS Time Offset) 35 144 seconds GGTO (GPS-Galileo Time Offset) 51 * Text 15 As needed * We will not define the maximum transmit period for GPS rebroadcasting parameters and GPS DC data. IS-QZSS Ver. 1.4 124 5.6.2.1.4 TOW count The 17-bit TOW (Time of Week) count that follows the message type ID in each frame indicates the time at the beginning of the next frame, which is six times that value. This is the same as Section 20.3.3 in Applicable Document (2). 5.6.2.1.5 "Alert" flag The 1-bit "Alert" flag that follows the TOW count in each frame is in accordance with Section 5.1.2.1.3. 5.6.2.1.6 FEC and parity algorithm The CNAV will be encoded with FEC. The algorithm for encoding is the same as in Section 3.3.3.1.1 of Applicable Document (2). The 24-bit parity code added after the 300-bit frame. The parity algorithm is the same as in Section 20.3.5 of Applicable Document (2). 5.6.2.2 Message content With the exception of the list in Section 8.1.2, the content of the message is the same as in Applicable Document (2). 5.6.2.2.1 Ephemeris data and health for message types 10 and 11 5.6.2.2.1.1 Content of Ephemeris data and health for message types 10 and 11 Message types 10 and 11 include the Ephemeris data (such as that shown in Table 5.6.2-3) for the corresponding satellite. The general content is the same as Section 20.3.3.1 in Applicable Document (2). IS-QZSS Ver. 1.4 125 Table 5.6.2-3 Definition of Ephemeris parameters for Navigational Message D L5 Parameter Definition Difference from GPS definition 10 WN n GPS Week Number 10 L1/L2/L5 Health L1, L2 and L5 signal health 10 t op Data predict time of week (seconds into week) 10 URA oe index Ephemeris accuracy index 10 11 t oe Ephemeris epoch (seconds into week) 10 AA Difference from semi major axis at t oe In the case of QZS, indicates difference with 42,164,200 [m] In the case of GPS, indicates difference with 26,559,710 [m] 10 A  Change rate in semi major axis 10 An 0 Difference from mean motion calculation at t oe 10 0 n A Change rate from mean motion calculation 10 M 0-n Mean anomaly at t oe 10 e n Eccentricity 10 ω n Argument of perigee 11 Ω 0-n Longitude of ascending node at the beginning of the week 11 i 0-n Orbit inclination in t oe 11 AΩ ． Rate of Right ascension of ascending node (RAAN) difference from reference value * 11 i o-n -DOT Change rate in orbit inclination 11 C is-n Amplitude of the sine harmonic correction term to the angle of inclination 11 C iｃ-n Amplitude of the cosine harmonic correction term to the angle of inclination 11 C ｒs-n Amplitude of the sine correction term to the orbit radius 11 C ｒc-n Amplitude of the cosine correction term to the orbit radius 11 C us-n Amplitude of the sine harmonic correction term to the argument of latitude 11 C uc-n Amplitude of the cosine harmonic correction term to the argument of latitude * Relative to ] cond circles/se - semi [ 10 6 . 2 9 ÷ × ÷ = O REF  (same value with GPS) (1) Transmission Week Number Bits 39 - 51 in message type 10 constitute a binary expression for the 8192 remainder of the current GPS Week Number. This is the same as Section 20.3.3.1.1.1 in Applicable Document (2). IS-QZSS Ver. 1.4 126 (2) Signal health (L1/L2/L5) The three single bits from bit 52 to bit 54 in message type 10 indicate the health of the L1, L2 and L5 signals, respectively, transmitted by the corresponding satellite. The value for the L1 signal is "1" in the event that there is a problem with one or more of the L1C/A, L1-SAIF or L1C signals. 0 No problems with signal 1 Problem with signal exists or signal cannot be used These bit indices are compared to the monitoring results at the present time for the corresponding satellite. The details are in accordance with Section 5.1.2.1.3. Health data are also present in message types 12, 31 and 37. The data in message type 10 are uploaded at a different time, so the data may differ from that for the transmission satellites of other messages and other satellite data. (3) Data Predict Time of week: op t Bits 55-65 in message type 10 indicate the data predict time of week ( op t ). The op t term provides the epoch time of week of the state estimate utilized for the prediction of satellite ephemeris parameters. This is the same as in Section 20.3.3.1.1.3 of Applicable Document (2). (4) Accuracy indicator for Ephemeris data: oe URA index Bits 66-70 in message type 10 indicate the SIS accuracy indicator for Ephemeris data. For more information, see Section 5.1.2.1.3.2. (5) Ephemeris data epoch: oe t Bits 71 - 81 in message type 10 and bits 39 - 49 in message type 11 indicate the epoch for Ephemeris data. This is the same as Table 20-I in Applicable Document (2). (6) Ephemeris data After the URA oe index in message type 10, the Ephemeris data (shown in Table 5.6.2-3) for the corresponding satellite are transmitted. In the data, ΔA represents the value of the Semi-Major Axis in the context of t oe , ( ) oe t A , minus 42,164,200 [m]: ( ) ( ) ] [ 200 , 164 , 42 m t A t A oe oe ÷ = A Other values are the same as Table 20-I in Applicable Document (2). 5.6.2.2.1.2 Characteristics of Ephemeris Data Parameters for Message Types 10 and 11 With the exception of those items shown in the previous section (Section 5.6.2.2.1.1), the parameter characteristics for message types 10 and 11 (number of bits, LSB scale factor, data range and units) are the same as Table 20-I in Applicable Document (2). Bit allocation for message types 10 and 11 is the same as Figure 20-1 and 20-2 in Applicable Document (2). However, Integrity Status Flag and L2C Phasing Flag were added in Figure 20-1 of Applicable Document (2), QZS-1 did not adopt. After "Phase Two", adoption of the Integrity Status flag is under study, but L2C Phasing Flag will not be adopted. 5.6.2.2.1.3 Message Types 10 and 11: User Algorithms for Satellite Positioning In accordance with Section 6.3.5. IS-QZSS Ver. 1.4 127 5.6.2.2.2 Message types 30 through 35, 37, 46, 47, 49, 51 and 53: SV Clock Correction Parameters 5.6.2.2.2.1 Message types 30 through 35, 37, 46, 47, 49, 51 and 53: Content of SV Clock Parameters Message types 30, 31, 32, 33, 34, 35, 37, 46, 47, 49, 51 and 53 all contain SV clock parameters for the corresponding satellite such as those shown in Table 5.6.2-4. For an overview, see Section 20.3.3.2 in Applicable Document (2). Table 5.6.2-4 Definition of SV clock parameters for Navigational Message D L5 Parameter Definition Difference from GPS definition ｔ oc SV clock parameter epoch (seconds into week) URA OC index SV clock accuracy index URA OC1 index SV clock accuracy change index URA OC2 index SV clock accuracy change rate index a f0-n SV clock bias correction term a f1-n SV clock drift correction term a f2-n SV clock drift rate correction term (1) Data predict time of accuracy indicator for SV clock parameters (t op ) Bits 39 - 49 indicate the data predict time of week (t op ) for the accuracy indicator for the SV clock parameters. (2) SV clock parameter accuracy indicator (URA oc index) Bits 50 - 60 include the parameter needed to determine the SIS accuracy of the SV clock parameters (URA oc ). Details are in accordance with Section 5.1.2.1.3.2. (3) SV clock parameter epoch (t oc ) Bits 61 - 71 constitute the SV clock parameter epoch t oc . (4) SV clock parameter The SV clock parameter for the corresponding satellite, shown in Table 5.6.2-4, will be transmitted. The user algorithm is the same as Section 20.3.3.2.4 in Applicable Document (2). However, certain parts of the definition are different; for more information, see Section 6.3.2. 5.6.2.2.2.2 Message types 30 through 35, 37, 46, 47, 49, 51 and 53: Characteristics of SV Clock Parameters With the exception of those items shown in the previous section (Section 5.6.2.2.2.1), the parameter characteristics for message types 30, 31, 32, 33, 34, 35, 37, 46, 47, 49, 51 and 53 (clock correction parameter number of bits, LSB scale factor, data range and units) are the same as those shown in Applicable Document (2) (Table 20-III). IS-QZSS Ver. 1.4 128 5.6.2.2.2.3 Message types 30 through 35, 37, 46, 47, 49, 51 and 53: User Algorithm for SV Clock Correction Data (1) Calculation of Accuracy for SV Clock Parameter: URA oc calculation. The algorithm used to determine the detailed user positioning accuracy (URA oc ) expressed by URA oc index is the same as Section 20.3.3.2.4 in Applicable Document (2). For more information about how to use URA oc , see Section 3.1.2.1.3. For more information about the content of URA oc , see Section 5.1.2.1.3. Note: Refer to the above Applicable Document (2), URA oc is calculated in quadratic equation of the time. The coefficient of the linear term and that of quadratic term become larger than 0 by definition. The value of the linear term would become larger than 1.7578 m after 3600 seconds from the t op because t op is updated every 3600 seconds for QZSS. (2) Calculation of SV clock offset using SV clock parameters As this is an estimate by the Control Segment by means of the L1C/A signal and the L2C signal code measurement, there are additions to the SV clock correction algorithm for one-signal users and 2-signal (L1C/A and L2C) users. See Section 6.3.2 for details. 5.6.2.2.3 Message Type 30, 46: Ionospheric Parameter and Group Delay Correction Parameter In addition to the SV clock parameters (Section 5.6.2.2.2), message type 30 includes the ionospheric parameters like those shown in Table 5.6.2-5 and the internal signal group delay correction parameters shown in Table 5.6.2-6. For more information regarding the content of these parameters, see Section 20.3.3.3 in Applicable Document (2). Ionospheric parameters in Message type 46 are rebroadcast of parameters broadcasted by GPS. Since Group Delay Correction parameters broadcasted by GPS is NOT rebroadcasted by QZSS, bits 128 to 192 in message type 46 can NOT be used. Table 5.6.2-5 Definition of ionospheric parameters for Navigational Message D L5 Parameter Definition Difference from GPS definition α 0 Ionospheric parameter α 0 for Klobuchar model Coefficient optimized for Japan & environs α 1 Ionospheric parameter α 1 for Klobuchar model Coefficient optimized for Japan & environs α 2 Ionospheric parameter α 2 for Klobuchar model Coefficient optimized for Japan & environs α 3 Ionospheric parameter α 3 for Klobuchar model Coefficient optimized for Japan & environs β 0 Ionospheric parameter β 0 for Klobuchar model Coefficient optimized for Japan & environs β 1 Ionospheric parameter β 1 for Klobuchar model Coefficient optimized for Japan & environs β 2 Ionospheric parameter β 2 for Klobuchar model Coefficient optimized for Japan & environs β 3 Ionospheric parameter β 3 for Klobuchar model Coefficient optimized for Japan & environs IS-QZSS Ver. 1.4 129 Table 5.6.2-6 Group Delay Correction Parameters (T GD , ISC) for Navigational Message D L5 Parameter Definition Difference from GPS definition T GD LC QZSS and L1C/A group delay LC GPS and L1P(Y) group delay for GPS ISC L1C/A N/A (Broadcasting value is 0.0) L1P(Y) - L1C/A for GPS ISC L2C L1C/A – L2C group delay L1P(Y) – L2C for GPS ISC L5I5 L1C/A - L5I5 group delay L1P(Y) – L5I5 for GPS ISC I5Q5 L1C/A - L5Q5 group delay L1P(Y) – L5Q5 for GPS LC QZSS ： LC QZSS is the ionospheric error free linear combination of the L1C/A and L2C signals for QZSS LC GPS ： LC GPS is the ionospheric error free linear combination of the L1P(Y) and L2P(Y) signals for GPS (1) Ionospheric parameters This section provides the ionospheric parameters used by one-signal users (who use only the L1, L2 or L5 signal) when they use an ionospheric model to calculate the ionospheric delay. These parameters are specialized to fit the geographic area shown in Figure 4.1.5-1. User algorithms for one-signal users are in accordance with Sections 6.3.4 and 6.3.8. These parameters use data from the past 24 hours (Maximum) and are updated at least once per day except “ionospheric maximum periods”. The number of bits, scale factor, ranges and units are the same as Table 20-IV in Applicable Document (2). (2) Estimating the L1-L5 group delay error Group delay error terms T GD , ISC L5I5 and ISC L5Q5 for users of only one signal (L5) and L1/L5 users are contained in bits 128-140, 167-192 of message type 30. Table 20-IV in Applicable Document (2) shows the number of bits, scale factor, range and units. "Bit string "1000000000000" indicates that the group delay value cannot be used. The relevant algorithms are shown in Sections 6.3.3 and 6.3.4. 5.6.2.2.4 Message Types 31, 12, 37, 47, 28 and 53: Almanac Data QZS Almanac data are provided by message types 31, 12 and 37. The Reduced Almanac is provided by message type 31 or 12, and the Midi Almanac is provided by message type 37. The PRN number for these message types indicates the last 6 bits of the QZS PRN. Almanac data for other satellite positioning systems are provided by message types 47, 28 and 53. The Reduced Almanac is provided by message type 47 or 28, and the Midi Almanac is provided by message type 53. Of the PRN numbers for these message types, numbers 1-32 are for GPS satellites. The Reduced Almanac for satellites is broadcast by a single satellite in a shorter interval than the Midi Almanac. IS-QZSS Ver. 1.4 130 Table 5.6.2-7 Definition of Midi Almanac parameters for Navigational Message D L5 Parameter Definition Difference from GPS definition WN a-n GPS Week Number at the time of Midi Almanac generation t oa Midi Almanac epoch (second in week) PRN no. When the message type number is 37, it indicates that this value is for a QZS satellite and constitutes the offset value from the PRN number of 193 for the target satellite. When the message type number is53, it indicates that this value is the PRN value for a GPS satellite. L1/L2/L5 Health L1, L2 and L5 signal health E Eccentricity (offset from the nominal QZS eccentricity of 0.06) Only values up to 0.03 can be expressed in the case of GPS i o Offset from the reference QZS orbit inclination (0.25 [semi-circles]) （Offset from 0.25 [semi-circles]=45 [deg]） In the case of GPS, the reference inclination is 0.3 [semi-circles], which represents 54 [deg]. O  Change rate in right ascension of ascending node (RAAN) A Square root of Semi-Major Axis 0 O Longitude of ascending node at the beginning of the week e Argument of perigee M 0 Mean anomaly a f0 Bias term for SV clock a f1 Drift term for SV clock Table 5.6.2-8 Definition of Reduced Almanac parameters for Navigational Message D L5 Parameter Definition Difference from GPS definition WN a-n GPS Week Number at the time of Reduced Almanac generation t oa Reduced Almanac epoch (second in week) PRN no. When the message type number is 31 or 12, it indicates that this value is for a QZS satellite and constitutes the offset value from the PRN number of 193 for the target satellite. When the message type number is 47 or 28, it indicates that this value is the PRN value for a GPS satellite δA Offset from the nominal QZS Semi-Major Axis of 42,164,200 [m] In the case of GPS, indicates the offset from 26,559,710 [m] Ω 0 Longitude of ascending node at the beginning of the week Φ 0 Argument of latitude (= M 0 + w) Based on the assumption that ω= 270 [deg] L1/L2/L5 Health L1, L2 and L5 signal health (e) Implicit eccentricity (0.075 in the case of QZS) (precondition for above parameter) 0 in the case of GPS (δi) Fixed at -0.0111 [semi-circles], the offset from the reference QZS orbit inclination of 0.25 [semi-circles] (precondition for above parameter) In the case of GPS, fixed at +0.0056 [semi-circles], the offset from 0.3 [semi-circles] (ω) Implicit Argument of Perigee (270 [deg] in QZS-1 ） （Precondition for above parameters） 0 [deg] in case of GPS IS-QZSS Ver. 1.4 131 5.6.2.2.4.1 Almanac Reference Week Number Bits 39 - 51 in message types 12 and 28 and bits 128 - 140 in message types 31 and 37 (and 47 and 53) indicate the Week Number (WN a-n ) that serves as a reference for the Almanac reference time (t oa ). WN a-n is made up of 13 bits and is expressed by the modulo-8192 GPS Week Number (see Section 6.3.6) that serves as a reference for t oa . 5.6.2.2.4.2 Almanac reference time Bits 52-59 in message type 12 (and 28) and bits 141-148 in message types 31 and 37 (and also 47 and 53) indicate the Almanac reference time (t oa ). 5.6.2.2.4.3 Satellite PRN number The first 6 bits in the 31-bit Reduced Almanac included in message types 31 and 12 (and also 47 and 28) constitute the corresponding satellite’s PRN. In the case of message types 31 and 12, the PRN constitutes the last 6 bits of the QZS PRN. In the case of message types 47 and 28, the PRN is a GPS PRN. There is a PRN in bits 149-154 of the Midi Almanac included in message type 37 (and 53). In the case of message type 37, the PRN constitutes the last 6 bits of the QZS PRN. In the case of message type 53, the PRN number 1 to 32 is a GPS PRN number. If the Almanac data is not effective, the value of the PRN Number is set to “111111” as in Applicable Document (3). In this event, the remainder of the rest of 22 bits in the data block shall be filler bits, i.e., alternating ones and zeros beginning with one, and the 3-Bit-Health is set to “111” (cf. Section 5.5.2.2.4.4). 5.6.2.2.4.4 Signal health (L1/L2/L5) The three 1-Bit Health indicators – bits 155, 156 and 157 in message type 37 (and 53) and bits 29, 30 and 31 in the Reduced Almanac in message types 31 and 12 (and 28) relate to the L1, L2 and L5 signals for the satellite corresponding to the PRN number. Their meaning is covered in Section 5.1.2.1.3. 5.6.2.2.4.5 Midi Almanac data content Message type 37 (and 53) provides the Almanac for the satellite with the PRN number shown in the message. The number of bits, scale factor, ranges and units are the same as Table 20-V in Applicable Document (2). However, the QZS eccentricity and inclination differs from that of GPS and is provided relative to the reference values as noted below. (1) Eccentricity (a) In the case of QZSS: nav e 0.06+ = a e (b) In the case of GPS: nav e 0.00 + = a e Reference in accordance with Applicable Document (2) a e : Actual eccentricity value nav e : Eccentricity value included in navigation message IS-QZSS Ver. 1.4 132 (2) Inclination (a) In the case of QZSS: ] [ 25 . 0 circle semi i i a ÷ + = o (b) In the case of GPS: ] [ 3 . 0 circle semi i i a ÷ + = o Reference in accordance with Applicable Document (2) i a : Actual inclination value i o : Inclination value included in navigation message For the user algorithm, see Section 6.3.6. The Midi Almanac for the QZS data is updated approximately once every 3.5 days. The velocity calculated by the Midi Almanac data is accurate within 30m/s. 5.6.2.2.4.6 Content of Reduced Almanac Data Message type 31 and 12 (and also 47 and 28) contain multiple reduced Almanac data values. Reduced Almanac data values are provided relative to reference values as shown below. (1) Semi-Major Axis (a) For QZSS: A [m] 42,164,200 A o + = (b) For GPS: A [m] 26,559,710 A o + = Reference in accordance with Applicable Document (2) (2) Eccentricity (a) For QZSS: 0.075 = e (b) For GPS: 0.0 = e Reference in accordance with Applicable Document (2) (3) Orbit Angle of Elevation (a) For QZSS: [deg] 43 = i (b) For GPS: [deg] 55 = i Reference in accordance with Applicable Document (2) (4) Time change rate for right ascension of ascending node (RAAN) (a) For QZSS: ] conds circles/se semi [ 10 7 8. 10 ÷ × ÷ = O ÷  (b) For GPS: ] conds circles/se semi [ 10 6 . 2 9 ÷ × ÷ = O ÷  Reference in accordance with Applicable Document (2) (5) Implicit Argument of Perigee (a) For QZSS: [deg] 270 = e (b) For GPS: [deg] 0 = e The number of bits, LSB scale factor, ranges and units are the same as Table 20-VI in Applicable Document (2). For the user algorithm, see Section 6.3.6. The Reduced Almanac data for the QZS are updated approximately every 3.5 days. The velocity calculated by the Reduced Almanac data is accurate within 350 m/s. IS-QZSS Ver. 1.4 133 5.6.2.2.5 Message type 32: Earth Orientation Parameter (EOP) The Earth Orientation Parameter is included in message type 32. The definition, number of bits, scale factor, range, units, LSB, user algorithm, etc., for this parameter are all the same as Section 20.3.3.5 in Applicable Document (2). 5.6.2.2.6 Message type 33, 49: UTC Parameters The UTC parameters are included in message type 33 (and 49). When the Message Type = 33, the UTC parameters transmitted by the QZS is needed to link GPS time to UTC (NICT). When the Message Type = 49, those are gathered by receiving GPS signals at QZS Monitor Stations and re-broadcasted to link GPS time to UTC (USNO). The number of bits, scale factor, range, units, LSB, user algorithm, etc., for this parameter are all the same as Section 20.3.3.6 in Applicable Document (2). 5.6.2.2.7 Message Type 34, 13, 14: Differential Correction Data (DC Data) Differential correction data (DC data) are included in message types 34, 13 and 14. These parameters provide users with correction terms for SV clock parameters and Ephemeris data transmitted by other satellites. DC data is divided into packets that comprise a 34-bit SV clock error correction (CDC) parameter and a 92-bit Ephemeris error correction (EDC) parameter. CDC and EDC data are paired, and users must use the CDC and EDC pair corresponding to the same t op-D and t OD . Message type 34 includes the CDC and EDC for one satellite. Message type 13 includes the CDC data for six satellites, while message type 14 includes the EDC data for two satellites. A DC Type indicator "0" indicates that the corresponding correction parameters should be applied to CNAV data, while "1" indicates that the corrections should be applied to the navigation message for the L1C/A signal. The content of the data packets is the same as Section 20.3.3.7 in Applicable Document (2). The content is shown in Table 5.6.2-9. The bit definition, number of bits, scale factor and unit for DC data are the same as Figure 20-17 and Table 20-X in Applicable Document (2). If the DC data is not effective, the value of the PRN Number is set to “11111111” as Section 20.3.3.7.2.3 in Applicable Document (2). In this case, DC type indicator is set to “0”. IS-QZSS Ver. 1.4 134 Table 5.6.2-9 Definition of parameters for DC data for Navigational Message D L5 Parameter Definition Difference from GPS definition ｔ op-D Prediction time of week for DC data (seconds in week) t OD Reference time of week for DC data (seconds in week) DC Type Indicator 1: For D LIC/A message 0: For D L5 message PRN no. PRN no. (range 0 - 255) for satellite for which DC data will be applied 1 - 32 if GPS; 193 – 202 if QZSS f0 a o Bias term for SV clock f1 a o Drift correction term for SV clock UDRA index User Differential Range Accuracy (UDRA) index o A o correction term for Ephemeris parameter | A | correction term for Ephemeris parameter ¸ A ¸ correction term for Ephemeris parameter i A Correction term for orbit inclination AO Correction term for right ascension of ascending node (RAAN) A A Correction term for Semi-Major Axis UD ． RA index UDRA rate index 5.6.2.2.7.1 Differential Correction (DC) data DC data include the following. For more information regarding the use of DC data, see Section 3.1.2.1.3.4. (1) Time of DC data estimation ( D op t ÷ ) “ D op t ÷ ” indicates the time (seconds into week) at which DC data were estimated. This value is the same as Section 20.3.3.7.2.1 in Applicable Document (2). (2) DC data epoch ( OD t ) “ OD t ” indicates the epoch (seconds into week) for DC data. This value is the same as Section 20.3.3.7.2.2 in Applicable Document (2). (3) Satellite PRN identification The 8-bit PRN specifies the satellite for which the corresponding DC data set is to be used. When PRN is 1-32, it indicates GPS; when PRN is 193-197, it indicates QZSS. If the bit values are all set to "1", then there are no DC data in the data block. This is the same as Section 20.3.3.7.2.3 in Applicable Document (2) in the sense that the remaining data consist of alternating bit values of "1" and "0". (4) Use of CDC data Same as Section 20.3.3.7 in Applicable Document (2). For more information, see Section 6.3.9.2. IS-QZSS Ver. 1.4 135 (5) Use of EDC data Same as Section 20.3.3.7 in Applicable Document (2). For more information, see Section 6.3.9.2. 5.6.2.2.7.2 DC Data Accuracy The User Differential Range Accuracy, UDRA op-D , and its time derivative, UD ． RA, indicate the positioning accuracy after DC data have been applied to the SV clock parameter and Ephemeris data. The bit definition, number of bits, etc., and user algorithm are the same as Section 20.3.3.7.5 in Applicable Document (2). For more information regarding the use of UDRA op-D and UD ． RA, see Section 3.1.2.1.3.5. 5.6.2.2.8 Message type 35, 51: GPS/GNSS time offset: GGTO Message type 35 (and 51) is the parameter used to adjust GPS time to match other GNSS times. The bit definition, number of bits, scale factor (LSB), range and units are all the same as Table 02-XI in Applicable Document (2). The effective period for GPS GNSS Time Offset (GGTO) is at least 24 hours. Table 5.6.2-10 Definition of GPS GNSS Time Offset (GGTO) parameters for Navigational Message D L5 Parameter Definition Difference from GPS definition ｔ GGTO Seconds into GGTO reference week WN GGTO GGTO reference Week Number GNSS ID See Section 5.6.2.2.8.1 A 0GGTO GPST bias term associated with the other GNSS A 1GGTO GPST drift term associated with the other GNSS A 2GGTO GPST drift rate term associated with the other GNSS 5.6.2.2.8.1 GNSS - ID Bits 155-157 in message type 35 define the other satellite positioning systems to which data offsets with respect to GPS are applied. The definitions of these three bits are as follows. 000 Data cannot be used 001 Galileo 010 GLONASS 011 QZSS 100 - 111 Spare 5.6.2.2.8.2 GPS/GNSS Time Offset The algorithm used to determine GPS GNSS Time Offset (GGTO) is the same as Section 20.3.3.8 in Applicable Document (2). However, the QZS SV clock parameter already uses GPST as the reference, so the time offset value for GPS and QZSS (GQTO) is zero. 5.6.2.2.9 Message Types 15: Text Messages Text messages are transmitted using the 29 8-bit ASCII characters in message type 15. The bit definition, number of bits, etc., is the same as Figure 20-14 in Applicable Document (2). IS-QZSS Ver. 1.4 136 5.7 LEX signal 5.7.1 RF Signal Characteristics 5.7.1.1 Signal Configuration The LEX signal is modulated by BPSK (5), as specified in Section 5.1. As shown in Figure 5.7.1-1, the LEX baseband signal, C LEX , is generated with a chipping rate of 5.115 MChip/s by interleaving the following two 2.5575 Mcps bit streams: (a) a 4ms PRN Short Code modulated by means of code shift keying (CSK) by the Reed-Solomon encoded Navigation message, and (b) a 410 ms PRN Long Code modulated by squarewave with a period of 820 ms beginning from 0 ("010101..."). As defined in Figure 5.7.1-1, CSK modulation shifts the phase of the PRN code by the number of chips indicated by the 8-bit encoded Navigational message symbol. Nav Message 8bits/Symbol Reed-Solomon(255,223) Coding CSK Modulator (*) Long Code (410ms) : 2.5575MChip/s Short Code (4ms) : 2.5575MChip/s 1744 Bits/s 250 Symbols/s (2000 Bits/s) 2.5575MChip/s Clock 5.115MHz MSB PRN(1) PRN(10230) PRN(N+1) PRN(102３０) PRN(1) PRN(N-1) PRN(N) 8 Bits (1Symbol) Value = N (as Decimal：N=0 - 255) Nav Message Data Original PRN Code Pattern CSK Modulated PRN Code Pattern by “N” value LSB 4 ms Code Phase Shift by CSK Modulation Time (*) Definition of Code shift Keying (CSK) Modulation LEX C 5.115 MChip/s Ranging Code Generator Squarewave which starts from “0” ie. “010101…” 820ms period 2.5575MChip/s Nav Message 8bits/Symbol Reed-Solomon(255,223) Coding CSK Modulator (*) Long Code (410ms) : 2.5575MChip/s Short Code (4ms) : 2.5575MChip/s 1744 Bits/s 250 Symbols/s (2000 Bits/s) 2.5575MChip/s Clock 5.115MHz MSB PRN(1) PRN(10230) PRN(N+1) PRN(102３０) PRN(1) PRN(N-1) PRN(N) 8 Bits (1Symbol) Value = N (as Decimal：N=0 - 255) Nav Message Data Original PRN Code Pattern CSK Modulated PRN Code Pattern by “N” value LSB 4 ms Code Phase Shift by CSK Modulation Time (*) Definition of Code shift Keying (CSK) Modulation LEX C LEX C 5.115 MChip/s Ranging Code Generator Squarewave which starts from “0” ie. “010101…” 820ms period 2.5575MChip/s Figure 5.7.1-1 LEX Signal Structure IS-QZSS Ver. 1.4 137 5.7.1.2 Carrier Wave Properties In accordance with Section 5.1. 5.7.1.3 Code Properties 5.7.1.3.1 Overview of LEX Code As shown in Figure 5.7.1-2, the LEX signal code comprises a Kasami series Short Code (2.5575 MChip/s) with a chip length of 10,230 and a 4 ms period, and a Kasami series Long Code (2.5575 MChip/s) with a chip length of 1,048,575 and a 410 ms period. I Short Code : 2.5575MChip/s R 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 2.5575MHz C I R 1 2 3 4 5 6 7 8 9 10 C I Long Code : 2.5575MChip/s R 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 C 1048575 Count 10230 Count Week reset Command Register Inputs I - Input R - Reset to initial conditions C - Clock Initial Phase Register XOR Initial Phase Register Week reset port Counter G(X)=X20+X19+X16+X14+1 G(X)=X20+X19+X16+X14+1 G(X)=X10+X9+X6+X5+X4+X3+1 XOR XOR Initial Phase Register = All 1's + + OR Figure 5.7.1-2 Block diagram of LEX code generation 5.7.1.3.2 Code Generation Separate 20-bit stage code generators are used to generate the two code patterns (Short Code and Long Code). The satellite numbers (PRN numbers) are identified by the default settings for each of these code generators. Table 5.7.1-1 shows the default values corresponding to the QZS satellite numbers. The initialization period for each code generator is 4 ms in the case of the Short Code generator and 410 ms in the case of the Long Code generator. Both the Short Code generator and the Long Code generator are initialized at the end/beginning of the week. Figure 5.7.2-3 shows the timing relationship between the LEX Short Code and Long Code. IS-QZSS Ver. 1.4 138 The PRN number is in accordance with Section 5.1.1.11.2. Table 5.7.1-1 LEX code phase assignment QZS SV ID PRN No. Initial shift register state Short (Octal) Long (Octal) 1 193 0255021 0000304 2 194 0327455 0237663 3 195 0531421 0467237 4 196 0615350 0550370 5 197 0635477 1703243 The first digit in the octal notation represents first two chip (i.e. Most significant digit “0” in the binary notation shall be ignored) For example.：In the case of 3742246 in the octal notation, the first 20 chips are '11 111 100 010 010 100 110' in the binary notation End/Start of Week End/Start of Week Nav Message LEX Short Code LEX Long Code 1 0 Squarewave LEX Short Code LEX Long Code LEX Signal (Chip by Chip Multiplexed Sinal) The first LEX Short Code starts synchronously with the end/start of week epoch ・・・・・・ ・・・・・・ L S L Short Short Long Long Long S L S 1 Symbol 10230 Chips 1048575 Chips Short ・・・・・・ ・・・・・・ ・・・・・・ 1 Symbol 10230 Chips 10230 Chips 1 Symbol 1 Symbol 10230 Chips 1 Symbol 1 Symbol 1 Symbol 1 Symbol 10230 Chips 10230 Chips 10230 Chips 1 Symbol 1 Symbol 1 Symbol 1 Symbol 10230 Chips 10230 Chips 10230 Chips 10230 Chips 10230 Chips 1048575 Chips 1048575 Chips 997425 Chips 10230 Chips 10230 Chips 10230 Chips 1 Symbol 1 Symbol 1 Symbol 4 ms 410 ms 820 ms 390 ms 391 ns (=1/2.5575MHz) 195.5 ns (=1/5.115MHz) Figure 5.7.1-3 Timing Relationship between the LEX Short Code and Long Code 5.7.1.3.3 Non-Standard Code In the event that a problem with the QZSS occurs, a non-standard code (NSC) is transmitted. This is done to protect the user by ensuring that users do not use erroneous signals. IS-QZSS Ver. 1.4 139 5.7.2 LEX Messages 5.7.2.1 Message Structure The LEX message signal structure is shown in Figure 5.7.2-1. Each message is made up of a total of 2,000 bits: a 49-bit header, a 1695-bit data section and a 256-bit Reed-Solomon code. Transmission of each Navigation message takes one second. 1 50 1745 1 33 41 49 "Alert" Flag - 1 Bit Data Part (1695 Bits) Header (49 Bits) Reed-Solomon Code (256 Bits) Preamble 32 Bits PRN 8 Bits Message Type ID 8 Bits 1 seconds DIRECTION OF DATA FLOW FROM SV 2000 Bits MSB LSB Figure 5.7.2-1 LEX Message Structure 5.7.2.1.1 Preamble At the beginning of each message is the 32-bit preamble. The value of the preamble is 00011010110011111111110000011101. 5.7.2.1.2 PRN No. Each message has an 8-bit PRN number immediately following the preamble. The PRN number is the PRN number for the satellite transmitting that message. 5.7.2.1.3 Message Type ID Each message has an 8-bit message type ID immediately following the PRN number. The message type ID signifies the information included in that frame. Table 5.7.2-1 shows the relationship between the message type ID and the information. IS-QZSS Ver. 1.4 140 Table 5.7.2-1 Definition of message type Message type Content Notes 0-9 Spare （System use） 10-19 10 Signal health （35 satellites） Ephemeris & SV clock （3 satellites） For JAXA experiment 11 Signal health （35 satellites） Ephemeris & SV clock （2 satellites） Ionospheric correction 12～19 Spare 20 For experiment by Geographical Survey Institute 21～155 For experiment For experimental user except JAXA , GSI and users of application demonstration in private sector 156 - 255 For application demonstration in private sector For experimental users of application demonstration in private sector by means of performance enhancement signal 5.7.2.1.4 Alert Flag Each message has a 1-bit alert flag immediately following the message type ID. The alert flag indicates the signal power of the LEX signal for that satellite and the health status of the data. During the experiment using message type 20 carried out by GSI, this “alert flag” bit is used for the identification which relevant data part is head of a message record or not. The data part includes the head of the message record if this bit is “1”, otherwise it is continuous message following previous message. IS-QZSS Ver. 1.4 141 5.7.2.1.5 FEC Encoded Algorithm Reed-Solomon (255, 223) encoding is applied the 1,744 bits of the Navigation message (preamble, PRN, message type ID, alert flag and data section). Every 8 bits of the resulting bit-stream comprises one symbol. (see Section 6.5.1 for details) In order to add the 32-symbol (256-bit) Reed-Solomon code to the 218-symbol (1,744-bit) Navigation message, nine "0" symbols (72 bits) are inserted at the beginning of the 214-symbol (1,712-bit) data bit string that does not include the 4-symbol (32-bit) preamble at the beginning of the header. The resulting 223-symbol (1,784-bit) data bit string (with the 9 zero symbols inserted) is Reed-Solomon encoded (255,223) to generate a 32-symbol (256-bit) parity word. The 250 symbols (2,000 bits) that comprise the 32-symbol parity words added to the original 218-symbol (1,744-bit) data bit string (including the preamble) are then input to the CSK Modulator (see Figure 5.7.2-2). 214 Symbols (1712 Bits) Parity (RSC) 32 Symbols (256 Bits) Zero “0” 9 Symbols Data Part 1695 Bits Header 49 Bits Preamble 4 Symbols (32Bits) Data Part 1695 Bits Data Part 1695 Bits Preamble 4 Symbols (32Bits) Header 49 Bits Insert Zero “0” Symbol – 9 Symbols (72 Bits ) Delete Zero “0” Symbol – 9 Symbols (72 Bits ) 223 Symbols (1784 Bits) 250 Symbols (2000 Bits) Broadcast Original Bit Strings GF(2 8 ) RS(255,223) Encode 218 Symbols (1744 Bits) Figure 5.7.2-2 Reed-Solomon Encoding IS-QZSS Ver. 1.4 142 5.7.2.2 Message Content 5.7.2.2.1 Message types 10 and 11 Message types 10 and 11 are JAXA test messages. The 1,695-bit data section of message type 10 includes the signal health and Ephemeris & SV clock data as shown in Figure 5.7.2-3. The 1,695-bit data section of message type 11 includes the signal health, Ephemeris & SV clock and ionospheric delay correction data as shown in Figure 5.7.2-4. 21 1 34 50 225 WN - 13 Bits TOW 501 702 1001 1179 1501 1656 Signal Health Packet 175 Bits Ephemeris & SV Clock Packet 3 155 LSBs in 477Bits Reserved 40 Bits Ephemeris & SV Clock Packet 1 276 MSBs in 477Bits Ephemeris & SV Clock Packet 2 299 MSBs in 477Bits Ephemeris & SV Clock Packet 3 322 MSBs in 477Bits Ephemeris & SV Clock Packet 1 201 LSBs in 477Bits Ephemeris & SV Clock Packet 2 178 LSBs in 477Bits 20 Bits t oe 16 Bits DIRECTION OF DATA FLOW FROM SV 500 Bits DIRECTION OF DATA FLOW FROM SV 500 Bits DIRECTION OF DATA FLOW FROM SV 500 Bits DIRECTION OF DATA FLOW FROM SV 195 Bits Figure 5.7.2-3 Data Part, Message Type 10 – Signal Health, Ephemeris & SV Clock IS-QZSS Ver. 1.4 143 21 1 34 50 225 WN - 13 Bits TOW 501 702 1001 1179 1391 1501 Ephemeris & SV Clock Packet 1 276 MSBs in 477Bits Ephemeris & SV Clock Packet 2 299 MSBs in 477Bits Ionospheric Corection Packet 212 Bits Reserved 110 Bits Reserved 195 Bits Ephemeris & SV Clock Packet 1 201 LSBs in 477Bits Ephemeris & SV Clock Packet 2 178 LSBs in 477Bits 20 Bits t oe 16 Bits Signal Health Packet 175 Bits DIRECTION OF DATA FLOW FROM SV 500 Bits DIRECTION OF DATA FLOW FROM SV 500 Bits DIRECTION OF DATA FLOW FROM SV 500 Bits DIRECTION OF DATA FLOW FROM SV 195 Bits Figure 5.7.2-4 Data Part, Message Type 11 – Signal Health, Ephemeris & SV Clock and Ionospheric Correction IS-QZSS Ver. 1.4 144 5.7.2.2.1.1 Content of Message Types 10 and 11 (1) TOW Count The 20-bit Time of Week (TOW) count at the beginning of the data section of message types 10 and 11 indicates the time (seconds into week) at the beginning of the next one-second message. The valid range is from 0 to 604799. The TOW included in the last message of the week is 0. The TOW included in the first message of the week is 1. (2) Transmission Week No. (WN) The 13 bits from bit 21 to bit 33 in the data section of message types 10 and 11 constitute a binary expression for the modulo-8192 GPS Week Number at the start of that message. (3) Epoch for Ephemeris & SV clock parameters (t oe ) The 16 bits from bit 34 through bit 49 in the data section of message types 10 and 11 constitute the epoch for the Ephemeris & SV clock parameters stored in that message. (4) Signal Health Bits 50-224 in the data section of message types 10 and 11 constitute a signal health packet. As shown in Figure 5.7.2-5, the signal health values for the three QZS satellites and the 32 GPS satellites are broadcast in one batch. The signal health for each QZS and GPS satellite is expressed in five bits (made up of five 1-bit signal health flags) indicating the health of the L1, L2, L5, L1C and LEX signals in that order. When there is a problem with the signal for the corresponding satellite, the 1-bit signal health flag for the L1, L2, L5 or L1C signal will be set to "1”. In such cases, the pseudorange for that signal for the corresponding satellite must not be used for range calculations. The 1-bit signal health flag for the LEX signal changes to "1" when there is a problem with the Ephemeris & SV clock parameters for that satellite that are being broadcast by the QZS. In such cases, the LEX signal (from that satellite) must not be used for range calculations. Signal Health Flag Value Definition 0 There is no problem with the signal 1 There is a problem with the signal and the data cannot be used (5) Ephemeris & SV Clock Packet Bits 225-701, bits 702-1178 and bits 1179-1655 in the data section of message type 10, and bits 225-701 and bits 702-1178 in the data section of message type 11, each constitute an Ephemeris & SV clock packet. Each Ephemeris & SV clock packet includes a satellite ID for one satellite (SV ID), a User Range Accuracy (URA) indicator, the Ephemeris, the SV clock and the group delay correction parameter. For more information, see Section 5.7.2.2.1.2. (6) Ionospheric Correction Parameter Packet Bits 1179-1390 in the data section of message types 10 and 11 constitute an ionospheric correction packet. For more information, see Section 5.7.2.2.1.3. IS-QZSS Ver. 1.4 145 1 6 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 86 91 96 101 106 111 116 121 126 131 136 141 146 151 156 161 166 171 GPS 16 5 Bits GPS 17 5 Bits GPS 18 5 Bits GPS 19 5 Bits GPS 20 5 Bits GPS 21 5 Bits GPS 22 5 Bits GPS 23 5 Bits GPS 24 5 Bits GPS 25 5 Bits GPS 2 5 Bits GPS 3 5 Bits GPS 4 5 Bits GPS 5 5 Bits QZS 1 5 Bits QZS 2 5 Bits QZS 3 5 Bits GPS 1 5 Bits GPS 6 5 Bits GPS 7 5 Bits GPS 8 5 Bits GPS 9 5 Bits GPS 10 5 Bits GPS 11 5 Bits GPS 12 5 Bits GPS 13 5 Bits GPS 14 5 Bits GPS 15 5 Bits GPS 26 5 Bits GPS 27 5 Bits GPS 28 5 Bits GPS 29 5 Bits GPS 30 5 Bits GPS 32 5 Bits GPS 31 5 Bits DIRECTION OF DATA FLOW FROM SV 50 Bits DIRECTION OF DATA FLOW FROM SV 50 Bits DIRECTION OF DATA FLOW FROM SV 50 Bits DIRECTION OF DATA FLOW FROM SV 25 Bits Figure 5.7.2-5 Signal Health Packet Structure IS-QZSS Ver. 1.4 146 5.7.2.2.1.2 Content of Message Types 10 and 11 (Ephemeris & SV Clock Packet) (1) Ephemeris & SV clock Packet The Ephemeris & SV clock packet for each satellite is made up of 477 bits, as shown in Figure 5.7.2-6. (2) Satellite ID: SV ID The first 8 bits of each Ephemeris & SV clock packet constitute a satellite ID (SV ID). The SV ID indicates the PRN number for the satellite corresponding to that data packet. When the SV ID is set to all 1’s ("11111111"), it indicates that the packet does not contain Ephemeris & SV clock data. In such cases, the remaining data bits of that packet will consist of alternating "1" and "0" values starting with 1. (3) User Range Accuracy (URA) Indicator Bits 9-12 of the Ephemeris & SV clock packet constitute an accuracy indicator for the corresponding satellite. The URA index (N) is an integer from 0 to 15. This value has the following relationship with the user range accuracy (URA) of the satellite. URA index（N） URA (meters) 0 URA ≦ 0.08 1 0.08 ＜ URA ≦ 0.11 2 0.11 ＜ URA ≦ 0.15 3 0.15 ＜ URA ≦ 0.21 4 0.21 ＜ URA ≦ 0.30 5 0.30 ＜ URA ≦ 0.43 6 0.43 ＜ URA ≦ 0.60 7 0.60 ＜ URA ≦ 0.85 8 0.85 ＜ URA ≦ 1.20 9 1.20 ＜ URA ≦ 1.70 10 1.70 ＜ URA ≦ 2.40 11 2.40 ＜ URA ≦ 3.40 12 3.40 ＜ URA ≦ 4.85 13 4.85 ＜ URA ≦ 6.85 14 6.85 ＜ URA ≦ 9.65 15 9.65 ＜ URA （ or no accuracy prediction available） IS-QZSS Ver. 1.4 147 (4) Ephemeris (a) Ephemeris parameter properties The properties of the Ephemeris parameters for message types 10 and 11 (number of bits, LSB scale factor and units) are in accordance with Table 5.7.2-2. (b) User Algorithm for Determining Satellite Position The satellite antenna phase center position in the ECEF system (x, y, z) should be calculated using the following equations. ] [ ) ( 6 1 ) ( 2 1 ) ( 3 2 m t t JERKx t t ACCx t t VELx POSx x oe oe oe ÷ · + ÷ · + ÷ · + = ] [ ) ( 6 1 ) ( 2 1 ) ( 3 2 m t t JERKy t t ACCy t t VELy POSy y oe oe oe ÷ · + ÷ · + ÷ · + = ] [ ) ( 6 1 ) ( 2 1 ) ( 3 2 m t t JERKz t t ACCz t t VELz POSz z oe oe oe ÷ · + ÷ · + ÷ · + = t : Satellite time. This is the same as the t value discussed in Section 6.3.2. For cases when the satellite time value extends beyond the end of the week (and the beginning of the following week), if oe t t ÷ is greater than 302,400 seconds, 604,800 seconds should be subtracted; if t-t oe is less than -302,400 seconds, 604,800 seconds should be added. IS-QZSS Ver. 1.4 148 1 9 13 46 79 URA 101 112 140 168 196 201 220 244 268 288 301 308 328 354 374 387 400 ISCL2C - 1 MSB JERKy 401 413 426 439 452 465 POSy 33 Bits JERKx 20 Bits POSz 22 MSBs POSz 11 LSBs VELx 28 Bits VELy 28 Bits VELz 28 Bits ACCx 5 MSBs SV ID 8 Bits 4 Bits POSx 33 Bits JERKy 13MSBs 7 LSBs JERKz 20 Bits A f0 26 Bits A f1 20 Bits T GD 13 Bits ISC L1C/A 13 Bits ACCy 24 Bits ACCz 24 Bits ACCx 19 LSBs ISC L1CD 13 Bits ISC LEX 13 Bits ISC L2C 12 LSBs ISC L5I5 13 Bits ISC L5Q5 13 Bits ISC L1CP 13 Bits DIRECTION OF DATA FLOW FROM SV 100 Bits DIRECTION OF DATA FLOW FROM SV 100 Bits DIRECTION OF DATA FLOW FROM SV 100 Bits DIRECTION OF DATA FLOW FROM SV 77 Bits DIRECTION OF DATA FLOW FROM SV 100 Bits Figure 5.7.2-6 Ephemeris & SV Clock Packet Content URA index IS-QZSS Ver. 1.4 149 Table 5.7.2-2 Definition of ephemeris parameters for Navigational Message D LEX navigation message Parameter No. of Bits Scale Factor （LSB） Units WN GPS Week Number 13 1 Weeks oe t Ephemeris epoch (seconds into week) 16 15 Seconds SV ID PRN number (range 0 - 255) for satellite for which ephemeris parameter will be applied. 1-32 for GPS; 193-197 for QZSS 8 － － URA index User range accuracy index 4 － － POSx X coordinate : Position coefficient 33 * 2 -6 m POSy Y coordinate : Position coefficient 33 * 2 -6 m POSz Z coordinate : Position coefficient 33 * 2 -6 m VELx X coordinate : Velocity coefficient 28 * 2 -15 m/s VELy Y coordinate : Velocity coefficient 28 * 2 -15 m/s VELz Z coordinate : Velocity coefficient 28 * 2 -15 m/s ACCx X coordinate : Acceleration coefficient 24 * 2 -24 m/s 2 ACCy Y coordinate : Acceleration coefficient 24 * 2 -24 m/s 2 ACCz Z coordinate : Acceleration coefficient 24 * 2 -24 m/s 2 JERKx X coordinate : Jerk coefficient 20 * 2 -32 m/s 3 JERKy Y coordinate : Jerk coefficient 20 * 2 -32 m/s 3 JERKz Z coordinate : Jerk coefficient 20 * 2 -32 m/s 3 * Parameters so indicated are in two’s complement notation. (5) SV Clock Parameter (a) Properties of SV Clock Parameter The properties of the SV clock parameter in message types 10 and 11 (number of bits, LSB scale factor and units) are in accordance with Table 5.7.2-3. (b) User Algorithm for SV Clock Correction With the exception of the relativistic effect, the time offset ) (t t c A with respect to QZSST is calculated using the following equation. The handling of other SV clock offsets is in accordance with Section 6.3.2. ( ) oe f f c t t A A t t ÷ + = A 1 0 ) ( [s] t : Satellite time. This is the same as the t value discussed in Section 6.3.2. For cases when the satellite time value extends beyond the end of the week (and the beginning of the following week), if oe t t ÷ is greater than 302,400 seconds, 604,800 seconds should be subtracted; if t-t oe is less than -302,400 seconds, 604,800 seconds should be added. IS-QZSS Ver. 1.4 150 (6) Group Delay Correction Parameter (a) Properties of Group Delay Correction Parameter The properties of the group delay parameter in message types 10 and 11 (number of bits, LSB scale factor and units) are in accordance with Table 5.7.2-3. If the Group Delay Correction Parameters are set to "1000000000000", this indicates that the group delay parameter cannot be used. (b) Single-Signal User Algorithm for Group Delay Correction Parameter User receivers calculating range using measurements of only the LEX signal pseudorange must use the following equation to correct the SV clock offset for the QZS. For more information on correcting the SV clock offset for GPS, see Applicable Documents (1), (2) and (3). When ranging is conducted by combining different frequency signals from QZS and GPS satellites, the receiver internal group delay must be properly corrected by the user receiver. ( ) r LEX GD c LEX sv t ISC T t t A + + ÷ A = A [s] c t A : Time offset with respect to QZSST with the exception of the relativistic effect r t A : Relativistic effect offset (as shown in Section 6.3.2) (c) Dual-Signal User Algorithm for Group Delay Correction Parameter User receivers calculating range using measurements of the LEX signal pseudorange and the pseudorange of another QZS or GPS signal, must use the following procedure for correction of the ionospheric delay and SV clock offset. In addition, based on the definition of t sv shown in Section 6.3.2, the transmitted values for L1C/A ISC are going to be as follows: 0 ISC A / C 1 L = Correction of the GPS ionospheric delay and SV clock offset is in accordance with Applicable Documents (1), (2) and (3). When ranging is conducted by combining different frequency signals from QZS and GPS satellites, the receiver internal group delay must be properly corrected by the user receiver. IS-QZSS Ver. 1.4 151 (i) Dual-Signal Users of L1C/A and LEX Signals User receivers calculating range using measurements of the L1C/A and LEX signals should use the following equation to correct the ionospheric delay. ( ) ( ) sv GD EX 1 A / C 1 L EX 1 LEX A / C 1 L EX 1 LEX A / C 1 L LEX t c cT 1 ISC ISC c PR PR PR A + ÷ ÷ ÷ + ÷ = ÷ ¸ ¸ ¸ [m] where A / C 1 L LEX PR ÷ : Pseudorange value corrected for the ionospheric delay and SV clock offset LEX A / C 1 L PR , PR : Pseudorange values observed using two signals 2 EX 1 125 154 | . | \ | = ¸ : Square of the ratio of the L1 to LEX signal frequencies sv t A : Time offset with respect to QZSST including relativistic effect r t A : Relativistic effect correction indicated in Section 6.3.2 c : Speed of light indicated in Section 6.1.1 (ii) Dual-Signal Users of L2C and LEX Signals User receivers calculating range using measurements of the L2C and LEX signals should use the following equation to correct the ionospheric delay. ( ) ( ) sv GD 2 EX LEX 2 EX C 2 L LEX 2 EX C 2 L LEX C 2 L t c cT 1 ISC ISC c PR PR PR A + ÷ ÷ ÷ + ÷ = ÷ ¸ ¸ ¸ [m] where LEX C 2 L PR ÷ : Pseudorange value corrected for the ionospheric delay and SV clock offset LEX C 2 L PR , PR : Pseudorange values observed using two signals 2 2 EX 120 125 | . | \ | = ¸ : Square of the ratio of the L1 and L2C to LEX signal frequencies sv t A : Time offset with respect to QZSST including relativistic effect r t A : Relativistic effect correction indicated in Section 6.3.2 c : Speed of light indicated in Section 6.1.1 IS-QZSS Ver. 1.4 152 (iii) Dual-Signal Users of L5 and LEX Signals User receivers calculating range using measurements of the L5 and LEX signals should use the following equation to correct the ionospheric delay. ( ) ( ) sv GD 5 EX LEX 5 EX 5 L LEX 5 EX 5 L LEX 5 L t c cT 1 ISC ISC c PR PR PR A + ÷ ÷ ÷ + ÷ = ÷ ¸ ¸ ¸ [m] where LEX L PR ÷ 5 : Pseudorange value corrected for the ionospheric delay and SV clock offset LEX L PR PR , 5 : Pseudorange values observed using two signals (L5 and LEX) (In the case of the L5 signal, either the L5I signal or the L5Q signal) 2 5 115 125 | . | \ | = EX ¸ : Square of the ratio of the LEX to L5 signal frequencies sv t A : Time offset with respect to QZSST including relativistic effect r t A : Relativistic effect correction indicated in Section 6.3.2 c : Speed of light indicated in Section 6.1.1 (iv) Dual-Signal Users of L1C and LEX Signals User receivers calculating range using measurements of the L1C and LEX signals should use the following equation to correct the ionospheric delay. ( ) ( ) sv GD EX 1 C 1 L EX 1 LEX C 1 L EX 1 LEX C 1 L LEX t c cT 1 ISC ISC c PR PR PR A + ÷ ÷ ÷ + ÷ = ÷ ¸ ¸ ¸ [m] where C 1 L LEX PR ÷ : Pseudorange value corrected for the ionospheric delay and SV clock offset LEX C 1 L PR , PR : Pseudorange values observed using two signals (L1C and LEX) (In the case of the L1C signal, either the L1CP signal or the L1CD signal) 2 EX 1 125 154 | . | \ | = ¸ : Square of the ratio of the L1C to LEX signal frequencies sv t A : Time offset with respect to QZSST including relativistic effect r t A : Relativistic effect correction indicated in Section 6.3.2 c : Speed of light indicated in Section 6.1.1 IS-QZSS Ver. 1.4 153 Table 5.7.2-3 Definition of SV clock and group delay parameters for Navigational Message D LEX navigation messages Parameter No. of Bits Scale Factor （LSB） Units 0 f A SV clock bias correction coefficient 26 * 2 -35 s 1 f A SV clock drift correction coefficient 20 * 2 -48 s/s T GD 13 * 2 -35 s ISC L1C/A （Zero “0” in the case of QZS） 13 * 2 -35 s ISC L2C 13 * 2 -35 s ISC L5I5 13 * 2 -35 ISC L5Q5 13 * 2 -35 s ISC L1CP 13 * 2 -35 s ISC L1CD 13 * 2 -35 s ISC LEX 13 * 2 -35 s * Parameters so indicated are in two’s complement notation. 5.7.2.2.1.3 Content of Message Type 11 (ionospheric correction packet) (1) Ionospheric Correction Parameter Packet The ionospheric correction parameter packet is made up of 212 bits, as shown in Figure 5.7.2-7. (2) Properties of Ionospheric Correction Parameter The properties of the ionospheric correction parameter for message type 11 (number of bit, LSB scale factor and units) are in accordance with Table 5.7.2-4. When the ionospheric delay correction standard time is set to all 1’s ("11111111111111111111"), it indicates that the packet does not contain an ionospheric delay correction parameter. In such cases, the remaining data bits of that packet will consist of alternating "1" and "0" values starting with 1. The ionospheric delay correction parameter should only be used during the valid time (T SPAN ) starting from the time expressed by the ionospheric delay correction standard Week Number (WN IONO ) and the ionospheric delay correction standard time (T IONO ). The ionospheric delay correction parameter should be used only when the user receiver latitude and longitude are within the domain indicated in Figure 4.1.5-1 of Section 4.1.5. IS-QZSS Ver. 1.4 154 Table 5.7.2-4 Definition of ionospheric correction parameters for LEX navigation messages Parameter No. of Bits Scale Factor （LSB） Units ｔ IONO Reference time of week for ionospheric correction 20 1 seconds WN IONO Reference Week Number for ionospheric correction 13 1 weeks T SPAN Valid time 8 1 minute φ 0 Latitude coordinates of the origin of approximate function 19 * 0.00001 radian λ 0 Longitude coordinates of the origin of approximate function 20 * 0.00001 radian E 00 Coefficient of approximate function 0－0 degree (latitude－longitude) 22 * 0.001 m E 10 Coefficient of approximate function 1－0 degree (latitude－longitude) 22 * 0.01 m/radian E 20 Coefficient of approximate function 2－0 degree (latitude－longitude) 22 * 0.01 m/radian 2 E 01 Coefficient of approximate function 0－1 degree (latitude－longitude) 22 * 0.01 m/radian E 11 Coefficient of approximate function 1－1 degree (latitude－longitude) 22 * 0.01 m/radian 2 E 21 Coefficient of approximate function 2－1 degree (latitude－longitude) 22 * 0.1 m/radian 3 * Parameters so indicated are in two’s complement notation. IS-QZSS Ver. 1.4 155 1 21 34 42 51 61 81 101 103 125 147 151 169 191 201 WN IONO 13 Bits T SPAN 8 Bits φ 0 9 MSBs λ 0 20 Bits E 00 20 MSBs t IONO 20 Bits E 21 10 MSBs φ 0 10 LSBs E 21 12 LSBs E 01 18 LSBs E 11 22 Bits E 01 4 MSBs E 10 22 Bits E 20 22 Bits DIRECTION OF DATA FLOW FROM SV 50 Bits DIRECTION OF DATA FLOW FROM SV 50 Bits DIRECTION OF DATA FLOW FROM SV 50 Bits DIRECTION OF DATA FLOW FROM SV 50 Bits DIRECTION OF DATA FLOW FROM SV 12 Bits E 00 - 2 LSBs Figure 5.7.2-7 Ionospheric Correction Packet Content IS-QZSS Ver. 1.4 156 (3) User Algorithm for Ionospheric Correction User receivers calculating range using measurements of only one signal should correct the ionospheric delay using the following ionospheric model. Satellite transmission parameters 0 0 , ì | : Latitude and longitude of the origin of approximate function in the coordinate system defined in Section 3.1.4.2 [rad] nm E : Approximate function coefficient Receiver generation parameters El : Elevation angle between user receiver and satellite [rad] Az : Azimuth angle between user receiver and satellite [rad] r | : Latitude of user receiver in the coordinate system defined in Section 3.1.4.2 [rad] r ì : Longitude of user receiver in the coordinate system defined in Section 3.1.4.2 [rad] Constants a: Equatorial radius of the Earth in the coordinate system defined in Section 3.1.4.2 a = in accordance with Section 6.2.2.1.4 [m] iono H : Height of ionospheric shell above the Earth 000 , 350 = iono H [m] Lx ¸ : Square of ratio of Lx frequency (x = 2, 5, EX) to L1 frequency 2 2 5 2 2 1 125 154 , 115 154 , 120 154 , 1 | . | \ | = | . | \ | = | . | \ | = = LEX L L L ¸ ¸ ¸ ¸ [-] Calculation parameters ( ) Lx iono t T ) ( : Diagonal ionospheric delay of frequency LX (X = 1, 2, 5, EX) ) (t F : Inclination factor ) (t pp | : Pierce point latitude in the coordinate system defined in Section 3.1.4.2 ) (t pp ì : Pierce point longitude in the coordinate system defined in Section 3.1.4.2 ) (t pp ¢ : Angle formed by pierce point-earth's center-user receiver [rad] Computational expressions - ( ) Lx iono t T ) ( : Diagonal ionospheric delay of frequency X ( ) m pp n pp n m nm Lx Lx iono t t E t F t T ) ) ( ( ) ) ( ( ) ( ) ( 0 0 2 0 1 0 ì ì | | ¸ ÷ ÷ = ¿¿ = = [m] - ( ) t F : Inclination factor ( ) ( ) 2 cos 1 1 | | . | \ | + ÷ = iono H a t El a t F [-] - ) (t pp | : Pierce point latitude ( ) ( ) ( ) ( ) { } t Az t t t pp r pp r pp cos sin cos cos sin sin 1 ¢ | ¢ | | + = ÷ [rad] - ) (t pp ì : Pierce point longitude IS-QZSS Ver. 1.4 157 ( ) ( ) ( ) | | . | \ | ÷ + = ÷ r pp r pp pp r pp t Az t t t Az t t | ¢ | ¢ ¢ ì ì sin ) ( cos ) ( sin cos ) ( cos sin sin tan 1 [rad] - ) (t pp ¢ : Angle formed by pierce point-earth's center-user receiver | | . | \ | · + ÷ ÷ = ÷ ) ( cos sin ) ( 2 ) ( 1 t El H a a t El t iono pp t ¢ [rad] 5.7.2.2.1.4 Broadcast Period, Updating Period and Valid Time (1) Broadcast Period The sequence for broadcasting message types 10 and 11 is arbitrary under the condition as shown in Table 5.7.2-5. (2) Updating Period Table 5.7.2-5 shows the nominal updating periods for the messages parameters included in message types 10 and 11. (3) Validity Time Table 5.7.2-5 shows the nominal valid time for the messages included in message types 10 and 11. Table 5.7.2-5 Message type 10,11：broadcast interval, update interval and valid time Message data Nominal broadcast interval Nominal update interval Nominal valid time Signal health 1 second 1 seconds - Ephemeris 12 seconds 3 minutes 6 minutes SV clock 12 seconds 3 minutes 6 minutes Ionospheric correction 12 seconds 30 minutes - IS-QZSS Ver. 1.4 158 5.7.2.2.2 Message Types 20 Message type 20 is to be used for the experiment conducted by Geographical Survey Institute （GSI）. (1) Record structure The record structure of message type 20 is shown in Table 5.7.2-6. A record is divided consecutively into every 1,695 bits as 1 packet. Every packet is transmitted in every second. In the case that the end of record appears in the middle of a packet, the value of the rest of the packet is indefinite. One packet shall not contain two or more records. The alert flag defined in Section 5.7.2.1.4 is used for identifying the first packet of the record. Table 5.7.2-6 The Record Structure of Message Type 20 ＃ Name Data Type Data Size Content possible range Assigned Value １ Compression Type uint2 2bits Type of compression applied for the parameter part 0～3 0=no compression 1=zip compression 2～3=undefined ２ Length of Parameter Part uint14 14bits Data length of parameter part in bytes (N) 0～16,383 ３ Parameter Part char*N N*8bits Augmentation parameters of one of the four types in original or compressed form. See (3)～(6) for the detail of each parameter type. ４ CRC char*3 24bits CRC-24Q Total (5+N)*8 bits ＊The “CRC", #4 in Table 5.7.2-6, is calculated for (3+N)×8 [bits] composed of #1, “Compression Type”, with adding fixed “11010011" (8[bits]) on top, #2 “Length of Parameter Part”, and #3, “Parameter Part”. “#CRC-24Q” is a 24-bit CRC: the generator polynomial, G(X), is expressed as follows. ( ) 1 3 4 5 6 7 10 11 14 17 18 23 24 + + + + + + + + + + + + + = X X X X X X X X X X X X X X G (2) Parameter-type ID Table 5.7.2-7 shows contents of four defined Parameter-type IDs. Table 5.7.2-7 Parameter-type ID Parameter-type ID Contents Note 0 Observation information of the reference stations See Table 5.7.2-8 1 Satellite orbit & clock correction information, ionosphere grid interval information See Table 5.7.2-11 2 Tropospheric delay correction information See Table 5.7.2-12 3 Ionospheric delay correction information See Table 5.7.2-13 IS-QZSS Ver. 1.4 159 (3) Observation information of the reference stations Table 5.7.2-8 Observation Information of the Reference Stations Observation information of the reference stations（Parameter-type ID=0） ＃ Name Data Type Data Size Possible range Assigned value Remarks １ Parameter-type ID uint4 4 bits 0～15 0 ２ Area number Indicator uint4 4 bits 0～15 No. of Areas－１ 11 for 12 area setting #3～15 are repeated for each Area（1～No. of areas） ３ Area ID uint4 4 bits 0～15 1～12 ４ Reference Station ID in each Area uint2 2 bits 0～3 0～1 ５ GPS Epoch Time uint30 30 bits 0～604,799,999 Resolution：1msec In Time of Week DF004 ６ No. of GPS Satellites （N SV ） uint5 5 bits 0～31 DF006 ７ GPS Divergence-free Smoothing Indicator bit(1) 1 bits 0,1 Divergence-free Smoothing 0 = not used 1 = used DF007 ８ GPS Smoothing Interval bit(3) 3 bits 0～7 See Table 5.7.2-9 DF008 Total of #3～#8 45 bits #9～15 are repeated for each satellite（1～N SV ） ９ GPS Satellite ID uint6 6 bits 0～63 1～32(PRN number for GPS) １０ GPS L1 Code Indicator bit(1) 1 bits 0,1 0 = C/A Code 1 = P(Y) Code Direct DF010 １１ GPS L1 Pseudorange uint24 24 bits 0～14,989,623 (0～299,792.46m) Resolution：0.02m Residue modulo 299,792.458m DF011 １２ GPS L1 Phase Range－L1 Pseudorange int20 20 bits －524,288 ～524,287 (－262.1440 ～262.1435m) Resolution：0.0005m At start up and after each cycle slip, the initial ambiguity is reset and chosen so that the L1 Phase Range should match the L1 Pseudorange as closely as possible (i.e., the value of GPS L1 Phase Range – L1 Pseudorange is to be close to 0.) If the GPS L1 Phase Range –L1 Pseudorange diverges over time across the range limits defined, the computed value needs to be adjusted (rolled over) by the equivalent of 1500 cycles in order to bring the value back within the defined range in the left column. DF012 １３ GPS L1 Lock time Indicator uint7 7 bits 0～127 See Table 5.7.2-10 DF013 １４ GPS L1 Pseudorange Modulus Ambiguity uint8 8 bits 0～255 (0～ 76,447,076.790m) Resolution：299,792.458m DF014 １５ GPS L1 CNR uint8 8 bits 0～255 (0～63.75dB-Hz) Resolution：0.25dB-Hz DF015 - Total of #9～#15 74 bits Total（All） 8+N Ａ *(45+N SV *74) bits For #9, “GPS Satellite ID”, value from “1” to “32” is assigned to the satellite’s GPS PRN number, and the other values are not used. IS-QZSS Ver. 1.4 160 Content and format of some of the items follows RTCM standards version 3.0. A notation that starts with “DF” in the column “Remarks” indicates the corresponding Data Field in the documentation of RTCM version 3.0. Table 5.7.2-9 GPS Smoothing Interval Indicator Smoothing Interval 000 (0) No smoothing applied 001 (1) ＜30 sec 010 (2) 30-60 sec 011 (3) 1-2 min 100 (4) 2-4 min 101 (5) 4-8 min 110 (6) ＞8 min 111 (7) Unlimited smoothing interval Table 5.7.2-10 GPS L1 Lock time Indicator Indicator(i) Minimum Lock Time (in seconds) Range of Indicated Lock Times (in seconds) 1～23 i 1≦lock time＜24 24～47 i *2-24 24≦lock time＜72 48～71 i *4-120 72≦lock time＜168 72～95 i *8-408 168≦lock time＜360 96～119 i *16-1,176 360≦lock time＜744 120～126 i *32-3,096 744≦lock time＜937 127 lock time≧937 If a cycle slip occurs during the previous measurement cycle, the lock indicator will be reset to zero. IS-QZSS Ver. 1.4 161 (4) Satellite Orbit and Clock correction Information ＋ Ionosphere Grid Interval Information Table 5.7.2-11 Satellite Orbit and Clock Correction Information ＋ Ionosphere Grid Interval Information Satellite Orbit and Clock Correction Information ＋ Ionosphere Grid Interval Information（Parameter-type ID=1） ＃ Name Data Type Data Size Content Possible range Assigned value １ Parameter-type ID uint4 4 bits 0～15 1 ２ DOY uint9 9 bits Day of year in days 0～366 ３ TOD uint7 7 bits Time of day on the initial orbit epoch 0～95 (0～1425 min) Resolution： 15min ４ Version uint12 12 bits Version of auxiliary information used to generate correction parameters 0～4095 ５ Grid interval in Latitude uint4 4 bits Latitudinal grid interval of ionospheric correction model 1～15 (0.05～0.75deg) Resolution： 0.05deg ６ Grid interval in Longitude uint4 4 bits Longitudinal grid interval of ionospheric correction model ditto Ditto ７ No. of Orbit Epochs (N ＯＲＢ ) uint4 4 bits Number of Satellite orbit epochs 0～15 13 ８ No. of Satellites (N ＳＶ ) uint5 5 bits Number of Satellites 0～31 #9～14 are repeated for each satellite (1～N ＳＶ ) ９ Satellite ID uint6 6 bits Satellite ID (PRN number for GPS) 0～63 1～32(GPS) １０ Satellite Health status uint1 1 bits Satellite Health status 0,1 0=Unhealthy 1=Good #11～14 are repeated for each orbit epoch (1～N ＯＲＢ ) １１ Satellite Position Ｘ int37 37 bits Satellite position X-coordinate －68,719,476,736 ～68,719,476,735 Resolution：1mm １２ Satellite Position Ｙ int37 37 bits Satellite position Y-coordinate －68,719,476,736 ～68,719,476,735 Resolution：1mm １３ Satellite Position Ｚ int37 37 bits Satellite position Z-coordinate －68,719,476,736 ～68,719,476,735 Resolution：1mm １４ Satellite Clock offset int31 31 bits Satellite clock offset －1,073,741,824 ～1,073,741,823 (－1,073.741824 ～1,073.741823μsec) Resolution：10 －6 μsec Total 49+N ＳＶ *{7+N ＯＲＢ *(37+37+37+31)} bits IS-QZSS Ver. 1.4 162 (5) Tropospheric Delay Correction Information Table 5.7.2-12 Tropospheric Delay Correction Information Tropospheric Delay Correction Information（Parameter-type ID=2） ＃ Name Data Type Data Size Content Possible Range Assigned value １ Parameter-type ID int4 4 bits 0～15 2 ２ TOW uint20 20 bits GPS Epoch Time (Time of Week) 0～604,799 Resolution ：1sec ３ No. of GPS-Based Control Stations （N ＳＴＮ ) uint11 11 bits Number of GPS-based control stations 0～2,047 N ＳＴＮ ：～1200 #4～5 are repeated for each GPS-based control station （1～N ＳＴＮ ) ４ GPS-Based Control Station ID uint11 11 bits GPS-based control station ID 0～2,047 ５ Zenith Wet Delay uint11 11 bits Zenith wet delay in mm 0～2,047 Total 35+N ＳＴＮ *(11+11) bits (6) Ionospheric Delay Correction Information Table 5.7.2-13 Ionospheric Delay Correction Information Ionospheric Delay Correction Information（Parameter-type ID=3） ＃ Name Data Type Data Size Content Possible range Assigned value １ Parameter-type ID Uint4 4 bits 0～15 3 ２ Area ID Uint4 4 bits Area ID 0～15 1～12 ３ TOW Uint20 20 bits GPS Epoch time (Time of Week) 0～604,799 Resolution： 1sec ４ No. of grid maps Uint5 5 bits Number of grid maps （= Number of satellites） 0～31 #5～10 are repeated for each grid map （k=1～number of grid maps） ５ Satellite ID Uint6 6 bits Satellite ID 0～63 1～32(GPS) ６ Lowest latitude int12 12 bits Northern latitude of the first row ±1,800 (±90deg) Resolution: 0.05deg ７ No. of Rows （Lk） Uint8 8 bits Total number of rows in the k-th grid map（Lk） 0～255 #8～10 are repeated for each row （i=1～Lk） ８ Lowest longitude int13 13 bits Eastern longitude of the first grid point in the row ±3,600 (±180deg) Resolution: 0.05deg ９ No. of grid points （Mk,i） uint8 8 bits Total number of grid points (Mk,i） in the i-th row of the k-th grid map 0～255 #10 is a repeated for each grid point （j=1～Mk,i） １０ VTEC uint14 14 bits VTEC (total electron content of zenith direction) value at a grid point (i,j) 0～16,383 (0～163.82 TECU. If 16,383, it indicates anomalous Value) Resolution: 0.01TECU Total ¿ ¿ | . | \ | × + × + + k i i k k M L , 14 21 26 33 bits for one area IS-QZSS Ver. 1.4 163 5.7.2.2.3 Message Types 21 - 155 Message types 21-155 are for general public user testing by entities. Test personnel may store 1,695 bits of arbitrarily created data in the data section of message types 21-155. However, when message types 10, 11 (for JAXA testing), message type 20 (for GSI testing) or message type 156-255 (for application demonstration in private sector) are being broadcast, message types 21-155 will not be broadcast. 5.7.2.2.4 Message Types 156-255 Message types 156-255 are for application demonstration in private sector. The contents of data are described in Applicable document (6). Satellite Positioning Research and Application Center manages usage of message types 156-255 IS-QZSS Ver. 1.4 164 6 User Algorithms 6.1 Constants 6.1.1 Speed of Light Same as Section 20.3.3.3.3.1 in Applicable Document (1). Expressed using a small letter "c". The value is ] / [ 299792458 s m c = . 6.1.2 Angular Velocity of the Earth's Rotation Same as Table 20-IV in Applicable Document (1). Expressed using the Greek symbol " e O  ". The value is ] / [ 10 2921151467 . 7 5 s rad e ÷ × = O  . 6.1.3 Earth's Gravitational Constant Same as Table 20-IV in Applicable Document (1). Expressed using the Greek symbol " µ ". The value is ] / [ 10 986005 . 3 2 3 14 s m × = µ . 6.1.4 Circular Constant Same as Section 20.3.3.4.3.2 in Applicable Document (1). Expressed using the Greek symbol " t ". The value is 898 1415926535 . 3 = t . 6.1.5 Semi-Circle Same as in Applicable Document (1). Expressed as the circular constant "t " in Section 6.1.4. 6.2 User algorithms relating to time systems and coordinate systems 6.2.1 User algorithms relating to time systems QZSS is based on the following time relationships. (a) Each satellite is operated in accordance with its own SV clock. (b) All time relationship data (TOW) are generated by the SV clock. (c) All other data in navigation messages are relative to GPS time. (d) Navigational messages are transmitted with reference to the SV clock. IS-QZSS Ver. 1.4 165 6.2.2 User Algorithms relating to Coordinate Systems 6.2.2.1 Earth-Centered, Earth-Fixed (ECEF) Coordinate System Constant The Earth-Centered, Earth-Fixed (ECEF) coordinate system referred to in this document is defined as follows. (a) Origin: Earth's center of mass (b) Z-axis: International Earth Rotation and Reference Systems Service (IERS) pole direction (c) X-axis: Direction of intersection of IERS Reference Meridian (IRM) and the plane containing the origin and the Z-axis (d) Y-axis: Direction formed by the right-hand fixed geocentric coordinate system 6.2.2.1.1 QZSS Earth-Centered, Earth-Fixed (ECEF) Coordinate System The Earth-Centered, Earth-Fixed (ECEF) coordinate system used by QZSS is known as the Japan satellite navigation Geodetic System (JGS). It is defined in Section 3.1.4.2. 6.2.2.1.2 Relationship between GPS Earth-Centered, Earth-Fixed (ECEF) coordinate system and QZSS ECEF coordinate system The GPS Earth-Centered, Earth-Fixed (ECEF) coordinate system is known as the World Geodetic System 1984 (WGS84). It is defined Section 20.4.3.3.1 in Applicable Document (1). The relationship between WGS84 and JGS is covered in Section 3.2.2. 6.2.2.1.3 Differences in JGS and WGS84 ellipsoids and the effect of these differences JGS uses the Geodetic Reference System 1980 (GRS80) ellipsoid, while WGS84 uses the WGS84 ellipsoid. The differences between these ellipsoids affect primarily the angle of elevation calculation that must be performed in the process of calculating the ionospheric delay correction. However, as these two ellipsoids are virtually identical, in practical terms there is no difference. (a) GRS80 ellipsoid a = 6,378,137 m f = 1/298.257222101 (b) WGS84 ellipsoid a = 6,378,137 m f = 1/298.257223563 6.2.2.2 Satellite position as determined by orbit calculations The positions of the satellites in each system as determined in Section 6.3.5 indicate the antenna phase center position in the Earth-Centered, Earth-Fixed (ECEF) coordinate system defined by each system as noted in Section 6.2.2.1. IS-QZSS Ver. 1.4 166 6.3 Common GNSS Algorithms 6.3.1 Time Relationships 6.3.1.1 Value Calculated using Time Many parameters relating to satellite status change over time. These parameters are time functions that have coefficients in the navigation messages and are calculated by the user. Calculations are a function of the difference in epoch between the current time and each of the parameters. These parameters include the following: (a) SV clock correction (Section 6.3.2) (b) Satellite orbit calculation k k k k k k k k k i r u v E M t O u , , , , , , , , (Section 6.3.5 and 6.3.6) (c) UTC (Section 6.3.7) 6.3.1.2 Epoch Set at Master Control Station In general, these epochs are established by the Master Control Station (MCS) as follows. (1) oe t : Ephemeris data epoch The minimum update period for Ephemeris data is one hour. The curve fit interval is two hours. The epoch is set near the center of the curve fit interval. Even if the updating period and the curve fit interval are extended, this relationship (of the epoch being set near the middle of the curve fit interval) will be maintained. (2) oc t : SV clock parameter epoch The minimum update period for SV clock parameters is 900 seconds. The curve fit interval is 1800 seconds. The epoch is the same as the epoch for the Ephemeris data that are transmitted at the same time. Even if the updating period and the curve fit interval are extended, this relationship (of the epoch being the same as that of the Ephemeris data) will be maintained. (3) oa t : Almanac data epoch The minimum update period for Almanac data is approximately 3.5 days. The epoch is set near the center of the curve fit interval. Even if the updating period and the curve fit interval are extended, this relationship (of the epoch being set near the middle of the curve fit interval) will be maintained. (4) ot t : UTC parameter epoch The minimum update period for UTC parameters is six days. 6.3.1.3 Consideration for Week Overlap on the Part of the User Same as in Applicable Documents (1), (2) and (3). When implementing the user algorithms in Sections 6.3.2, 6.3.5, 6.3.6, etc., when it is necessary to determine the interval, (t interval = t - t 0 ), between the current time, t, and the epoch time, t 0 , the week beginning/end overlap should be taken into account using the following equations: (a) When ] [ 302400 s t t o > ÷ : ] [ 604800 s t t t o interval ÷ ÷ = (b) When ] [ 302400 s t t o ÷ s ÷ : ] [ 604800 s t t t o interval + ÷ = (c) At all other times: o interval t t t ÷ = IS-QZSS Ver. 1.4 167 6.3.2 User Algorithm for SV Clock Offset In general, the SV Clock Offset algorithm is the same as in Applicable Documents (1), (2) and (3). However, the following points differ from the algorithms specified for GPS alone. The QZS orbit time is estimated and predicted using the LC pseudorange derived from the ionospheric delay-free linear combination (LC) of the L1C/A signal and the L2C signal. The estimation is referenced to the LC antenna phase center of the QZS L-band transmit antenna (L-ANT). This algorithm is used when determining the offset between (a) the LC-SV clock, t sv , estimated and predicted at the LC antenna phase center, and (b) GPST. Single- and dual-frequency-signal users should perform the SV clock corrections corresponding to each QZS signal as noted in this item and in Sections 6.3.3 and 6.3.4. The series of equations in (1) and (2) below are simultaneous equations, (i.e., to determine t, it is necessary to determine ( ) t t sv A and ( ) t t r A using t). However, the values are less than 1 ms, so the sensitivity of ( ) t t sv A and ( ) t t r A with respect to t can be ignored. ( ) ( ) ( ) t t t t t t t t t r c sv sv sv A ÷ A ÷ = A ÷ = where t: GPST ( ) t t sv : Estimated time when the QZS signal was transmitted from the LC antenna phase center ( ) t t sv A : ( ) t t sv time offset with respect to GPST ( ) t t c A : ( ) t t sv time offset of the onboard clock with respect to GPST ( ) t t r A : ( ) t t sv time offset (due only to relativistic effects) with respect to GPST (1) LC-SV Clock Offset at LC Antenna Phase Center The time offset ( ) t t c A of ( ) t t sv with respect to GPST, not including relativistic effects, is expressed as follows: ( ) ( ) ( ) 2 2 1 0 oc f oc f f c t t a t t a a t t ÷ + ÷ + = A where t: GPST oc t : Epoch of SV clock parameter. This is provided in Subframe 1 in the case of the L1C/A signal, in Message Types 30, 31, 32, 33, 34, 35 and 37 in the case of the L2C and L5 signals, and in Subframe 2 in the case of the L1C signal. 2 1 0 , , f f f a a a : SV clock parameters. These are provided in Subframe 1 in the case of the L1C/A signal, in Message Types 30, 31, 32, 33, 34, 35, and 37 in the case of the L2C and L5 signals, and in Subframe 2 in the case of the L1C signal. IS-QZSS Ver. 1.4 168 (2) Relativistic Effect Correction at LC-SV Clock Offset The time offset ( ) t t r A of ( ) t t sv with respect to GPST due to the relativistic effect is expressed as follows: ( ) ( ) ( ) ( ) 2 2 sin c t V t P t E A Fe t t k r · ÷ = = A where 2 2 c F µ ÷ = : Constant, determined from the constants shown in Section 6.1.1 and Section 6.1.2. A e, : Provided in Subframes 2 and 3 in the case of the L1C/A signal, in Message Types 10 and 11 in the case of the L2C and L5 signals, and in Subframe 2 in the case of the L1C signal. ( ) t E k : Eccentric anomaly at t on the GPST time scale. Determined in accordance with Section 6.3.5. ( ) ( ) t V t P , : QZS position and velocity at t on the GPST time scale. Determined in accordance with Section 6.3.5. This is the same value for both the coordinate system in Section 6.2.2.1 and the geocentric inertial coordinate system. 6.3.3 Ionospheric Delay Correction for Dual Frequency Users 6.3.3.1 For L1C/A and L2C Dual Frequency Users L1C/A and L2C dual frequency users should correct the ionospheric delay using the following equation: ( ) ( ) ( ) ( ) ( ) ( ) sv GD 12 A / C 1 L 12 C 2 L L1C/A 12 L2C 12 L1C/A sv L1C/A 12 L2C sv L2C A / C 1 L C 2 L t c cT 1 ISC ISC c PR PR 1 t c PR t c PR PR A + ÷ ÷ ÷ + ÷ = ÷ A + ÷ A + = ÷ ¸ ¸ ¸ ¸ ¸ A / C 1 L C 2 L PR ÷ : Pseudorange corrected using the ionospheric delay and the SV clock parameters L2C L1C/A PR PR , : Pseudorange measured using the signal indicated by the subscript 2 120 154 | . | \ | = 12 ¸ : Square of the ratio between the two signal frequencies c: Speed of light as indicated in Section 6.1.1 IS-QZSS Ver. 1.4 169 6.3.3.2 For L1C/A and L5 Dual Frequency Users L1C/A and L5 dual frequency users should correct the ionospheric delay using the following equation: ( ) ( ) ( ) ( ) ( ) ( ) sv GD 15 L1C/A 15 L5I5 L1C/A 15 L5I5 15 L1C/A sv L1C/A 15 L5I5 sv L5I5 L1C/A L5I5 t c cT 1 ISC ISC c PR PR 1 t c PR t c PR PR A + ÷ ÷ ÷ + ÷ = ÷ A + ÷ A + = ÷ ¸ ¸ ¸ ¸ ¸ ( ) ( ) sv GD 15 L1C/A 15 L5Q5 L1C/A 15 L5Q5 L1C/A L5Q5 t c cT 1 ISC ISC c PR PR PR A + ÷ ÷ ÷ + ÷ = ÷ ¸ ¸ ¸ where A C L Q L A C L I L PR PR / 1 5 5 / 1 5 5 , ÷ ÷ : Pseudorange corrected using the signals indicated by the subscripts using ionospheric delay and SV clock correction parameters 5 5 , , Q L L5I5 L1C/A PR PR PR : Pseudorange measured using the signal indicated by the subscript 2 115 154 | . | \ | = 15 ¸ : Square of the ratio between the two signal frequencies c : Speed of light as indicated in Section 6.1.1 6.3.3.3 L2C and L5 Dual Frequency Users L2C and L5 dual frequency users should correct the ionospheric delay using the following equation: ( ) ( ) ( ) ( ) ( ) ( ) sv GD 25 C 2 L 25 L5I5 L2C 25 L5I5 25 L2C sv L2C 25 L5I5 sv L5I5 L2C L5I5 t c cT 1 ISC ISC c PR PR 1 t c PR t c PR PR A + ÷ ÷ ÷ + ÷ = ÷ A + ÷ A + = ÷ ¸ ¸ ¸ ¸ ¸ ( ) ( ) sv GD 25 C 2 L 25 L5Q5 L2C 25 L5Q5 L2C L5Q5 t c cT 1 ISC ISC c PR PR PR A + ÷ ÷ ÷ + ÷ = ÷ ¸ ¸ ¸ where C L Q L C L I L PR PR 2 5 5 2 5 5 , ÷ ÷ : Pseudorange corrected using the signals indicated by the subscripts using ionospheric delay and SV clock correction parameters 5 5 5 5 2 , , Q L I L C L PR PR PR : Pseudorange measured using the signal indicated by the subscript 2 25 2 12 115 120 , 115 154 | . | \ | = | . | \ | = ¸ ¸ : Square of the ratio between the two signal frequencies c : Speed of light as indicated in Section 6.1.1 IS-QZSS Ver. 1.4 170 6.3.3.4 L1C and L2C Dual Frequency Users L1C and L2C dual frequency users should correct the ionospheric delay using the following equation. ( ) ( ) ( ) ( ) ( ) ( ) sv GD 12 L1C 12 C 2 L L1C 12 L2C 12 L1C sv L1C 12 L2C sv L2C L1C L2C t c cT 1 ISC ISC c PR PR 1 t c PR t c PR PR A + ÷ ÷ ÷ + ÷ = ÷ A + ÷ A + = ÷ ¸ ¸ ¸ ¸ ¸ where C L C L PR 1 2 ÷ : Pseudorange corrected using the signals indicated by the subscripts using ionospheric delay and SV clock correction parameters C L C L PR PR 1 2 , : Pseudorange measured using the signal indicated by the subscript (L1CP signal or L1CD signal in the case of the L1C signal) 2 120 154 | . | \ | = 12 ¸ : Square of the ratio between the two signal frequencies c : Speed of light as indicated in Section 6.1.1 6.3.3.5 L1C and L5 Dual Frequency Users L1C and L5 dual frequency users should correct the ionospheric delay using the following equation: ( ) ( ) ( ) ( ) ( ) ( ) sv GD 15 L1C 15 L5 L1C 15 L5 15 L1C sv L1C 15 L5 sv L5 L1C L5 t c cT 1 ISC ISC c PR PR 1 t c PR t c PR PR A + ÷ ÷ ÷ + ÷ = ÷ A + ÷ A + = ÷ ¸ ¸ ¸ ¸ ¸ C L L PR 1 5÷ : Pseudorange corrected using the signals indicated by the subscripts using ionospheric delay and SV clock correction parameters 5 1 , L C L PR PR : Pseudorange measured using the signal indicated by the subscript (L1CP signal or L1CD signal in the case of the L1C signal; L5I signal or L5Q signal in the case of the L5 signal) 2 115 154 | . | \ | = 15 ¸ : Square of the ratio between the two frequencies c : Speed of light as indicated in Section 6.1.1. IS-QZSS Ver. 1.4 171 6.3.4 Correction of Inter-Signal Group Delay Error by Users of Only One Signal The inter-signal group delay error terms ( GD T , A C L ISC / 1 , CP L ISC 1 , CD L ISC 1 , C L ISC 2 , 5 5I L ISC and 5 5Q L ISC ) are based on the relationship between the L1C/A signal and the L2C signal in accordance with the measurements of the satellite currently under consideration. These terms indicate the difference in inter-group delay error between these signals and the L1CD, L1CP, L2C, L5I and L5Q signals. The standard for sv t A , as shown in Section 6.3.2, is determined based on the LC estimated distance obtained through the ionospheric delay free linear combination using the L1C/A signal and the L2C signal. Accordingly, single frequency users should use the following equation to correct the value: From the definitions for sv t A and GD T , the values of L1C/A ISC in navigation message is as follows: 0 ISC A / C 1 L = 6.3.4.1 Correction of Inter-Signal Group Delay Error for L1C/A Signal ( ) GD sv A / C 1 L GD sv A / C 1 L sv T t ISC T t t ÷ A = + ÷ A = A GD T : Provided by in Subframe 1 6.3.4.2 Correction of Inter-Signal Group Delay Error for L2C Signal ( ) C 2 L GD sv C 2 L sv ISC T t t + ÷ A = A C 2 L GD ISC , T : Provided in Message Type 30 6.3.4.3 Correction of Inter-Signal Group Delay Error for L5 Signal ( ) 5 5 5 5 I L GD sv I L sv ISC T t t + ÷ A = A ( ) 5 5 5 5 Q L GD sv Q L sv ISC T t t + ÷ A = A GD T , 5 5I L ISC , 5 5Q L ISC : Provided in Message Type 30 6.3.4.4 Correction of Inter-Signal Group Delay Error for L1C Signal ( ) CP 1 L GD sv CP 1 L sv ISC T t t + ÷ A = A ( ) CD 1 L GD sv CD 1 L sv ISC T t t + ÷ A = A GD T , L1CP ISC , L1CD ISC : Provided in Subframe 2 IS-QZSS Ver. 1.4 172 6.3.5 Calculation of Satellite Orbit using Ephemeris Data The MCS estimates the QZS orbit in accordance with the virtual LC pseudorange obtained through ionospheric delay-free linear combination using the L1C/A signal and the L2C signal. Based on various QZS models, the MCS propagates the orbit value in its generation of navigation messages. During this process, the LC antenna phase center of the L1C/A and L2C signals is the reference for estimates, predictions and navigation messages. The algorithm for calculations of LC antenna phase center of QZS-1 calculations using Ephemeris Data is as follows: (1) L1C/A signals Positioning Calculation algorithms with Ephemeris data of L1C/A signal is the same as in table 20-IV of Applicable document (1). (2) L1C signals, L2C signals and L5 signals Positioning Calculation algorithms with Ephemeris data of L1C signals, L2C signals and L5 signals are the same as in table 30-II of Applicable document (1) except following point. (You should use the same value with GPS (Ex. the reference value of change rate for right ascension of ascending node ( REF O  )=-2.6×10 -9 [semi-circles/second])). (a) The reference value of Semi-Major Axis A REF =42164200[m] 6.3.6 Calculation of Satellite Orbit and SV Clock Offset using Almanac Data Almanac Data can be used for the rough calculation of predictions for SV clock offset and satellite orbit. 6.3.6.1 Almanac Data (1) L1C/A signal almanac and Midi almanac (L1C, L2C, L5) The algorithm for satellite orbit calculations using L1C/A signal Almanac Data and Midi Almanac Data are the same as the algorithm using Ephemeris Data as noted in Table 20-IV of Section 20.3.3.4.3 of Applicable Document (1), with the following exceptions: (a) Setting to Zero All parameters present in Ephemeris Data and not present in Almanac Data should be set to "0". (b) Calculation of orbit Inclination Angle  In the case of QZSS: ] [ 25 . 0 circle semi i i a ÷ + = o  In the case of GPS: ] [ 3 . 0 circle semi i i a ÷ + = o i a : Actual inclination value i o : Inclination value included in navigation message (c) Calculation of Eccentricity (unique to QZSS)  In the case of QZSS: e a =0.06+e nav  In the case of GPS: e a =0.0+e nav e a : Actual eccentricity value e nav : Eccentricity value included in navigation message IS-QZSS Ver. 1.4 173 (2) Reduced almanac (L1C, L2C and L5 signals) The algorithm for satellite orbit calculations using Reduced Almanac Data is the same as the algorithm using Ephemeris Data as noted in Table 30-II of Applicable Document (1), with the following exceptions: (a) Setting to Zero All parameters present in Ephemeris Data and not present in Almanac Data should be set to "0". (b) Calculation of Semi-Major Axis  For QZSS: A [m] 42,164,200 o + = A  For GPS: A [m] ,559,710 26 o + = A A o : Semi-Major Axis value included in navigation message (c) Eccentricity  For QZSS: e a = 0.075 [-]  For GPS: e a = 0.0 [-] e a : Actual eccentricity value (d) Orbit Inclination Angle  For QZSS: i a = 43 [deg] (= 0.2389 [semi-circles]）  For GPS: i a = 55 [deg] (= 0.3056 [semi-circles]） i a : Actual Inclination Angle (e) Change rate in Right ascension of ascending node (RAAN)  For QZSS: conds] circles/se - [semi 10 7 . 8 10 ÷ × ÷ = O   For GPS: conds] circles/se - [semi 10 6 . 2 9 ÷ × ÷ = O  (f) Argument of Perigee  For QZSS: [deg] 0 27 = e (=－0.5 [semi-circles])  For GPS: [deg] 0 = e (= 0 [semi-circles]) (3) The satellite positioning accuracy resulting from Almanac Data The satellite positioning accuracy resulting from Almanac Data is in accordance with Applicable Document (1) in the case of GPS, and Sections 5.2.2.2.5.2 (2) (a), 5.5.2.2.4.5 and 5.5.2.2.4.6 in the case of QZSS. 6.3.6.2 Almanac Reference Time (t oa ) and Almanac Reference Week Number (WN a ) Note that the Almanac reference time may not be updated even if the Almanac data has been updated. The L1C/A signal differs from GPS as noted in Section 5.2.2.2.5.1 in that the concept of pages does not exist. For this reason, it is impossible to guarantee when Almanac data updating may occur. For more information on the Almanac reference Week Number corresponding to Almanac reference time, see Section 5.2.2.2.5.2(5). 6.3.6.3 Calculation of Satellite SV Clock Offset using Almanac Time Data Almanac time data can be used for the rough calculation of prediction of the SV clock offset. The reduced Almanac is not included in the Almanac time data. Of these, the Almanac time data comprise an 11-bit constant (a f0 ) and an 11-bit (10-bit for the CNAV and CNAV2 message) primary term (a f1 ). These data can be used to determine the satellite time offset with respect to GPS time. The algorithm used to calculate the SV clock offset using Almanac time data is the same as the algorithm using Ephemeris data specified in Section 6.3.2(1), with the following exceptions. IS-QZSS Ver. 1.4 174 (a) Setting to zero Parameter a f2 that is present in Ephemeris data and not present in Almanac data should be set to "0". The SV clock offset accuracy produced by Almanac data is in accordance with Applicable Document (1) in the case of GPS and Section 5.2.2.2.5.2 (2) (a) in the case of QZSS. 6.3.7 Calculation of Coordinated Universal Time (UTC) using the global standard time parameter It is possible to use the UTC parameter to convert system time to coordinated universal time (UTC). In the case of the L1C/A signal, coordinated universal time is UTC (USNO) when the data ID is "00" and UTC (NICT) when the data ID is "11". In the case of the L2C and L5 signals, coordinated universal time is UTC (USNO) in the case of Message Type 49 and UTC (NICT) in the case of Message Type 33. The algorithm is the same as in Section 20.3.3.5.2.4 of Applicable Document (1). 6.3.8 Correction of Ionospheric Delay Using Ionospheric Parameters This is the same as in Section 20.3.3.5.2.5 of Applicable Document (1). Correction can be performed by determining the ionospheric delay, iono cT , for the L1 frequency and subtracting this value from measured pseudorange. The ionospheric delay for the L2 frequency is iono T c 2 120 154 | . | \ | . The ionospheric delay for the LEX frequency is iono T c 2 125 154 | . | \ | . The ionospheric delay for the L5 frequency is iono T c 2 115 154 | . | \ | . 6.3.9 Correction Using NMCT (L1C/A Signal) and DC Data (L1C, L2C and L5 Signals) 6.3.9.1 Correction Using NMCT (Navigation Message Correction Table) Data For the L1C/A signal, the Estimated Range Deviation (ERD) value in the NMCT for each satellite is the estimate of the difference between (a) the measured pseudorange value for each satellite monitored from the ground by QZSS and (b) the value for pseudorange that is calculated based on the Ephemeris data and SV clock parameters for each satellite tracked. ERD is calculated by the MCS. The following equation is used to correct the measured pseudorange value using the ERD value: ERD PR PR M C ÷ = where C PR : Corrected pseudorange value ERD: Estimated range deviation M PR : Measured pseudorange value IS-QZSS Ver. 1.4 175 6.3.9.2 Correction using DC Data (L1C, L2C and L5 Signals) In the L1C, L2C and L5 signals, the DC data for each satellite constitute the estimate of the difference between (a) the measured pseudorange value for each satellite monitored from the ground by the QZSS MCS and (b) the value for estimated pseudorange that is calculated based on the Ephemeris data and SV clock parameters for each satellite tracked. The DC data are calculated by the MCS. 6.3.9.2.1 Use of CDC Data If the satellite DC data pair (EDC and CDC) can be used, the user may use the CDC data in place of the algorithm in Section 6.3.2 (1) to perform the LC-SV clock correction referenced to the LC antenna phase center. In other words, the PRN code phase offset ( ) t t c A of the satellite time with respect to QZSST, with the exception of the relativistic effect, is expressed as follows: ( ) ( ) ( )( ) ( ) 2 2 1 1 0 0 oc f oc f f f f c t t a t t a a a a t t ÷ + ÷ + + + = A o o where t : QZSST defined in Section 3.1.4.1 oc t : Epoch of SV clock parameter, provided in Subframe 1 in the case of the L1C/A signal, in Message Types 30, 31, 32, 33, 34, 35 and 37 in the case of the L2C and L5 signals, and in Subframe 2 in the case of the L1C signal. 2 1 0 , , f f f a a a : SV clock parameters, provided in Subframe 1 in the case of the L1C/A signal, in Message Types 30, 31, 32, 33, 34, 35 and 37 in the case of the L2C and L5 signals, and in Subframe 2 in the case of the L1C signal. 1 0 , f f a a o o : SV clock parameters, provided in Message Types 34 and 13 in the case of the L2C and L5 signals, and in Subframe 3 in the case of the L1C signal. This can only be applied when predict time of week for the Ephemeris Data and the SV Clock Parameters is older than predict time of week of the DC data (in other words, when the value of D op t ÷ is greater than the value of op t ). 6.3.9.2.2 Use of EDC Data If the satellite DC data pair (EDC and CDC) can be used, the user may use the EDC data in place of the algorithm in Section 6.3.5 to calculate the orbit referenced to the LC antenna phase center. This user algorithm is the same as the one in Applicable Document (1). This can only be used when the epoch for the Ephemeris data and the SV clock parameters is older than the epoch of the DC data (in other words, when the value of D op t ÷ is greater than the value of op t ). 6.3.10 User Algorithms Relating to Interoperability with Other Satellite Navigation Systems TBD IS-QZSS Ver. 1.4 176 6.4 L1 SAIF Algorithm 6.4.1 Validity period (Time-out period) User receivers must keep track of the age-of-data corresponding to each L1-SAIF message parameter. The contents of the SAIF messages have various validity periods so-called “time-out period” appropriate to the characteristics of each parameter as shown in Table 6.4.1-1. Any SAIF parameters whose age-of-data exceeds the corresponding validity period must not be used for navigation. The starting point for determination of the age-of-data is the second of the GPS epoch time when the first bit of the preamble for the message including a relevant parameter is transmitted. The validity period is defined in Table 6.4.1-1. Note that the durations of the validity periods not only vary from message type to message type, they also can be different for different parameters within the same message type. In particular, Message types 2-6 and 24 include both the Fast Correction parameter (FC i ) and its accuracy (UDREI i ), and these two parameters have different validity periods. Table 6.4.1-1 Validity Periods for L1-SAIF Message Parameters Message Type ID Contents Timeout period (s) 0 Test mode 60 1 PRN mask 1200 2 – 6, 24 Fast Correction 120 UDREI 12 10 Degradation Parameter 240 18 IGP mask 1200 24, 25 Long-term Correction 240 26 Ionospheric Vertical Delay 600 GIVEI 600 28 Clock-ephemeris Covariance 240 52 TGP mask 600 53 Tropospheric Delay Correction 600 56 Inter signal bias correction data 1200 58 QZS ephemeris 300 6.4.2 Error Correction Algorithm 6.4.2.1 Clock and Orbit error correction (Long-term correction) The Long-term correction message (Message type 24, 25) provides parameters for use in correcting both clock and orbital position errors associated with the corresponding navigation satellite. The clock offset value calculated using the navigation messages transmitted by each GPS or QZS is further corrected as follows using the long-term Clock Error Correction parameter in the SAIF message. i SV i SV corrected i SV t t t , , , A + A = A o (6.4-1) where, i SV t , A o [s] is the Clock Error Correction parameter of the Long-term Correction SAIF message. In addition, the orbital position of the corresponding navigation satellite is corrected as follows using the long-term Orbital Position correction parameters in SAIF message as well. ( ( ( ¸ ( ¸ + ( ( ( ¸ ( ¸ = ( ( ( ¸ ( ¸ i i i ephemeris i i i corrected i i i z y x z y x z y x o o o (6.4-2） where, δx i , δy i and δz i [m] are respectively, the x-, y- and z- Orbital Position Error Correction parameters of the Long-term Correction SAIF message. The satellite clock error correction parameter, δΔt sv,i , at any time of day, t k , is calculated using the following equation. (This parameter is applied to the clock offset calculation in accordance with IS-QZSS Ver. 1.4 177 equation (6.4-1).) ( ) ( ) LT i k f i f i k i SV t t a a t t , 1 , 0 , , ÷ + = A o o o (6.4-3) where ( ) LT i k t t , ÷ is corrected for end of day crossover if necessary. If the velocity code = 0, then the corresponding δa i,f1 term should be set to 0. In cases where the augmented navigation satellite signals are from a different RNSS system, for instance GLONASS, the following equation is to be applied: ( ) ( ) GLONASS i LT i k f i f i k i SV a t t a a t t , , 1 , 0 , , o o o o + ÷ + = A (6.4-4） In this case, the time offset between GPS time and GLONASS, δa i,GLONASS , is provided in message type XXX (TBD). Users must NOT use GLONASS unless the corresponding time offset parameter is received. The appropriate correction value from equation (6.4-3) or (6.4-4) is added to the estimated time, Δt sv , defined in Applicable Document (1). The orbital position of the corresponding navigation satellite is corrected by adding the correction vector calculated in equation (6.4-5) to the estimated position vector (see equation (6.4-2)) received via the broadcast ephemeris data. ( ) LT i k i i i i i i i i i t t z y x z y x z y x , ÷ ( ( ( ¸ ( ¸ + ( ( ( ¸ ( ¸ = ( ( ( ¸ ( ¸    o o o o o o o o o (6.4-5) The above correction vector is applied to the same satellite, i, in ECEF coordinates at time, t k . If the velocity code = 0, then the second term in equation (6.4-5) should be set to 0. Note that the ephemeris data broadcast in the L1-C/A signal, (i.e., NAV message), MUST be used for the corrections calculated in equations (6.4-1) and (6.4-2) using data from the L1-SAIF messages. Ephemeris data provided in the CNAV or CNAV2 messages should NOT be applied to the corrections performed using the L1-SAIF message data. 6.4.2.2 Fast Correction and Atmospheric Delay Correction The error correction parameters broadcast in the SAIF messages are used to correct the pseudorange measurements (between satellite and user receiver). The corrected pseudorange, corrected i PR [m], is used to compute user position after the SAIF correction parameters are applied to the measured pseudorange for each observable satellite, measured i PR [m] using the following equation: i i i measured i corrected i TC IC FC PR PR + + + = (6.4-6） FC i , IC i , and TC i [m] are the Fast Correction, Ionospheric Delay Correction, and Atmospheric Delay Correction parameters, respectively. In advance of applying the ionospheric and atmospheric delay corrections, a rough estimate of user position is required since these delay corrections are dependant upon position. The Fast Correction parameter is mainly used for the correction of satellite onboard clock variation. It can be used to correct clock variations ranging from several seconds to several minutes. The Fast Correction parameter is not a function of user position and its value at any given time will be identical for all users. Note that the ionospheric and atmospheric delay correction parameters are not frequently updated. For a general least-squares position solution, the following projection matrix, S, is used: IS-QZSS Ver. 1.4 178 ( ) W G G W G s s s s s s s s s s s s S N t t t N z z z N y y y N x x x · · · = ( ( ( ( ¸ ( ¸ = ÷ T 1 T , 2 , 1 , , 2 , 1 , , 2 , 1 , , 2 , 1 ,     (6.4-7） where, G is the matrix which represents the relationship between user position and satellite position: ( ( ( ( ¸ ( ¸ ÷ ÷ ÷ ÷ ÷ ÷ ÷ ÷ ÷ = 1 sin cos cos sin cos 1 sin cos cos sin cos 1 sin cos cos sin cos 2 2 2 2 2 1 1 1 1 1 N N N N N EL AZ EL AZ EL EL AZ EL AZ EL EL AZ EL AZ EL G     (6.4-8） where EL i [rad] and AZ i [rad] are the calculated elevation angle and azimuth, respectively, from the user to satellite i. AZ i is the azimuth angle of the satellite measured from North in a clockwise direction. The inverse of the weighting matrix, W, is expressed as below: ( ( ( ( ( ¸ ( ¸ = ÷ 2 2 2 2 1 1 0 0 0 0 0 0 N W o o o      (6.4-9） where oi is the calculated user range error with respect to satellite i. 6.4.2.3 Ionospheric Propagation Delay Correction 6.4.2.3.1 Determination of Pierce Point In order to calculate an ionospheric delay correction, the ionospheric pierce point (IPP), must first be determined. The IPP is defined as the point (in the ionospheric layer) where the line between a satellite and the user receiver intersects the ellipsoidal surface 350 km above the WGS84 ellipsoidal surface. Firstly, the latitude, i pp, | [rad], of the IPP is calculated using following equation: ) ( i i pp u i pp u - i pp AZ cos sin cos cos sin sin , , 1 , ¢ | ¢ | | + = (6.4-10) where, u | [rad] is the latitude of the user receiver, and i pp, ¢ [rad] is the angle: IPP - Earth center - user position, calculated as follows: ( ¸ ( ¸ + ÷ ÷ = ÷ i I e e i i pp EL h R R EL π cos sin 2 1 , ¢ (6.4-11) where ELi [rad] is the elevation angle of satellite; R e [km] is the Earth’s radius; and h I is the approximate altitude of ionospheric layer, assumed to be 350 [km]. Next, the longitude, i pp, ì [rad], of the IPP is calculated using one of the following equations: ( ( ¸ ( ¸ + = AZ λ λ i pp i i pp - u i pp , , 1 , cos sin sin sin | ¢ （6.4-12） where u ì [rad] is the longitude of the user receiver and the other terms are as defined above. IS-QZSS Ver. 1.4 179 6.4.2.3.2 Selection of Ionospheric Grid Points (IGP) The ionospheric delay at an IPP is calculated by interpolation using the ionospheric delay values at surrounding IGPs. The IGPs are selected in accordance with the IGP mask information provided in message type 18, independent of the value of delay and GIVE at each IGP. The selection of the IGPs is implemented with one of the following two procedures: Procedure a): If an IPP is surrounded by four IGPs arranged in a rectangular shape separated by 5 degrees in both latitude and longitude, these surrounding four IGPs are selected for the ionospheric delay correction. Procedure b): If an IPP is not surrounded by four IGPs as defined in Procedure a), but is surrounded by three IGPs arranged in a triangular shape separated by 5 degrees in both latitude and longitude, these surrounding three IGPs are selected for the ionospheric delay correction. In cases where an IPP is not surrounded by four or three IGPs, as required for Procedure a) or b), respectively, the ionospheric delay for that IPP cannot be calculated. Moreover, if any one of the IGPs selected for Procedure a) or b) above is prohibited from use or unmonitored, the ionospheric delay at the corresponding IPP cannot be computed. However, in the case of Procedure a), if only one of the four surrounding IGPs is prohibited from use, then the remaining three valid IGPs can be used with Procedure b). 6.4.2.3.3 Ionospheric Delay Interpolation at Pierce Point The ionospheric delay at the IPP is calculated by interpolation using the delays associated with the four or three IGPs selected using Procedure a) or b), respectively, as described in the previous section. The following equation is to be used for interpolation with four IGPs: ( ) ¿ = = 4 1 , , , , k k k i pp i pp i pp W t ì | t （6.4-13） The vertical delay at the IPP, i pp, t [s], is described as a function of the IPP latitude, i pp, | [rad], and the IPP longitude, i pp, ì [rad]. k t [s] is the vertical delay at IGP k. The weighting coefficient at each IGP is computed using 1 2 1 , 1 2 1 , , | | | | ì ì ÷ ÷ = ÷ ÷ = i pp pp i pp pp y λ λ x as follows: pp pp y x W = 1 （6.4-14） pp pp y x ( W ) 1 2 ÷ = （6.4-15） ) y )( x ( W pp pp ÷ ÷ = 1 1 3 （6.4-16） ) y ( x W pp pp ÷ = 1 4 （6.4-17） The following definitions illustrated in Figure 6.4.2-1 also apply: λ 1 [rad] = longitude of IGPs west of IPP λ 2 [rad] = longitude of IGPs east of IPP φ 1 [rad] = latitude of IGPs south of IPP φ 2 [rad] = latitude of IGPs north of IPP IS-QZSS Ver. 1.4 180 φ 1 φ 2 λ 1 λ 2 x ｙ Δ φ pp ＝φ pp,i －φ 1 Δ λ pp ＝λ pp,i －λ 1 τ pp,i （φ pp,i , λ pp,i ） τ 1 τ 2 τ 4 τ 3 User’s IPP φ 1 φ 2 λ 1 λ 2 x ｙ Δ φ pp ＝φ pp,i －φ 1 Δ λ pp ＝λ pp,i －λ 1 τ pp,i （φ pp,i , λ pp,i ） τ 1 τ 2 τ 4 τ 3 User’s IPP Figure 6.4.2-1 Definition of interpolation with four surrounding IGPs The following equation is to be used for interpolation with three IGPs: ( ) ¿ = = 3 1 , , , , k k k i pp i pp i pp W t ì | t （6.4-18） The weighting coefficient for each IGP is as follows: pp y W = 1 （6.4-19） pp pp y x W ÷ ÷ =1 2 （6.4-20） pp x W = 3 （6.4-21） As illustrated in Fig. 6.4.2-2, the second weighting coefficient, W 2 , must be properly determined from the three IGPs. IS-QZSS Ver. 1.4 181 φ 1 φ 2 λ 1 λ 2 x ｙ Δ φ pp ＝φ pp,i －φ 1 Δ λ pp ＝λ pp,i －λ 1 τ 1 τ 2 τ 3 τ pp,i （φ pp,i , λ pp,i ） User’s IPP φ 1 φ 2 λ 1 λ 2 x ｙ Δ φ pp ＝φ pp,i －φ 1 Δ λ pp ＝λ pp,i －λ 1 τ 1 τ 2 τ 3 τ pp,i （φ pp,i , λ pp,i ） User’s IPP Figure 6.4.2-2 Definition of interpolation with three surrounding IGPs 6.4.2.3.4 Computation of Ionospheric Propagation Delay Correction The slant delay correction value, IC i , is calculated by multiplying the vertical delay at the IPP (as interpolated from the surrounding IGPs), by the obliquity factor, F pp . ( ) i pp i pp i pp i pp i λ τ F IC , , , , ,| · ÷ = （6.4-22） where, 2 1 2 , cos 1 ÷ ( ( ¸ ( ¸ | | . | \ | + ÷ = I e i e i pp h R EL R F （6.4-23） is the obliquity factor which depends upon the elevation angle from the user receiver to the satellite, EL i [rad], the Earth radius R e = 6378.137 [km], and the assumed altitude of the ionospheric layer h I = 350 [km]. 6.4.2.4 Zenith Tropospheric Delay Correction 6.4.2.4.1 Correction based on SAIF Message The message type 53 with TGP block ID n contains ZTDOs at from 34n+1 th to 34(n+1) th TGPs in the same order as in the effective TGP mask data provided by message type 52. 6 bits ZTDO has a resolution of 0.01m in the range of [-0.32, 0.30m]. “011111” indicates that ZTDO has not been provided at the corresponding TGP. IS-QZSS Ver. 1.4 182 By adding the value of Zenith Tropospheric Delay model defined by the following equation 4 at user position to ZTDO at TGP, Zenith Tropospheric Delay at user position will be obtained. Note: Units: mm, Day of Year: doy , Latitude: | [deg], Height above Sea Level: H [m] ( ) ( ) ( ) ( ) 2 4 [ ] 2690 97sin 119 28sin 11 6.5 365.25 365.25 2 4 0.31 0.023sin 63 0.0071sin 13 365.25 365.25 ZTD mm doy doy H doy doy t t | t t | | | | = + ÷ + + ÷ | | \ . \ . | | | | | | + × ÷ + + ÷ + | | | \ . \ . \ . （6.4-24） It is recommended to use ZTDO at a TGP which is within 70km in distance from user. In the case that plural TGPs are available within this range, it is recommended to use the ZTDOs at up to 3 nearest TGPs. From the plural ZTDOs at the plural TGPs, it is possible to obtain one Zenith Tropospheric Delay more suitable for each user position through some interpolation, such as weighted average, etc. As for the weighting function, the following one could be suggested, where x [km] is a distance from TGP. ( ) ( ) 2 1 0.08 10.0 w x x = + （6.4-25） Tropospheric Delay contained in pseudorange is estimated by multiplying Zenith Tropospheric Delay and mapping function. Additive inverse of the obtained Zenith Tropospheric Delay is equivalent to i TC in equation (6.4-6). As for the mapping function, the following equation could be suggested as an example, where EL [rad] is the elevation of satellites. ( ) ( ) EL EL m 2 sin 002001 . 0 001 . 1 + = （6.4-26） i TC in equation (6.4-6) is computed as follows: ¿ ¿ = = ÷ = nT k k nT k k k i i x w ZTD x w EL m TC 1 1 ) ( ) ( ( 　・ ）・　 (6.4-27) Where nT is the number of TGPs for tropospheric correction. 6.4.2.4.2 Correction by the model Tropospheric delay correction may be performed by the model described in Application document (5). 4 There will be possibility to change about detailed numerical value in future. IS-QZSS Ver. 1.4 183 6.4.3 Algorithm for Integrity information Integrity of SAIF message is actually depending on the protection level. It means that the probability which user positioning error of horizontal and vertical direction is beyond the protection level shall be specified integrity risk (1 - integrity) or less to (in) the SIS accuracy that has provided by SAIF message with the signal. 6.4.3.1 Calculation of protection level Horizontal Protection Level（HPL） and Vertical Protection Level（VPL） is calculated as follows. H H d K HPL · = （6.4-27） V V d K VPL · = （6.4-28） Constants are defined by Table 6.4.3-1. “Integrity” in the table means integrity required by the user. IRI is broadcasting via message type 10. See the covariance of positioning error as follows. ¿ = · = N i i i z V s d 1 2 2 , 2 o （6.4-29） 2 2 2 2 2 2 2 2 2 xy y x y x H d d d d d d + | | . | \ | ÷ + + = （6.4-30） Calculate the each with the following value. ¿ = · = N i i i x x s d 1 2 2 , 2 o （6.4-31） ¿ = · = N i i i y y s d 1 2 2 , 2 o （6.4-32） ¿ = · · = N i i i y i x xy s s d 1 2 , , o （6.4-33） Positioning accuracy i o as for Satellite i is determined as follows. 2 , 2 , 2 , 2 , 2 trop i air i UIRE i flt i i o o o o o + + + = （6.4-34） Table 6.4.3-1 Relations of integrity and Constants “K” integrity IRI condition K H K V 1-10 -7 IRI=0 5.63 5.33 1-10 -6 IRI≦1 5.26 4.90 1-10 -5 IRI≦2 4.80 4.42 1-10 -４ IRI≦3 4.29 3.89 1-10 -3 IRI≦4 3.72 3.29 IS-QZSS Ver. 1.4 184 6.4.3.2 Clock and orbit configuration Correction accuracy of fast and long-term correction is calculated as follow. ( ) ¦ ¹ ¦ ´ ¦ = + = + = 1 , 0 , 2 2 2 , 2 , 2 , UDRE ltc UDRE UDRE i UDRE ltc UDRE UDRE i flt i RSS RSS c o o c o o o （6.4-35） As for the long correction degradation, GPS and Geostationary satellite is determined as below. Note that VC is the velocity code contained long-term correction data. | | ¦ ¹ ¦ ´ ¦ = ÷ · = ÷ ÷ ÷ · + = 0 , 1 , , , 0 max 0 _ 0 _ 1 _ , , 1 _ _ VC I t t C VC I t t t t C C v ltc ltc v ltc v ltc LT i LT i v ltc lsb ltc ltc c （6.4-36） Also, QZSS is calculated as follows. | | 1 _ , , 1 _ _ , , 0 max v qzs LT i LT i v qzs lsb qzs ltc I t t t t C C ÷ ÷ ÷ · + = c （6.4-37） 6.4.3.3 Clock―ephemeris covariance Message type 10 and 28 is calculated by equation（6.4-35）の UDRE o | | ariance T T e UDRE C I E E I cov 5 2 + · · · · = ÷ o （6.4-38） Note: “e” is scale coefficient shown in the message type 28. “I” is the vector which contains unit vector that indicates the direction of satellite from receiver. ( ( ( ( ¸ ( ¸ = 1 sin cos cos sin cos i i i i i EL AZ EL AZ EL I （6.4-39） Matrix E is as follows ( ( ( ( ¸ ( ¸ = 4 , 4 4 , 3 3 , 3 4 , 2 3 , 2 2 , 2 4 , 1 3 , 1 2 , 1 1 , 1 0 0 0 0 0 0 E E E E E E E E E E E （6.4-40） 6.4.3.4 Ionospheric Propagation Delay σ 2 UIRE of equation（6.4-34） is calculated as follows. UIVE pp UIRE F 2 2 2 o o · = （6.4-41） σ 2 UIVE is interpolated to the specified IPP with σ 2 GIVE defined at IGPs by user as follows. IS-QZSS Ver. 1.4 185 GIVE n pp pp n n UIVE ,y x W , 2 4 1 2 ) ( o o · = ¿ = （6.4-42） or GIVE n pp pp n n UIVE ,y x W , 2 3 1 2 ) ( o o · = ¿ = （6.4-43） Note: σ 2 GIVE is the dispersion model of Ionospheric vertical delay error at IGP. It can be obtained by GIVEI on table 5.4.3-16. 6.4.3.5 Multipath error As for air i , o that shows multipath error, use the following model. ( ) { } 2 2 , 4 . 0 deg 10 exp 53 . 0 13 . 0 + ÷ + = i air i EL o （6.4-44） 6.4.3.6 Tropospheric Propagation Delay Remained error model of Tropospheric Delay of Satellite i is calculated as follows. ( ) i trop i EL 2 , sin 002 . 0 12 . 0 + = o （6.4-45） 6.4.4 Calculation of QZSS satellite Position The position of QZSS satellite can be calculated by numerical integration with position and velocity given in message type 58. Satellite position is calculated using following equations. x v dt dx = (6.4-46) y v dt dy = (6.4-47) z v dt dz = (6.4-48) According to the velocity, following equations with perturbation of the acceleration given in message type 58 can be used. Q y e e e x X v x x r z r R J r x dt dv     + O + O + | | . | \ | ÷ ÷ ÷ = 2 5 1 2 3 2 2 2 5 2 2 3 µ µ (6.4-49) Q x e e e y Y v y y r z r R J r y dt dv     + O ÷ O + | | . | \ | ÷ ÷ ÷ = 2 5 1 2 3 2 2 2 5 2 2 3 µ µ (6.4-50) Q e z Z z r z r R J r z dt dv   + | | . | \ | ÷ ÷ ÷ = 2 2 5 2 2 3 5 3 2 3 µ µ (6.4-51) Here, 9 2 10 7 . 1082625 ÷ × = J IS-QZSS Ver. 1.4 186 6.5 LEX Algorithm 6.5.1 Reed Solomon Coding/Decoding Algorithm for LEX Navigation Message 6.5.1.1 Construct Galois Field ( ) 8 2 GF We choose ( ) 1 2 7 8 + + + + = x x x x x F as a primitive polynomial of degree 8 over 2 Z . (Note that because this is the binary case, addition (+) is equivalent to exclusive-OR (XOR) and multiplication (x) is equivalent to the logical AND operation.) When o is a root of ( ) 0 = x F , we have the following (note that 8 8 o o = ÷ over 2 Z ): 1 2 7 8 8 + + + = ÷ = o o o o o (6.5-1) From equation (6.5-1), any power of o can be represented by a linear combination of ( ) 1 , , , , , , , 0 1 2 3 4 5 6 7 = o o o o o o o o over 2 Z (note that 0 = + i i o o ）as follows: ( ) ( ) 1 1 1 1 1 1 6 7 254 2 4 7 4 2 7 4 8 9 10 3 7 2 3 2 7 2 3 8 8 9 2 7 8 + + + = + + + = + + + + + = + + = × = + + = + + + + + + = + + + = × = + + + = o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o  　　　　 　　 　　 (6.5-2) Then, the order of o is 255 since: ( ) 0 2 7 2 7 2 7 8 254 255 1 1 o o o o o o o o o o o o o o = = + + + + + + = + + + = × = (6.5-3) From equations (6.5-2), addition of two powers of o is as follows: When 0 0 1 1 6 6 7 7 o o o o o m m m m m u u u u + + + + =  (6.5-4) 0 0 1 1 6 6 7 7 o o o o o n n n n n u u u u + + + + =  (6.5-5) the addition is given by: ( ) ( ) ( ) ( ) l n m n m n m n m n m u u u u u u u u o o o o o o o = + + + + + + + + = + 　 0 0 0 1 1 1 6 6 6 7 7 7  (6.5-6) Each nj mi u u , coefficient is either a zero or a one, and ni mi u u + is the logical “exclusive OR” of the two coefficients. By the above operations, ( ) { } 254 2 1 0 , , , , 1 , 0 o o o o  = makes a Galois Field ( ) 8 2 GF . 6.5.1.2 Change of Basis From equations (6.5-2), one basis for ( ) { } 254 2 1 0 , , , , 1 , 0 o o o o  = over 2 Z is the set { } 0 1 2 3 4 5 6 7 , , , , , , , o o o o o o o o . IS-QZSS Ver. 1.4 187 When 242 7 67 6 184 5 46 4 163 3 226 2 88 1 125 0 , , , , , , , o o o o o o o o = = = = = = = = l l l l l l l l , the set { } 7 6 5 4 3 2 1 0 , , , , , , , l l l l l l l l is another basis for ( ) { } 254 2 1 0 , , , , 1 , 0 o o o o  = over 2 Z . When the nth power of o is represented by two linear combinations: 7 7 6 6 5 5 4 4 3 3 2 2 1 1 0 0 0 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 l z l z l z l z l z l z l z l z u u u u u u u u n + + + + + + + = + + + + + + + = o o o o o o o o o (6.5-7) The relationship between 0 1 2 3 4 5 6 7 , , , , , , , u u u u u u u u and 7 6 5 4 3 2 1 0 , , , , , , , z z z z z z z z is given by the following two equations: ( ) | | | | | | | | | | | . | \ | | | | | | | | | | | | . | \ | = 1 1 0 1 1 1 1 1 1 0 0 1 0 1 0 1 1 1 1 0 0 1 0 1 1 0 0 1 1 1 1 1 0 1 1 0 0 0 1 1 1 1 1 1 1 0 1 1 0 0 0 1 0 1 1 1 0 1 1 1 0 0 0 1 , , , , , , , 0 1 2 3 4 5 6 7 7 6 5 4 3 2 1 0 t u u u u u u u u z z z z z z z z (6.5-8) ( ) | | | | | | | | | | | . | \ | | | | | | | | | | | | . | \ | = 0 0 1 1 0 0 1 1 1 0 0 1 0 0 0 0 0 0 1 1 0 1 0 1 1 1 1 0 1 1 1 1 1 0 1 1 0 1 1 1 0 1 0 0 1 0 1 0 1 1 1 1 0 1 0 0 0 0 1 0 0 0 1 1 , , , , , , , 7 6 5 4 3 2 1 0 0 1 2 3 4 5 6 7 t z z z z z z z z u u u u u u u u (6.5-9) Each j i z u , coefficient is either a zero or a one, and addition for these matrix operations is simply “exclusive OR”. 6.5.1.3 Encoding When the Header and Data parts of the LEX message (see Figure 5.7.2-1） are given, the Reed-Solomon encoding is performed as follows. The target encoded length is 214 symbols (5 to 218) followed by the Preamble. Think of the bits in each symbol as 7 6 5 4 3 2 1 0 , , , , , , , z z z z z z z z , corresponding to the elements of ( ) { } 254 2 1 0 , , , , 1 , 0 o o o o  = (see Section 6.5.1.2). When the binary string 5th,6th, ･･･,218th symbol is represented by 5 A , 6 A , ･･･, 218 A ( ( ) { } 254 2 1 0 , , , , 1 , 0 o o o o  = e i A ), polynomial ( ) x I over ( ) { } 254 2 1 0 , , , , 1 , 0 o o o o  = is defined as follows: ( ) 218 217 212 6 213 5 A x A x A x A x I + + + + =  (6.5-10) IS-QZSS Ver. 1.4 188 If the code generator polynomial over ( ) { } 254 2 1 0 , , , , 1 , 0 o o o o  = is defined as follows: ( ) ( ) [ = ÷ = 143 112 11 j j x x g o (6.5-11) then, ( ) x P is the remainder of dividing ( ) x I x 32 by ( ) x g . Division is used operation of Galois Field ( ) { } 254 2 1 0 , , , , 1 , 0 o o o o  = (see Section 6.5.1.1). ( ) x P is written as follows: ( ) 32 31 30 2 31 1 B x B x B x B x P + + + + =  (6.5-12) ( ) { } 254 2 1 0 , , , , 1 , 0 o o o o  = e i B When each i B is represented by a linear combination of set { } 7 6 5 4 3 2 1 0 , , , , , , , l l l l l l l l : 7 7 6 6 5 5 4 4 3 3 2 2 1 1 0 0 l z l z l z l z l z l z l z l z B i + + + + + + + = (6.5-13) The 32-symbol Reed-Solomon Code is generated by thinking of 7 6 5 4 3 2 1 0 , , , , , , , z z z z z z z z as the bits of the symbol. 6.5.1.4 Decoding Similarly, in Section 6.5.1.3, the polynomial ( ) x S is generated as follows from the 5th to 250th symbols of the received message. ( ) 250 249 244 6 245 5 A x A x A x A x S ' + ' + + ' + ' =  (6.5-14) Thus, by employing this R-S encoding/decoding we can detect errors and correct them up until 16 symbol errors occur, by computing 32 polynomials ( ) 143 112 , 11 ～ = j S j o . If no errors exist, ( ) j S 11 o is all zeroes. IS-QZSS Ver. 1.4 189 6.6 Other Information 6.6.1 Instrumental Bias in Receivers It is noted that instrumental bias in receivers should be measured to correct them before shipments. Navigation results using a combination of various frequency signals may have bias without these corrections. IS-QZSS Ver. 1.4 190 7 Provision of QZSS Operational Information and Data via the Internet QZSS operational information and data generated and accumulated data at the MCS will be provided to users via the Internet as specified below. 7.1 QZSS Website for Operational Information and Data Users can access QZSS operational information and data at the following website (“QZ-vision”). This QZSS user website has two language choices, Japanese and English for the international user community. Japanese and English URL: http://qz-vision.jaxa.jp// (Available in the summer of 2010) 7.2 Release of QZSS Information and Data Table 7.2-1 summarizes the QZSS operational information and that will be made publically available, and how users can access this information. Table 7.2-1 Provision of QZSS Information and Data Category Operational Information & Data Users Access 1 Notification Advisory to QZSS Users (NAQU) Announcements regarding interruption or degradation periods, (because of the satellite maintenance schedule Orbit Maintenance or Momentum Management)) constellation status and malfunction reports for QZSS. (Similar to NANU for GPS) On website Distribution by e-mail if requested by users. (Requires E-mail address registration) 2 Experimental Schedule （For Step 1: Demonstration phase） Announcement of test and experiment schedule for users. On website 3 Evaluation Result for System Performances URE information, etc. On website 4 User Operation Support Tool Freeware, supporting several user activities such as QZSS & GPS orbit prediction Download from the website a free User Operation Support Tool that can be run on a user’s PC. Latest almanac, ephemeris data Download from the website（text file） Navigation pattern table On website 5 Precise Orbit & Clock “Ultra Rapid” and “Final” Products for both QZSS and GPS Download from the website（text file） 6 Detailed Information for Precise Satellite Orbit & Clock Estimation Contact Point for researchers will be provided on the website. How to request detailed information, including a contact point, will be described on the website. The requested will be provided by electronic media. 7.2.1 NAQU (NOTICE ADVISORY TO QZSS USERS） NAQU is the QZSS version of NANU（NOTICE ADVISORY TO NAVSTAR USERS provided by the United State Coast Guard Navigation Center for GPS users). The QZSS NAQU service will be provided by JAXA via the QZSS website to inform QZSS users of operational status and planned interruption or degradation of positioning service (because of the satellite maintenance schedule (Orbit Maintenance or Momentum Management)), NAQU will also be used to announce unintentional interruptions or degradation (due to malfunctions or other reasons). The latest NAQU and several previous NAQUs are provided on the website. Moreover, for QZSS users who register their e-mail address, the latest NAQU will be sent by e-mail whenever it is posted to the website. IS-QZSS Ver. 1.4 191 7.2.2 Experimental Schedule As for the technical validation and demonstration of application during phase I, experiments using the LEX signal and L1-SAIF signal will be scheduled and notified to users. Because the LEX signal and L1-SAIF signal messages will at times be defined by research users, it is necessary to announce the experimental schedule for this to users. In addition to the above mentioned NAQU, daily schedule (of 1 week) for planned experiments will be provided on the website indicated in Section 7.1 above. 7.2.3 Evaluation result for System Performances The evaluation result of system performance listed in Table 7.2.3-1 is to be provided as on the website indicated in Section 7.1 above. Table 7.2.3-1 Test Evaluation Public Release Data List No. Data Frequency of Update 1 URE information etc. Monthly 7.2.4 User Operation Support Tool Freeware supporting several user activities such as QZSS & GPS orbit prediction, DOP profile, generation of assist data, schedule planning, etc., will be provided via the website indicated in Section 7.1 above. 7.2.4.1 User Operation Support Tool (QZ-radar) Users can download the free software, User Operation Support Tool (UOST) as well as the associated user’s manual from the website. UOST provides the following functions: (1) Accept input of user’s location and mask information (2) Accept input of epoch, simulation time and orbit parameters such as Ephemeris Data and Almanac Data (3) Calculate GPS and QZSS position, visible satellites, Doppler frequencies, DOP, etc. (4) Output CSV data files (5) Produce plots and graph resulting from the above calculations 7.2.4.2 Provision of Latest Orbital Information Via the website, users can download the latest Almanac Data and Ephemeris Data broadcast by QZSS and GPS. (1) Almanac Data The Almanac Data can be downloaded for all satellites (QZSS and GPS) as well as past archived data. The data format is YUMA*. * YUMA: Refer to the Website of “United State Coast Guard” URL: www.navcen.uscg.gov/?pageName=gpsYuma (14 Jan., 2011) (2) Ephemeris Data The Ephemeris Data can be downloaded for all satellites (QZSS and GPS) as well as past archived data. The data format is the same as ephemeris information of RINEX format. IS-QZSS Ver. 1.4 192 The Ephemeris Data on the website is updated according to the update of broadcast Ephemeris Data from satellites. Ephemeris Data of GPS is the data extracted from GPS navigation message received at the Monitor Station. 7.2.4.3 Provision of navigation pattern table We have made tables of broadcasting order of the data included in each signal (L1C/A, L1C, L2C, L5, LEX) composed of subframes, pages, and messages. We call the tables "Navigation pattern table", and we have made them for every signal. We will provide the "navigation pattern table" for L1C/A signal, L1C signal , L2C signal, L5 signal and LEX signal (for JAXA's experiment only) on the website indicated in Section 7.1 above. 7.2.5 Provision of Precise Orbit & Clock for QZSS and GPS Users can download the following precise orbit and clock data generated at MCS which are useful for scientific use, performance evaluation and Precise Point Positioning (PPP). Clock data are generated based on the QZSST not on GPS time. 7.2.5.1 “Final” Satellite Ephemerides and Clocks The MCS generates the “Final” Satellite Ephemerides and Clocks for all GPS and QZSS satellites for 24 hours with three days latency. The format is the same as the “Final” Satellite Ephemerides and Clocks of the International GNSS Service (IGS) (SP3 format). 7.2.5.2 “Ultra-Rapid” Ephemerides and Clocks The MCS generates broadcast Ephemeris Data from the estimated and propagated satellite position. The estimated and propagated orbit positions without fitting to broadcast ephemeris parameters can be downloaded with the same format as IGS “Ultra Rapid” ephemerides for QZSS (SP3 format). Users can download the set for old GPS as well. GPS “Ultra Rapid” ephemerides provided by the MCS doesn’t include prediction, but only estimated. 7.2.6 Detailed Information for Precise Orbit & Clock Estimation for research purposes Upon request, users of QZSS information for research purposes will be provided operational information and data for precise QZSS orbit & clock estimation by electronic file or media (if it is a large volume). On the website you can see the contact point for the request. Since the information is provided by an off-line process by the operator, it may take about one week for users to obtain. IS-QZSS Ver. 1.4 193 8 Differences with GPS 8.1 Differences in Navigation Messages The QZSS Navigation Messages for each signal (number of bits, scale factor, parameter range, units) are designed to preserve interoperability with GPS to the greatest extent possible. However, based on differences in the conditions unique to GPS and QZSS (QZS satellite orbit conditions, etc.), in some cases QZSS Navigation Messages cannot be expressed using the same definitions as those for GPS. Moreover, in order to provide QZSS with added value not present in GPS, some content has been intentionally defined differently from GPS. For this content, the unique QZSS definitions provided below must be used. Table shows the parameters that have unique QZSS definitions. 8.1.1 Differences with GPS in terms of L1C/A signal Table 8.1.1-1 Parameters with definitions unique to QZSS Subframe Page Parameter GPS definition QZSS definition All All Anti-Spoof flag P code encryption flag Not applicable since there is no P code. AS flag always set to “0”. 1 - C/A or P on L2 L2 code identification (C/A or P) “10” fixed L2P data flag P code message (Y/N) Not applicable since there is no P code T GD LC GPS *2 and L1P (Y) group delay LC QZSS *3 and L1C/A group delay IODC The issue number of the data set, Clock The issue number of the data set, Clock Unlike GPS's IODC, 2bits (MSB) of IODC in QZSS signals are used as counter for SV clock parameter 2 - Ephemeris eccentricity Parameter range is restricted (max. 0.03) Parameter range is not restricted (max. 0.499 ---) Curve Fit Interval 4 hours 2 hours 4 13 NMCT ERD ERD for SV1-31 except for the SV itself transmitting that signal Not only GPS ERD (See Table 5.2.2-3) (User algorithm for NMCT is different from GPS (See section 5.2.2.2.4 (1)) 18 UTC parameter A 0 , A 1 UTC (USNO)－GPST relationship UTC (NICT)－GPST relationship 25 A-S flag, SV conditions P code encryption flag and SV block identification for all GPS Not applicable since there is no P code 4, 5 Subframe 4 2 - 5 7 - 10 Subframe 5 1 – 24 DATA ID Fixed at "01" "00": GPS Almanac "11": QZS Almanac "01","10": Reserved Almanac eccentricity *1 The eccentricity value itself Max. 0.03 Difference with QZS eccentricity 0.06 The difference from Almanac reference Inclination (i 0 ) *1 The inclination value referenced by 0.3 [semi-circles]. Difference with QZS inclination 0.25 [semi-circles]. 25 SV health Health judged by positioning signal output level Health judged by positioning signal C/N at MS - Integrity Status Flag Integrity Assurance Flag QZS-1 does not adopt this flag. Adoption of the flag after “Phase Two” is under study. *1 QZSS definitions apply to QZS parameters only. GPS satellite parameters conform to GPS definitions. *2 LC GPS ： LC GPS is the ionospheric error free linear combination of the L1P(Y) and L2P(Y) signals for GPS. *3 LC QZSS ： LC QZSS is the ionospheric error free linear combination of the L1C/A and L2C signals for QZSS. IS-QZSS Ver. 1.4 194 8.1.2 Differences with GPS in terms of CNAV message on L2C and L5 signals Table 8.1.2-1 Parameters with definitions unique to QZSS Message type Parameter GPS definition QZSS definition *1 10 Ephemeris the offset value of Semi Major Axis 26,559,710 [m] 42,164,200 [m] Ephemeris Eccentricity Parameter range is restricted (max. 0.03) No restrictions on parameter range (max. 0.5) Integrity Status Flag Integrity Assurance Flag QZS-1 does not adopt this flag. Adoption of the flag after “Phase Two” is under study. L2C Phasing Phase relationship between L2C and L2P(Y) QZSS would not adopt this Flag 30 T GD LC GPS *2 and L1P(Y) group delay LC QZSS *3 and L1C/A group delay ISC L1C/A L1P(Y)－L1C/A group delay N/A (Broadcasting value is 0.0) ISC L2C L1P(Y)－L2C group delay L1C/A－L2C group delay ISC L5I5 L1P(Y)－L5I5 group delay L1C/A－L5I5 group delay ISC L5Q5 L1P(Y)－L5Q5 group delay L1C/A－L5Q5 group delay 31, 12 (47, 28) Reduced Almanac Precondition *1 A=26,559,710+δA [m] A=42,164,200+δA[m] (in case of 31 or 12) A=26,559,710+δA [m] (in case of 47 or 28) e＝0 e=0.075 (in case of 31 or 12) e=0 (in case of 47 or 28) i=55 [deg] i=43 [deg] (in case of 31 or 12) i=55[deg] (in case of 47 or 28) Ω ． =-2.6 x 10 -9 [semi-circles/ second] Ω ． =-8.7 x 10 -10 [semi-circles/ second] (in case of 31 or 12) Ω ． =-2.6 x 10 -9 [semi-circles/second] (in case of 47 or 28) ω＝0 [deg] ω＝270 [deg] (in case of 31 or 12) ω＝0 [deg] (in case of 47 or 28) 33 (49) UTC parameter A 0-n 、A 1-n 、A 2-n UTC (USNO)－GPST relationship UTC (NICT)－GPST relationship (in case of 33) UTC (USNO)－GPST relationship (in case of 49) 37(53) Midi Almanac Eccentricity *1 The eccentricity value itself Max. approximately 0.03 Difference with QZS eccentricity 0.06 (in case of 37) The eccentricity value itself (in case of 53) The difference from Midi Almanac Reference Inclination (i 0 ) *1 The inclination value referenced by 0.3 [semi-circles]. Difference with QZS inclination 0.25 [semi-circles] (in case of 37) Difference with GPS inclination 0.3 [semi-circles] (in case of 53) *1 QZSS definitions apply to QZS parameters only. GPS satellite parameters conform to GPS definitions. *2 LC GPS is the ionospheric error free linear combination of the L1P(Y) and L2P(Y) signals for QZSS *3 LC QZSS is the ionospheric error free linear combination of the L1C/A and L2C signals for QZSS IS-QZSS Ver. 1.4 195 8.1.3 Differences with GPS in terms of CNAV2 message on L1C signals Table 8.1.3-1 Parameters with definitions unique to QZSS (1/2) Sub Frame#／Page# Parameter GPS definition QZSS definition* 2/- Ephemeris/ The offset value of Semi Major Axis 26,559,710 [m] 42,164,200 [m] Ephemeris/ Eccentricity Maximum limit is 0.03 Full range without limitation (i.e. Max=0.4999---) ISC L１CP L1P(Y) – L1CP group delay L1C/A – L1CP group delay ISC L１CD L1P(Y) – L1CD group delay L1C/A – L1CP group delay Integrity Status Flag Integrity Status Flag QZS-1 does not adopt this flag . Adoption of the flag after “Phase Two” is under study. 3/1 (or 3/17) UTC parameter/ A 0-n 、A 1-n 、A 2-n UTC(USNO)－GPST relationship UTC(NICT)－GPST relationship (if Page 1) UTC(USNO)－GPST relationship (if Page 17) ISC_L1C/A L1P(Y)－L1C/A group delay The message for QZS-1 is not adopting this parameter on this page/subframe. Future support for this parameter is under study, ISC_L2C L1P(Y)－L2C group delay The message for QZS-1 is not adopting this parameter on this page/subframe. Future support for this parameter is under study, ISC_L5I5 L1P(Y)－L5I5 group delay The message for QZS-1 is not adopting this parameter on this page/subframe. Future support for this parameter is under study, ISC_L5Q5 L1P(Y)－L5Q5 group delay The message for QZS-1 is not adopting this parameter on this page/subframe. Future support for this parameter is under study, IS-QZSS Ver. 1.4 196 Table 8.1.3-1 Parameters with definitions unique to QZSS (2/2) Sub Frame#／Page# Parameter GPS definition QZSS definition* 3/3 （or 3/19） Reduced Almanac/ Equation to get Semi Major Axis (A) from the broadcasted δA in this page* A=26,559,710+δA [m] A=42,164,200+δA[m] (if the PRN number in a packet is 193-197, or page number 3) A=26,559,710+δA [m] (if the PRN number in a packet is not 193-197 and page number is 19) Reduced Almanac/ Assumption of Eccentricity* e＝0  e=0.075 (if the PRN number in a packet is 193-197, or page number 3)  e=0 (if the PRN number in a packet is not 193-197 and page number is 19) Reduced Almanac/ Assumption of Inclination* i=55[deg] i=43[deg] (if the PRN number in a packet is 193-197, or page number3) i=55[deg] (if the PRN number in a packet is not 193-197 and page number is 19) Reduced Almanac/ Assumption of changing rate of right ascension* Ω ． =-2.6 x 10 -9 [semi-circles/second] Ω ． =-8.7 x 10 -9 [semi-circle/ seconds] (if the PRN number in a packet is 193-197, or page number 3) Ω ． =-2.6 x 10 -9 [semi-circles/ second] (if the PRN number in a packet is not 193-197 and page number is 19) Reduced Almanac/ Argument of Perigee* e=0 [deg] e=270 [deg] (if the PRN number in a packet is 193-197, or page number 3) e=0 [deg] (if the PRN number in a packet is not 193-197 and page number is 19) 3/4 (or 3/20) Midi Almanac/ Eccentricity* The eccentricity value itself (Maximum range attainable with indicated bit allocation and scale factor is 0-0.03)  The eccentricity value referenced by 0.06 (if the PRN number in a packet is 193-197, or page number 4)  The eccentricity value itself (if the PRN number in a packet is not 193-197 and page number is 20) Midi Almanac/ The difference from Reference Inclination (i 0 )* The inclination value referenced by 0.3 [semi-circles].  The inclination value referenced by 0.25 [semi-circles] (if the PRN number in a packet is 193-197, or page number 3)  The inclination value referenced by 0.3 [semi-circles] (if the PRN number in a packet is not 193-197 and page number is 20) * QZSS definitions apply to QZS parameters only. GPS satellite parameters conform to GPS definitions. IS-QZSS Ver. 1.4 197 8.2 Difference of RF Characteristics 8.2.1 Difference of Modulated Diffusion Method of Signal The modulated diffusion method of LIC signal for QZS-1 is BOC (1, 1), and not same as MBOC for GPS satellite. We are studying if the modulated diffusion method of LIC signal after “Phase Two” should be MBOC. 8.2.2 Difference of Signal Phase Relation of LIC Signal The carrier phase relation among L1 QZS-1 signals are defined that L1 C/A and L1 CD are same and L1 CP is delayed by 90 degrees as described in Section 5.1.1.1.1. L1 CD and L1 CP for QZS-1 are orthogonal each other at right angles, but L1 CD and L1 CP for GPS are in phase (Figure 5.1.1-1). IS-QZSS Ver.1.4 ANNEX Indoor Messaging System (IMES) IS-QZSS Ver.1.4 A1 A 1 IMES Signal IMES (Indoor Messaging System) 1 signal is designed to realize the indoor positioning, and has a similar property to standard satellite positioning system signal. On the other hand, the positioning method with IMES signal is totally different from standard satellite positioning method. This method is very simple and practical for specifying the position simply by demodulating and decoding the modulated navigation message. This method requires only a small customization of existing GPS receivers. In this sense, IMES has similar advantage as QZSS signal and research has been made for the promotion of QZSS. QZSS is designed to improve the availability of positioning feasible area and time in both urban and mountainous area, and IMES is designed to realize the indoor positioning which is difficult by satellite-based positioning. Both systems are intended to improve the efficiency and availability of positioning environment, that is to realize the seamless positioning in both indoor and outdoor environment. This appendix describes the signal specification of IMES-L1C/A signal which has same RF characteristics as L1C/A signal and IMES-L1C signal which has same RF characteristics as L1C signal of GPS and QZSS. Installation of IMES signals transmitter and its operation concept is also explained. IMES signal is designed by JAXA to contribute the development of QZSS-ready receivers as well as satellite positioning applications by realizing the seamless positioning environment. However, IMES signal transmitter is not part of the QZSS component, further development and installation by a third party is expected based on this specification. Please note that the PRN code set for "IMES" is ONLY authorized by US GPSW to use in JAPAN, currently. The specification of "IMES Signal" defined in this appendix is only valid in Japan. * We will set up "IMES consortium" and study finalization of the specification of IMES signal & message, and development of the guideline for installation and operation of IMES equipments in the consortium. The conclusion will be reflected in this document. The issue of time crunch for reading IMES message (discussed in QZSS user meeting (for IMES) on 22 DEC. 2010) will be studied in IMES consortium and be finalized the specification during FY2011. A 1.1 IMES signal specification A 1.1.1 IMES signal -L1C/A type-signal specification IMES signal -L1C/A type-(IMES-L1C/A) has the same RF characteristic as L1C/A of GPS and QZSS Navigation message structure is same in terms of 30 bits word unit, but has frame structure in terms of one word at the shortest to achieve fast TTRM (Time to Read Message). The following describes the specifications by distinguishing RF characteristics and message characteristics. A 1.1.1.1 RF characteristics A 1.1.1.1.1 Signal structure A 1.1.1.1.1.1 Nominal center carrier frequency Nominal center carrier frequency is 1575.4282 MHz or 1575.4118 MHz, and deviation is ±0.2ppm 1 Patent pending by JAXA, GNSS Technology Inc. and Lighthouse Technology and Consulting Co. (2 patents for "Positional information providing system, Positional information providing apparatus and transmitter" (Japanese Patent No. 4296302 and 4461235) have been approved.) IS-QZSS Ver.1.4 A2 A 1.1.1.1.1.2 PRN spreading frequency PRN spreading frequency is one hundred fifty fourth part of nominal center carrier frequency. The carrier and PRN code should keep coherence. A 1.1.1.1.1.3 PRN spreading modulation method The carrier should be BPSK (1) modulated on C IMES-L1C/A bit strings by PRN code and navigation message. A 1.1.1.1.1.4 Frequency bandwidth 2.046MHz or more including main-lobe. A 1.1.1.1.2 Signal power level A 1.1.1.1.2.1 Minimum signal power level at the receiver input The minimum received power measured by the receiving antenna having gain of 0dBi for right-handed circularly polarized wave should be installed and configured in -158.5 dBW or more at the input terminal of receiver having antenna gain of 0dBi for right-handed circularly polarization. A 1.1.1.1.2.2 Maximum signal power level at the receiver input In cases where the power of the receiving GPS signal is estimated in -158.5dBW or more measured by the receiving antenna having gain of 0dBi for right-handed circularly polarization, the maximum received power of IMES signal should be installed and configured in -140 dBW or less at the input terminal of receiver having antenna gain of 0dBi for right-handed circularly polarization. In cases where the power of the receiving GPS signal is estimated in less than -158.5dBW measured by the receiving antenna having gain of 0dBi for right-handed circularly polarization, the maximum received power of IMES signal should be installed and configured in -150 dBW or less at the input terminal of receiver having antenna gain of 0dBi for right-handed circularly polarization. A 1.1.1.1.2.3 Maximum signal power level at the transmitter output Equivalent Isotropically Radiated Power (EIRP) should be installed and configured in -94.35 dBW or less at the output of IMES signal transmitter. A 1.1.1.1.3 PRN code Same code sequence as PRN code of C/A signal of applicable document (1), see the applicable document (1) from number 173 to 182. NOTE: Those set of PRN code are NOT allowed to use outside of Japan currently. A 1.1.1.1.4 Navigation message Same word structure, bit rate, and modulation scheme of applicable document (1). A 1.1.1.1.5 Carrier wave characteristics A 1.1.1.1.5.1 Correlation loss Correlation loss means the difference between the transmitted power and received power by reverse diffusion. Correlation loss power level is 1.2dB or less. IS-QZSS Ver.1.4 A3 A 1.1.1.1.5.2 Carrier phase noise Carrier phase noise of unmodulated carrier wave before PRN code and navigation message are superposed should keep the level which PLL of 10Hz one sideband of PLL is able to phase tracking at 0.2rad (RMS). A 1.1.1.1.5.3 Spurious characteristics Spurious power level is -40 dB or less to unmodulated carrier power level within frequency band. A 1.1.1.1.5.4 Polarization characteristics This means the right-hand circularly polarized spread spectrum signal or the linearly polarized spread spectrum signal. And axis ratio guarantees minimum signal power level. A 1.1.1.2 Message Characteristics A 1.1.1.2.1 Word structure One word is made up of 30 bits, which is 21bits of data bits and 3 bits of word counter, 6 bits of parity. A 1.1.1.2.1.1 Word counter The 3 bits after second word in the frame which has multiple words is “Word counter”. This “word counter” increment every word transmission including word that word counter is not included. Identifying the segment of word and frame is assisted with word counter. This 3 bits value skips instead of taking the same value as first 3 bits of preamble for the assist of identifying the segment. A 1.1.1.2.1.2 Parity The 6 bit parity code added to the end of 30 bit word is the same (32.26) Hamming code as specified in 20.3.5.1 of applicable documents (1). This parity assists identifying word segment. (1) Parity Algorithm The 6 bit parity code added to the end of 30 bit word is the same (32.26) Hamming code as specified in 20.3.5.1 of applicable documents (1). (2) Parity Check Algorithm Same as the applicable document (1) in section 20.3.5.2. A 1.1.1.2.2 Frame structure One frame is made (consists) of multiple number of integer of one word and has following style indicated on the figures shown in Figure 1.1.1-1. This figure indicates the example by 3 words/frame. In case of over 4 words/frame, 3 bits word counter is repeated after second word as necessary times. That is to say, first word comes with 8 bit preamble and 3 bits message type ID (MID) follows. The others bits are all data bit except above 3 bits word counter and 6 bits parity. IS-QZSS Ver.1.4 A4 Bits -> 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 COUNT Data Bits COUNT Data Bits COUNT Data Bits Parity Parity Parity Data Bits Data Bits in case of 3 words/frame in case of 2 words/frame Parity Preamble Parity Messag e Type ID Messag e Type ID Data Bits in case of 1 word/frame Preamble Preamble Parity Messag e Type ID Figure 1.1.1-1 IMES L1C/A frame structure IS-QZSS Ver.1.4 A5 A 1.1.1.2.2.1 Preamble The 8 bits preamble added to the beginning of the first word of each frame is 8B (H) Identifying the each word and frame segment is assisted with this preamble. This value allows the identification of IMES signal from GPS and QZSS, unlike the applicable document (1) in section 20.3.3.1. A 1.1.1.2.2.2 Message type ID (MID) 3 bits message type ID (MID) which is added to the preamble of the first word of each frame indicates its frame length and contents. Table 1.1.1-1 shows the MID value and its associated frame length, contents, and Maximum Repetition Cycle (s). The Maximum repetition Cycle is defined that absolute position information is sent from the IMES transmitter at each cycle. Because of this, users could get not only ID type message but also absolute position information without data server for disaster-management in emergency situations. Table 1.1.1-1 Definition of IMES L1C/A message type ID MID Frame Length (words) Contents Maximum Repetition Cycle (s) (provisional) 0 3 Position 1 12 1 4 Position 2 2 - reserved - 3 1 Short ID - 4 2 Medium ID - 5 - Reserved - 6 - Reserved - 7 - Reserved - A 1.1.1.2.3 Message contents A 1.1.1.2.3.1 Message type ID ”000” position data 1 When the Message type ID is ”000”, the frame length is 3 words and its contents indicates the position data. This position data will be consistent with the position data code using Ucode defined and managed by Geographical Survey Institute. Frame structure is indicated on the Figure 1.1.1-2, refers to the Table 1.1.1-2 for the LSB and numerical range. (1) Floor number The first word bit 12 to 19 indicated the floor number where the transmitter is placed, and FL(th) is the unit. Bits are unsigned 8 bit and LSB is a floor. As it is indicated in the equation below, -50FL to +204FL is the range of these bits by setting the offset at -50 FL. ] [ 50 2 FL r FloorNumbe rBits FloorNumbe   (2) Latitude The second word bit 4 as signed bit, bit 5 to 24 as MSB, and the bits 20 and 21 in the first word as LSB, are the latitude of transmitter and degree is the unit. IS-QZSS Ver.1.4 A6 These total 23 bits are singed, LSB is [deg] 000021 . 0 [deg] 2 / 90 22  , and the range is from 0deg to +90deg (from -90deg to +90deg with signed bit). It is equivalent to nearly 2.4m in the north and south direction. (3) Longitude The third word bit 4 as signed bit, bit 5 to 24 as MSB, and the bits 22-24 in the first word as LSB, are the longitude of transmitter and degree is the unit. These total 24 bits are signed, LSB is [deg] 000021 . 0 [deg] 2 / 180 23  , and the range is from 0deg to +180deg (from -180deg to +180deg with signed bit). It is equivalent to nearly 2.4m in the east and west direction on the equator. Bits -> 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 word 1 0 0 0 word 2 word 3 L o n L S B 3 b i t s Parity 6bits Preamble, 8bit MSG Type, 3bit L a t L S B Floor 8bit Parity 6bits Parity CNT 3bit CNT 3bit Latitude 21bits (MSB) Longitude 21bits (MSB) Figure 1.1.1-2 IMES-L1C/A MID=000 « Position 1 » Frame Structure Table 1.1.1-2 IMES-L1C/A MID=000 « Position 1 » Contents ~ 1 ~ 2 ~ 3 ~ 24 8 Bit Length Content 23 # Floor Latitude Longitude (2.39 m) (2.39 m) 1 ｔｈ LSB 2.1E-05 deg 2.1E-05 deg -50 ｔｈ -180 deg -90 deg Range maximum minimum 204 ｔｈ 90 deg 180 deg A 1.1.1.2.3.2 Message type ID ”001” position data 2 When the Message type ID is ”001”, this frame length is 4 words and its content indicates the position data. Frame structure is indicated on the Figure 1.1.1-3, and refers to the Table 1.1.1-3 for the LSB and range. (1) Floor number The first word bit 12 to 20 indicated the floor number where the transmitter is placed, and FL(th) is the unit. Bits are unsigned 9 bits and LSB is 0.5 floor. As it is indicated in the equation below, -50FL to +205FL is the range of these bits by setting the offset at -50 FL. ] [ 50 2 5 . 0 FL r FloorNumbe rBits FloorNumbe    IS-QZSS Ver.1.4 A7 (2) Latitude The second word bit 4 as signed bit, bit 5 to 24 as MSB, and the bits 18-20 in the fourth word as LSB, are the latitude of transmitter and degree is the unit. These total 24 bits are signed, LSB is [deg] 000011 . 0 [deg] 2 / 90 23  , and the range is from 0deg to +90deg (from -90deg to +90deg with signed bit). It is equivalent to nearly 1.2m in the north and south direction. (3) Longitude The third word bit 4 as signed bit, bit 5 to 24 as MSB, and the bits 21-24 in the fourth word as LSB, are the longitude of transmitter and degree is the unit. These total 25 bits are signed, LSB is [deg] 000011 . 0 [deg] 2 / 180 24  , and the range is from 0deg to +180deg (from -180deg to +180deg with signed bit). It is equivalent to nearly 2.4m in the east and west direction on the equator. (4) Altitude Fourth word bit 4 to 15 are the altitude of transmitter, and m (meter) is the unit. These total 12 bits are unsigned, and as it is indicated in the equation below, it indicates the value in the range from -95m to +4000m by setting the offset at -95m. ] [ 95 2 m Altitude ts AltitudeBi   Bits -> 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 word 1 0 0 1 word 2 word 3 word 4 CNT 3bit Altitude 12 bits L a t ( L S B ) rese rved r e s e r v e d L o n ( L S B ) Floor 9 bits Parity 6bits Parity CNT 3bit Latitude 21bits (MSB) CNT 3bit Longitude 21bits (MSB) Parity 6bits Preamble, 8bit MSG Type, 3bit Parity Figure 1.1.1-3 IMES-L1C/A MID=001 « Position 2 » Frame Structure Table 1.1.1-3 IMES-L1C/A MID=001 « Position 2 » Contents ~ 1 ~ 2 ~ 3 ~ 4 ~ 4000 m 90 deg 180 deg 205 ｔｈ Range # maximum 25 12 Bit Length Content 24 Altitude Latitude Longitude (1.19 m) (1.19 m) 1 m LSB 1.1E-05 deg 1.1E-05 deg -95 m -180 deg -90 deg minimum Floor 9 0.5 ｔｈ -50 ｔｈ IS-QZSS Ver.1.4 A8 A 1.1.1.2.3.3 Message type ID ”011” short ID In the event that Message type ID is ”011”, this frame length is 1 word and its contents is short ID(ID S ). Figure 1.1.1-4 shows the frame structure and ID S of 12 bit is transmitted. ID S= 111111100000～111111111111 is the bit pattern reserved for some specific purposes, for instance, emergency message when disaster occurs, should not be used in general. Bits -> 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 word 1 0 1 1 Parity 6bits Preamble, 8bit MSG Type, 3bit Short ID (ID S ) 12 bits B D 1 b i t Figure 1.1.1-4 IMES-L1C/A MID=011 « Short ID » Frame Structure A 1.1.1.2.3.4 Message type ID ”100” Medium ID In the event that Message type ID is ”100”, this frame length is 2 words and its contents is medium ID(ID M ). Figure 1.1.1-5 shows the frame structure and ID M (length=33 bits) is transmitted. Bits -> 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 word 1 1 0 0 word 2 CNT 3bits Medium ID (ID M ) LSB 21 bits Parity 6bits Parity 6bits Preamble, 8bit MSG Type, 3bit Medium ID (ID M ) MSB 12 bits B D 1 b i t Figure 1.1.1-5 IMES-L1C/A MID=100 « Medium ID » Frame Structure A 1.1.2 IMES-L1C type-signal specification TBD IS-QZSS Ver.1.4 A9 A 1.2 Installation of transmitter This chapter is scheduled to explain the transmitter installation such as the example of separation distance between transmitter and receiver as below, as well as the interval between transmitters, and how to choose the PRN number for each transmitter, etc. A 1.2.1 Examples of separation distance from transmitter to receiver Examples of separation distance and transmitter EIRP in accordance with maximum receiving power limit of IMES signal L1C/A type is shown in Figure 1.2.1-1. Figure 1.2.1-1 Examples of separation distance and transmitter EIRP in accordance with maximum receiving power limit of IMES signal A 1.3 Operation concept This chapter is schedule to describe the application examples of IMES for indoor positioning.
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