Aircraft Communication and Navigation

Aircraft Communications and Navigation Systems: Principles, Operation and Maintenance Weather radar and ILS antennas in the nose radome of a Boeing 757 aircraft . Aircraft Communications and Navigation Systems: Principles. Operation and Maintenance Mike Tooley and David Wyatt AMSTERDAM • BOSTON • HEIDELBERG • LONDON • NEW YORK • OXFORD PARIS • SAN • DIEGO • SAN FRANCISCO • SINGAPORE • SYDNEY • TOKYO Butterworth-Heinemann is an imprint of Elsevier . com/locate/permissions. Designs and Patents Act 1988 No part of this publication may be reproduced. email: [email protected]. in particular. mechanical. MA 01803. Jordan Hill. photocopying. Burlington. UK: phone (+44) (0) 1865 843830. Suite 400. 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Oxford OX2 8DP. or from any use or operation of any methods. negligence or otherwise. 2 3.9 2.12 2.9 3.6 2.12 3.3 3.4 1.2 1.3 1.13 Chapter 3 3.1 1.7 3.4 3.10 2.5 2.6 3.11 3.7 2.11 2.1 2.1 3.Contents Preface Acknowledgements Online resources Chapter 1 1.9 Chapter 2 2.3 2.13 Introduction The radio frequency spectrum Electromagnetic waves Frequency and wavelength The atmosphere Radio wave propagation The ionosphere MUF and LUF Silent zone and skip distance Multiple choice questions Antennas The isotropic radiator The half-wave dipole Impedance and radiation resistance Radiated power and efficiency Antenna gain The Yagi beam antenna Directional characteristics Other practical antennas Feeders Connectors Standing wave ratio Waveguide Multiple choice questions Transmitters and receivers A simple radio system Modulation and demodulation AM transmitters FM transmitters Tuned radio frequency receivers Superhet receivers Selectivity Image channel rejection Automatic gain control Double superhet receivers Digital frequency synthesis A design example Multiple choice questions xi xiv xiv 1 1 3 4 4 5 7 10 12 13 15 15 16 18 19 19 20 22 24 28 32 33 38 39 41 41 42 43 44 45 46 47 50 51 51 53 55 59 .7 1.10 3.5 1.5 3.8 2.8 1.8 3.6 1.4 2.2 2. 3 Chapter 7 7.6 5.10 Chapter 5 5.7 Chapter 6 6.4 8.3 9.1 6.3 5.5 7.9 4.6 8.8 4.2 9.8 Chapter 9 9.1 9.5 VHF communications VHF range and propagation DSB modulation Channel spacing Depth of modulation Compression Squelch Data modes ACARS VHF radio equipment Multiple choice questions HF communications HF range and propagation SSB modulation SELCAL HF data link HF radio equipment HF antennas and coupling units Multiple choice questions Flight-deck audio systems Flight interphone system Cockpit voice recorder Multiple choice questions Emergency locator transmitters Types of ELT Maintenance and testing of ELT ELT mounting requirements Typical ELT Cospas–Sarsat satellites Multiple choice questions Aircraft navigation The earth and navigation Dead reckoning Position fixing Maps and charts Navigation terminology Navigation systems development Navigation systems summary Multiple choice questions Automatic direction finder Introducing ADF ADF principles ADF equipment Operational aspects of ADF Multiple choice questions Contents 61 61 62 63 63 64 65 65 68 70 72 73 73 74 76 76 80 81 84 85 85 90 92 93 93 94 95 97 98 100 101 101 104 105 106 107 107 114 116 117 117 117 118 122 125 .7 8.2 8.1 4.3 4.4 9.6 Chapter 8 8.3 8.1 7.2 7.2 6.7 4.5 8.3 7.5 4.2 4.6 4.5 5.4 7.vi Chapter 4 4.4 4.1 8.2 5.4 5.1 5. 4 15.Contents Chapter 10 10.5 11.1 15.6 12.4 11.2 15.7 Chapter 15 15.6 15.3 10.2 12.1 11.7 12.7 VHF omnidirectional range VOR principles Airborne equipment Operational aspects of VOR Multiple choice questions Distance measuring equipment Radar principles DME overview DME operation Equipment overview En route navigation using radio navigation aids Multiple choice questions Instrument landing system ILS overview ILS ground equipment ILS airborne equipment Low range radio altimeter ILS approach Autoland Operational aspects of the ILS Multiple choice questions Microwave landing system MLS overview MLS principles Aircraft equipment Ground equipment MLS summary Multiple choice questions Hyperbolic radio navigation Hyperbolic position fixing Loran overview Loran-C operation Loran-C ground equipment Loran-C airborne equipment Enhanced Loran (eLoran) Multiple choice questions Doppler navigation The Doppler effect Doppler navigation principles Airborne equipment overview Typical Doppler installations Doppler summary Other Doppler applications Multiple choice questions vii 127 127 131 136 139 141 141 142 143 143 145 149 151 151 151 155 159 160 160 161 162 163 163 163 166 168 168 168 171 171 173 173 175 176 177 178 179 179 179 183 184 184 185 186 .3 13.1 14.6 14.5 15.3 11.5 14.5 13.2 11.1 13.6 Chapter 14 14.5 12.4 Chapter 11 11.1 10.3 14.3 15.2 10.4 12.8 Chapter 13 13.4 14.4 13.1 12.2 14.6 Chapter 12 12.3 12.2 13. 1 17. navigation and surveillance/air traffic management Multiple choice questions Contents 187 187 191 196 198 199 201 201 204 204 211 214 214 214 215 217 217 217 217 218 221 221 223 224 225 227 227 227 230 232 236 237 239 239 240 243 251 251 252 253 253 254 255 256 265 267 270 .4 21.2 17.5 18.1 18.5 20.3 17.3 16.7 17.2 20.2 16.2 21.6 18.1 21.1 20.2 18.3 20.2 19.7 Area navigation RNAV overview RNAV equipment Kalman filters Required navigation performance Multiple choice questions Inertial navigation systems Inertial navigation principles System overview System description Alignment process Inertial navigation accuracy Inertial navigation summary System integration Multiple choice questions Global navigation satellite system GPS overview Principles of wave propagation Satellite navigation principles GPS segments GPS signals GPS operation Other GNSS The future of GNSS Multiple choice questions Flight management systems FMS overview Flight management computer system System initialisation FMCS operation FMS summary Multiple choice questions Weather radar System overview Airborne equipment Precipitation and turbulence System enhancements Lightning detection Multiple choice questions Air traffic control system ATC overview ATC transponder modes Airborne equipment System operation Automatic dependent surveillance-broadcast Communications.3 19.viii Chapter 16 16.4 17.6 Chapter 21 21.6 17.4 18.5 Chapter 17 17.6 Chapter 20 20.7 18.8 Chapter 18 18.3 21.9 Chapter 19 19.5 19.5 21.4 16.1 19.6 21.3 18.1 16.4 20.4 19.8 18.5 17. 4 22.3 22.1 22.5 Appendices 1 2 3 4 Index Traffic alert and collision avoidance system Airborne collision avoidance systems TCAS overview TCAS equipment System operation Multiple choice questions Abbreviations and acronyms Revision papers Answers Decibels ix 271 271 272 275 277 283 285 285 291 297 303 305 .2 22.Contents Chapter 22 22. . It is important to realise that this book is not designed to replace aircraft maintenance manuals. horn and parabolic dish radiators. corner reflectors. radiated power. The aim has been to make the subject material accessible and presented in a form that can be readily assimilated. Nor does it attempt to provide the level of detail required by those engaged in the maintenance of specific aircraft types. image channel rejection and automatic gain control (AGC) are important requirements of a modern radio receiver and these topics are introduced before moving on to describe more complex receiving equipment. global data communication has recently . The book provides syllabus coverage of the communications and navigation section of Module 13 (ATA 23/34). The book provides an introduction to the principles. This chapter explains the principles of isotropic and directional radiating elements and introduces a number of important concepts including radiation resistance. Selectivity. this book should appeal to members of the armed forces and others attending training and educational establishments engaged in aircraft maintenance and related aeronautical engineering programmes (including BTEC National and Higher National units as well as City and Guilds and NVQ courses). The chapter also describes the various mechanisms by which radio waves propagate together with a detailed description of the behaviour of the ionosphere and its effect on radio signals. Yagi beam antennas. Several practical forms of antenna are described including dipoles. gain and efficiency. The chapter concludes with a brief introduction to waveguide systems. In addition. The book assumes a basic understanding of aircraft flight controls as well as an appreciation of electricity and electronics (broadly equivalent to Modules 3 and 4 of the EASA Part-66 syllabus). Modern aircraft radio equipment is increasingly based on the use of digital frequency synthesis and the basic principles of phase-locked loops and digital synthesisers are described and explained. The chapter also provides an introduction to the aircraft communication addressing and reporting system (ACARS). Instead it has been designed to convey the essential underpinning knowledge required by all aircraft maintenance engineers. This chapter provides readers with an introduction to the operating principles of AM and FM transmitters as well as tuned radio frequency (TRF) and supersonic-heterodyne (superhet) receivers. connectors and standing wave ratio (SWR). They are particularly useful to the ‘self-starter’ and to those wishing to update or upgrade their aircraft maintenance licence. Antennas are introduced in Chapter 2. High frequency (HF) radio provides aircraft with an effective means of communicating over long distance oceanic and trans-polar routes. technicians and engineers engaged in engineering maintenance activities on commercial aircraft. Chapter 4 describes the principles of VHF communications (both voice and data). In addition. quarter wave (Marconi) antennas. This book is designed to cover the essential knowledge base required by certifying mechanics. antenna impedance. Chapter 1 sets the scene by providing an explanation of electromagnetic wave propagation and the radio frequency spectrum. Radio transmitters and receivers are the subject of Chapter 3.Preface The books in this series have been designed for both independent and tutor assisted studies. Very high frequency (VHF) radio has long been the primary means of communication between aircraft and the ground. Chapter 2 also provides an introduction to feeders (including coaxial cable and open-wire types). operation and maintenance of aircraft communications and navigation systems. The series also provides a useful source of reference for those taking ab initio training programmes in EASA Part 147 and FAR 147 approved organisations as well as those following related programmes in further and higher education institutions. this sets the scene for the remaining chapters of the book. dead reckoning etc. and is described in Chapter 10. The system provides multiple approach angles for both azimuth and elevation guidance. This system is in widespread use throughout the world today. a decision was made to develop a radio navigation system based on VHF. Chapter 11 develops this theme with a system for measuring distance to a navigation aid. Chapter 13 continues with the theme of guided approaches to an airfield. There are a number of shortcomings with ILS. it was evident to the aviation world that an accurate and reliable shortrange navigation system was needed. ADF is a short–medium range (200 nm) navigation system providing directional information. Preface During the late 1940s. this links very well into the previous chapters of the book describing fundamental principles of radio transmitters. and concludes with some practical aspects associated with the operational use of ADF. Chapter 8 introduces the subject of aircraft navigation. This is a short/medium-range navigation system. elevation and range. azimuth. Chapter 6 describes flight-deck audio systems including the interphone system and allimportant cockpit voice recorder (CVR) which captures audio signals so that they can be later analysed in the event of a serious malfunction of the aircraft or of any of its systems. and introduces some basic aircraft navigation terminology. Long-range radio navigation systems are described in Chapter 14. e. longitude. These navigation aids cannot however be used for precision approaches and landings. The chapter also provides a brief introduction to satellite-based location techniques. ADF. Navigation is the science of conducting journeys over land and/or sea. The chapter concludes by reviewing a range of navigation systems used on modern transport and military aircraft. The advent of radar in the 1940s led to the development of a number of navigation aids including distance measuring equipment (DME). receivers and antennas. MLS provides threedimensional approach guidance. Chapter 12 describes how the ILS can be used for approach through to autoland.g.xii been made possible using strategically located HF data link (HFDL) ground stations. i. Radio waves have directional characteristics as described in the early chapters of the book. The system is based on the principle of time referenced scanning beams and provides precision navigation guidance for approach and landing. The detection and location of the site of an air crash is vitally important to the search and rescue (SAR) teams and also to potential survivors. Since radio communication systems based on very high frequency (VHF) were being successfully deployed.e. Despite the advantages of MLS. VOR and DME navigation aids are installed at airfields to assist with approaches to those airfields. As well as communication with ground stations. one of earliest forms of radio navigation that is still in use today. This system became the VHF omnidirectional range (VOR) system. Military operators of MLS often use mobile equipment that can be deployed within hours. in 1978 the microwave landing system (MLS) was adopted as the longterm replacement. The standard approach and landing system installed at airfields around the world is the instrument landing system (ILS). it has not yet been introduced on a worldwide basis for commercial aircraft. VOR is the basis of the current network of ‘airways’ that are used in navigation charts. Chapter 7 describes the construction and operation of emergency locator transmitters (ELT) fitted to modern passenger aircraft. This chapter reviews some basic features of the earth’s geometry as it relates to navigation. reviews some typical ADF hardware that is fitted to modern commercial transport aircraft. latitude. often used in conjunction with the VOR system to provide accurate navigation fixes. These systems are based . Chapter 9 looks at the historical background to radio navigation. The system is based on secondary radar principles. Many aircraft navigation systems utilise radio frequency methods to determine a position fix. modern passenger aircraft require facilities for local communication within the aircraft. Chapter 5 describes the principles of HF radio communication as well as the equipment and technology used. The ILS uses a combination of VHF and UHF radio waves and has been in operation since 1946. This is the basis of the automatic direction finder (ADF). An emerging ATC technology is ADS-B. This system requires no external inputs or references from ground stations. wind direction etc. Ground controllers use the system to address individual aircraft. this is the subject of Chapter 17. or planned for future deployment. The term ‘navigation’ can be applied in both the lateral and vertical senses for aircraft applications. Vertical navigation is concerned with optimising the performance of the aircraft to reduce operating costs. Increasing traffic density. coastlines and mountains. The need for improved traffic flow led to the introduction of the traffic alert and collision avoidance system (TCAS). and the subsequent demands on air traffic control (ATC) resources. Chapter 15 looks at a unique form of dead reckoning navigation system based on radar and a scientific principle called Doppler shift. The system was developed in the 1950s for use by the US military and subsequently the space programmes. i.g.e. the system can be used for long distance navigation and by helicopters during hover manoeuvres. or filtering. The system does not need radio navigation inputs and it does not transmit radio frequencies. During the 1980s. A secondary use of weather radar is the terrain-mapping mode that allows the pilot to identify features of the ground. wind speed. xiii Navigation by reference to the stars and planets has been employed since ancient times. this is also covered in Chapter 21. With ever increasing air traffic congestion. Area navigation is a means of combining. The advent of computers. Inertial navigation systems (INS) were introduced into commercial aircraft service during the early 1970s. An artificial constellation of navigation aids was initiated in 1973 and referred to as Navstar (navigation system with timing and ranging). Being self-contained. this is described in Chapter 16. Radar was introduced onto passenger aircraft during the 1950s to allow pilots to identify weather conditions and subsequently reroute around these conditions for the safety and comfort of passengers. in particular the increasing capabilities of integrated circuits using digital techniques. lateral navigation and performance management functions were combined into a single system known as the flight management system (FMS). Chapter 20 reviews how the planned journey from A to B could be affected by adverse weather conditions. e. it is now widely available for use in many applications including aircraft navigation. distance to waypoint. Omega and Loran. they are also being proposed as a complementary navigation aid for global navigation satellite systems. Loran systems are still available for use today as stand-alone systems. they were introduced in the 1940s to provide en route operations over oceans and unpopulated areas. the system can be used for long distance navigation over oceans and undeveloped areas of the globe. Being self-contained. the risk of a mid-air collision increases. aircraft navigators have utilised periscopes to take celestial fixes for long distance navigation. inputs from one or more navigation sensors and defining positions that are not necessarily co-located with groundbased navigation aids. One example of this is the area navigation system (RNAV). has led to a number of advances in aircraft navigation. Various tasks previously routinely performed by the crew can now be automated with the intention of reducing crew workload. including Decca. Several hyperbolic systems have been developed since. The inertial navigation system is an autonomous dead reckoning system. rivers.Preface on hyperbolic navigation. ground speed. it requires no external inputs or references from ground stations. in particular around airports. this is the subject of Chapter 19. This global positioning system (GPS) was developed for use by the US military. Chapter 18 looks at GPS and other global navigation satellite systems that are in use. The system is able to compute navigation data such as present position. The operational use of Omega and Decca navigation systems ceased in 1997 and 2000 respectively. heading. A major advance in aircraft navigation came with the introduction of the inertial navigation system (INS). The ATC system is based on secondary surveillance radar (SSR). means that we need a method of air traffic control (ATC) to manage the flow of traffic and maintain safe separation of aircraft. this is the subject of . Doppler navigation systems were developed in the mid-1940s and introduced in the mid-1950s as a primary navigation system. The system is functionally independent of ground stations. Trevor Diamond for the ADF. Preface Online resources Additional supporting material (including video clips. Kearfott (Guidance & Navigation Corporation) and Northrop Grumman Corporation for permission to reproduce data on their inertial navigation systems and sensors. thanks also go to Alex Hollingsworth.66web. Further examination practice can be gained from the four revision papers given in Appendix 2. the International Loran Association (ILA) and US Coast Guard for information and data on both the existing LoranC infrastructure and their insight into future developments.co. Finally.xiv Chapter 22. The review questions at the end of each chapter are typical of these used in CAA and other examinations.key2study. CMC Electronics for data and photographs of Doppler and MLS hardware. Lucy Potter and Jonathan Simpson at Elsevier for their patience.uk or www. encouragement and support.com/66web Acknowledgements The authors would like to thank the following persons and organisations for permission to reproduce photographs and data in this book: Lees Avionics and Wycombe Air Centre for product/cockpit images. ADSB Technologies. sound bites and image galleries) for this book are available at www. ARINC for information relating to TCAS. The book concludes with four useful appendices. TCAS is an airborne system based on secondary radar that interrogates and replies directly with aircraft via a highintegrity data link. . Other features that will be particularly useful if you are an independent learner are the ‘key points’ and ‘test your understanding’ questions interspersed throughout the text. including a comprehensive list of abbreviations and acronyms used with aircraft communications and navigation systems. TCAS is an automatic surveillance system that helps aircrews and ATC to maintain safe separation of aircraft. VOR and DME photographs. and alerts the crew if another aircraft comes within a predetermined time to a potential collision. LLC for their permission to reproduce data on automatic dependent surveillance-broadcast.