AEROSPACE TELEMETRYCH.UMAKALYANI Department of Electrical and Communication Engineering Ramachandra College of Engineering, Eluru. Abstract: Aerospace telemetry is the “science of transmission of information from air space vehicles to an accessible location”. Aerospace telemetry and the reception of flight test data are key components to flight test in ascertaining positional data for further analysis. Data gathered by a telemetry system is critical to the success of every aeronautical research project and reliable equipment is needed to keep the telemetry system, from the aircraft to the ground, transmitting and receiving every moment data is needed. This research paper introduces and defines telemetry and aerospace telemetry, provides a brief history of how telemetry came about, briefly captures some telemetry applications, introduces the telemetry equipment requirements necessary for telemetry to occur, such as signal conditioning and subcarrier oscillator equipment, outlines some telemetry concerns, such as noise and errors, and presents ways to minimize these errors using transducer, data system, and physical end-to-end calibrations. 1. INTRODUCTION This paper will provide an understanding of the many aspects of aerospace telemetry. The next few sections define telemetry and aerospace telemetry, provide a brief history of telemetry, and further emphasize key telemetry aspects using a few telemetry application examples. 1.1 Aerospace Telemetry: Telemetry is a “technology that allows the remote measurement and reporting of information of interest to the system designer or operator”. Information, in this case, is data that is organized as a result of processing or manipulation, which adds to the knowledge of the receiver. The Greek root tele means remote and metron means to measure. Other sources define telemetry as “the science of the use of the telemeter” 14, and further define telemeter as “an instrument for determining distance of an object, such as the distance target in gunnery”. One early example of this science existed in Italy in t he early 17th century. An Italian astronomer named Porro used a quick measurement technique called tachymetry to determine distances. Porro used an optical method with fixed stadia hairs in a focal plane and a variable length graduated horizontal base at a remote location where the distance was observed. Telemetry can also be considered as the science of transmission of inaccessible data to accessible locations. Aerospace telemetry further defines telemetry as the science of “transmission of information from air and space vehicles to accessible locations”. This definition extended the conventional notion for telemetry. For example, although receiving stations are generally located on Earth, they may also be located within air and space vehicles remote from the vehicles containing the transmitting stations. Telemetry equipment was used on a limited basis by aircraft manufacturers before World War II (WWII). During WWI. Timing of the pulse-type wired TM systems were often mechanically generated using a ratchet like device. “Data stations” transmit back real time to a base station and identify the major parameters needed to make good “cropgrowing” decisions. the TM data was transmitted using the electric power lines themselves. However. medicine. as compared to voltage or current-type systems. This TM system transmitted the data using the city’s existing telephone line network10. Pulse-type wired telemetry was also developed during the 1920s. At the receiving end.S. solar radiation. wildlife study and management.S. a U. and water management. one of the twentieth century’s first TM systems was installed in Chicago. 2. The timely availability of weather and soil data plays a crucial role in most activities related to healthy crop stations plays a major role in disease prevention and precision irrigation. 2. In 1912. and transmitted data on its several electric power generating plants to a central control station. This voltage was connected to a line.1.S. If there was no leakage in the line. and soil moisture.2 History of Aerospace Telemetry: One of the earliest documented uses of telemetry (TM) occurred in the United States (U. the variable was transmitted as a function of electrical pulse timings rather than voltage or current. precipitation and leaf wetness data for disease prediction models. space. retail businesses. TELEMETRY APPLICATIONS Telemetry applications and its usage are highly visible in the areas of agriculture. The current type system involved using a “balanced system” in which a current in the circuit connecting the point of measurement to the point of display and applied force to an armature. These early TM systems were used by the electric power companies to monitor the distribution and use of electricity. wind speed. the balancing occurred at the receiving end.) in 1885. such as air temperature. The first TM systems were extensively voltage or current type systems only and didn’t involve radio frequency (RF) usage. Following World War I (WWI). defense. and were called supervisory systems because of their monitoring abilities. the postwar WWII years and the advent of the missile age have resulted in a phenomenal increase in TM usage. Instant data allows the . The voltage system also worked on a “balanced” method. patent was granted for a telemetry system as a result of the invention of the telegraph and later the telephone. TM data was transmitted by the electric power lines themselves. IL. In that year. however. most modern telemetry systems use radio transmissions to span substantial distances. due to the expansion of public utilities. and resource exploration systems. The voltage generated was a function of the quantity of telemetry to be measured and occurred at the transmitting end of the circuit.1 Agriculture and Telemetry Usage: Growing crops today is a very hightech competitive business. wired telemetry systems were just starting to become more prolific in the U. Following WWI. relative humidity. This method allowed the information to be transmitted without serious loss of fidelity through circuits that were “less than perfect”. the line current was reduced to zero by a self-balancing instrument that generated a voltage to “buck out” the current in the line. Although electrical telemetry systems are still in use. the bucking voltage was equal to the transmitted voltage within the sensitivity of the balancing instrument like combination. In the pulse-type TM. especially in the area of flight testing of aircraft and munitions. and resource exploration systems in the U. Water management applications use telemetry for automatic meter reading. Engineers need critical system parameters in order to analyze and improve the performance and safety of the system. REQUIRED TELEMETRY EQUIPMENT The minimum equipment required for a radio telemetry system consists of signal conditioning equipment.6 Telemetry and Water Management: Telemetry remains indispensable in water management applications. This telemetry data eliminated the need for excessive trips by vending machine service drivers to see what items needed to be restocked before bringing the inventory inside. oil rigs. and record-keeping necessary for safe. and spacecraft because TM allows automatic monitoring. the monitoring of rainfall. active RFID tags are available that periodically transmit telemetry to a particular base station. satellites and aircraft because the system might be destroyed after or during the missile test. However. 2.S. and water quality. space. Telemetry systems provide vital data in the development phase of missiles.3 Telemetry Usage in Medicine: Medical applications for telemetry include the use of biotelemetry in coronary care units for patients at risk due to abnormal heart activity.2 Telemetry Usage in Retail Business: Retailers make use of radio frequency identification (RFID) tags to track inventory and prevent shoplifting. and is the enabling technology for large complex systems such as missiles.agriculturalist to understand the progress of water into the soil and towards the roots. The left portion of the block diagram depicts the block diagram components required to transmit the link while the right side of the . subcarrier oscillator equipment. 3. Space agencies such as National Aeronautics and Space Administration (NASA) use telemetry to collect data from operating spacecraft and satellites. these data parameters would often be unavailable to the engineer. 2. and a ground station1 as shown in Figure 1. recording and transmitting devices and a diagnostic data log of the patient's condition that is generated with the transmitted device. alerting. chemical plants. and use equipment surveillance for leak detection in distributed pipeline networks. Animals under study may be fitted with instruments ranging from simple tags to cameras. groundwater characteristics. Real time satellite telemetry data provides continuous monitoring for military activities. 2. some retail businesses used telemetry equipment to communicate vending machine sales and inventory data to a route truck and headquarters. an RF link. efficient operations. 2. groundwater monitoring. such as in hydrometry. The ability to have realtime data allows quick reaction responses in the field. In 2005.. Biotelemetric devices are also used by nurses to monitor the patient’s acute or dangerous condition.5 Wildlife Management and Telemetry: Wildlife monitoring utilizes animal telemetry. Most of these RFID tags passively respond to RFID readers and send data to the cashier. 2. to global positioning system (GPS) packages. These patients are outfitted with measuring. Without telemetry.4 Telemetry Usage in Defense: Telemetry data systems enable defense. with transceivers to provide position and other basic information to scientists and stewards. monitoring species at the individual level. The reactance-controlled oscillator uses variable reactance type transducers. Based upon test and datagathering requirements. Figure 2: Telemetry Transmitting System Block Diagram Figure 3. and phase-sensitive Figure 3: Telemetry Receiving Block diagram Figure 1: Telemetry Link Block Diagram The below figure depicts block diagram components for a basic signal source. causes the oscillator frequency to drift accordingly. The proper RF link to communicate with the test article and data collection stations determines component selection. is one way to eliminate the use of signal conditioners. where one or more of the arms of the bridge changes resistance. analog magnetic recorder. AC amplifiers. and data display. depicts block diagram components for a basic preamplifier. signal conditioning circuitry. utilizing VCOs and resistancecontrolled oscillators where needed. 3. flow meter . altitude. strain gages can be still be excited with a DC voltage and the outputs can be used to modulate voltagecontrolled oscillators (VCO). If system calibrations become a problem. telemetry receiver.2 Sub-Carrier Oscillator Equipment: A sub-carrier oscillator. demodulators. The VCOs are available in numerous types of modulating equipment and come in many customizable configurations for both vacuum tube and transistor variants. the TM engineer determines the necessary TM-measuring system. with a transducer designed into the oscillator circuit itself. Transducers of this type are installed commonly in flight test operations requiring pressure. data synchronizer. signal conversion and multiplexing. 3.diagram depicts the block diagram components for the ground station. A resistancecontrolled oscillator used in a strain gage bridge circuit. and aircraft positioning to be measured. converters. Commonly used signal conditioning equipment includes DC amplifiers. regardless of the transducer output signal characteristics. and transmission circuitry.1 Signal Conditioning Equipment: A signal conditioner device converts the output of the transducer into a more suitable form for modulating the sub-carrier oscillator. Any change in inductance within the transducer will cause a proportional change effect in the oscillator frequency. If an airborne TM system is in relatively close proximity to a particular receiving station. This FM-type transmitter is called a crystal stabilized transmitter because a crystal is used to determine the necessary frequency and stabilize it. specific antennas. are required to provide adequate signal strength at the receiving station throughout the flight path of the test . and receivers to make the RF link complete. intermediate amplifiers. Most of the transmitters are either frequency modulated (FM) or phase modulated (PM). and is often called crystal controlled modulation. or rock. including air. the composite signal from the output of the sub-carrier oscillators and from the output of the mixer amplifier. routs the information to a set of sub-carrier discriminators and to a magnetic tape recorder in the telemetry station itself. are used to modulate the transmitter itself. the modulation is accomplished by shifting the carrier frequency. space. and space exploration. such as in power distribution systems and pipeline systems.3. called the sub-carrier multiplex. microwave systems may be used. such as transmitting and receiving. the multiplexed signals are usually recorded on one track of the magnetic tape recorder for flight test to perform subsequent data reduction. which is the recovered sub-carrier multiplex.3 Radio Frequency (RF) Link: When a particular type of sub-carrier oscillator is used in an FM/FM type telemetry system. the outputs from the oscillators must be combined into a composite signal. a free space path to radiate. Power line and wire line carriers cannot be used for aerospace telemetry because of telemetry distance limitations. wire line carrier. which is then able to modulate the transmitter carrier signal. which are considered a class of electromagnetic waves . water. The receiver output.Antennas convert radio frequency electrical currents into electromagnetic waves and vice versa. As mentioned earlier. these industrial telemetry systems often use a power line carrier. or an antenna system. This particular type of telemetry system is extensively used for industrial applications. preamplifiers. 3. however. and microwave systems. PM transmitter modulation is accomplished by performing a phase shift of the transmitter frequency.4 Transmitters: One of the most important components in the RF link for aerospace telemetry is the use of transmitters. multi-couplers. The modulated carrier signal transmits to a receiving radio station. wireless local area network (LAN). 3. In addition. frequency mixers. radar. For a FM transmitter. soil. Television broadcasting. which is generated within the transmitter. the two main TM concerns for engineers are noise and errors. demodulators. However. for short distances. Antennas transmit and receive RF via numerous mediums. After the RF link has been established. point-to-point radio communication. RF amplifiers. a cable installation provides the multiplexed output of the sub-carrier oscillators directly to the inputs of the discriminators. These antennas. Antennas are used in systems such as radio. The signals of interest are then separated at this time by the discriminators and then reconverted to the form in which they appear at the output of the transducers in an airborne system.5 Antennas: An antenna is a transducer designed to transmit or receive telemetry radio waves. The RF link in an aerospace telemetry system also requires transmitters. at specific frequencies. if the distance between the transmitting station and the receiving station is too great for direct cable linkage. Preamplifiers are required when acquiring telemetry data due to a large attenuation in the telemetry signal through free space itself. If the intent is to overcome only cable losses. consists of using anything that will pass current in one direction only and this current is considered to be rectified. A preamplifier installation. all within the receiver itself. The envelope detector may be in the form of a single diode. The pre-amplifier maintains certain signal strength and signal level compatibility. Another type of FM receiver is the crystalcontrolled FM receiver.vehicle. Each output of the multi-coupler routes to an FM-type receiver. 3. This type of FM receiver requires the selection of an appropriate crystal to tune the incoming telemetry signal. The carrier wave or carrier.8 Demodulators: A demodulator is an electronic circuit used to recover the information content from the carrier wave of a signal. or may be more complex.6 Receiver: A receiver is an electronic device or circuit that receives telemetry signals from an antenna and converts these signals into meaningful data. which is modulated (modified) with the input signal for the purpose of conveying information to be transmitted. based on receiver input requirements. a very simple method of demodulation. . is a waveform. The preamplifier can provide amplification of the antenna output signal before there is any signal loss generated in the cable itself. Long cables running between the receiver and the antenna cause large losses to receiving systems. is used to amplify the antenna output signal and overcome excessive cable losses. The sub-carrier composite signal is a replica of the signal which was used to modulate the transmitter in the telemetry package. 3. The amplitude modulated (AM) signal encodes the information onto the carrier wave by varying its amplitude in direct sympathy with the signal to be sent. the preamplifier installs in very close proximity to the antenna. A modem device uses both a modulator and a demodulator.7 Preamplifiers: A preamplifier is an electronic amplifier which precedes another amplifier to prepare an electronic signal for further amplification or processing6. the signal is ready to be transmitted from one test vehicle to a receiving station only after the modulated carrier achieves sufficient amplification. controlled from within the receiving station itself. The FM receiver is usually a continuous-tunable unit that can be tuned to any frequency within the telemetry band being utilized. At least two methods are used to demodulate AM signals: (1) use an envelope detector or (2) use a product detector. The carrier wave functions at a much higher frequency than the baseband (information containing) modulating signal. The telemetry signal is amplified and the sub-carrier composite signal is separated from the detected carrier signal. usually a sinusoidal waveform. the use of a multi-coupler would not be necessary. If only one receiver is required. and have self-regulating power supplies. 3. The envelope detector. at or near the receiving antenna. through the use of frequency-discriminating network and filter circuitry. such as navigationalposition information8. The main advantage of using this particular preamplifier configuration is that it provides a higher signal-to-noise ratio. Preamplifiers configured for this purpose usually mounts in some type of weatherproof enclosure. such as voice or data. The receiving antenna output signal expects high enough power to overcome any degradation due to signal attenuation or signal loss between the antenna and the receiver itself. For instance. uses these particular type telemetry ground stations to support the Advanced Medium-Range Air-to-Air Missile (AMRAAM) program. it is necessary to incorporate an automatic calibration procedure into the telemetry process. Eglin AFB. and available funding. in many cases. The test station usually monitors and simulates “weapon fly out” data. The product detector multiplies the incoming signal by the signal of a local oscillator with the same frequency and phase as the carrier of the incoming signal. mentioned earlier. safety. the stations are usually minimally configuration with rack-mounted test equipment at a remote location near the intended target. when employing telemetry applications involving aircraft and missiles. However. 3. Notional Telemetry Ground Station. Telemetry calibration is discussed in the next section in more detail. such as the interference between irregularities in bearing surfaces. depicts a notional ground telemetry station setup. although if the phase cannot be determined.Many natural substances exhibited this rectification behavior. The results of a measurement may then be “corrected” in accordance with the calibration. If the ground station is used for aircraft telemetry programs. FL. After filtering the original audio signal will result. There are many possible telemetry ground station configurations and the particular configuration really depends on how many data sources you choose to monitor. These telemetry ground stations are usually configured in prefabricated trailers are built using rackmounted equipment for easy equipment access. When telemetry ground stations are used for missile or munitions test programs. shown on the following page. as with any measurement process. 4. Systematic errors are those errors that can be eliminated by some calibration procedure or other form of compensation.9 Telemetry Ground Station: The telemetry ground station contains the RF equipment necessary to receive the telemetry data (receivers. receiving antenna. exploits the simplicity of the modulation to produce an AM receiver while using very few parts. this station must contain sufficient equipment to process and display those data signals required for realtime monitoring. This station only serves to receive the composite telemetry signal from the receiver and stores TM data on a magnetic tape for further processing at another subsequent location. If these “drifts” are slow enough. which helps explain why it was the earliest modulation and demodulation technique used in radio. it’s not practical to . Figure 4. the thermal motion of electrons in conductors.). This method will decode both AM and singlesideband (SSB). and other processing and recording equipment to monitor telemetry data. etc. a more complex setup is required. In many cases there are “zero drifts” due to things such as temperature changes. preamplifiers. test requirements. In radio telemetry. such as monitoring F-16D aircraft operational flight programs (OFP). Systematic errors may be calibrated out by suitable methods. The crystal set. or the shot effect of electrons in vacuum tubes. such as an RF calibration test. they may be corrected for by performing frequent automatic or manual calibrations. Random errors result from the superposition of unrelated events. to name a few. TM CONCERNS: NOISE AND ERRORS One of the main concerns when using telemetry data is the possibility of introducing excessive noise and errors into the TM data stream itself. Errors are inherently present to a greater or lesser degree. These errors may be classified as either systematic or random. It’s impractical to load the member by a known amount during flight. but can’t be eliminated the same way that systematic errors can be eliminated. Random errors. by averaging processes. A good example of this technique is the use of a strain-gage bridge used to measure bending in a structural member. can also be reduced by good design. In this case. or noise. or using wide-band modulation methods. The resulting calibration is used to correct zero drifts and changes in sensitivity of the subsequent parts of the system. drifts in zero and sensitivity of the subsequent remaining parts of the system will become more detectable and easier to correct.vary the physical variable at the input of a particular channel by a known amount Fig 4: National Telemetry Ground Station during flight test. a calibration variable is inserted at the first subsequent feasible point in the system. In this case. The reason this isn’t possible is because all physical systems have . and then inserting known fractions of the bridgedriving voltage into the system at this point. If this calibration bridge circuit is designed properly and the precise location of the bridge elements is known. drifts in zero and sensitivity of the bridge become more unlikely. but doesn’t give information on changes in the bridge circuit. so the calibration is frequently achieved by disconnecting the output of the strain-gage bridge using a relay. transducer calibration. The instrumentation engineer should become very familiar with the piece of equipment and the techniques used by the manufacturer to prevent “unnecessary calibration errors”. If manufacturing performance deviations are present. images. environmental errors and inherent equipment errors. and immediately after the actual test. electro-optical methods. certain temperature effects on a piece of equipment can be compensated for or calibrated out. or standardize systematically the graduations of a quantitative measuring instrument. Engineers test and calibrate individual components in a suitable laboratory before installing the system to ensure that data is of the highest possible quality. Environmental errors are as difficult to cope with as inherent equipment errors. and friction in pickup instruments. shaft power. the engineer subjects the telemetry system to a carefully conducted end-to-end calibration checks just before. For instance. For example. calibration is defined as one of three different types. and cases. data system calibration. or physical end-to-end calibration. 5. humidity. direct wiring.” A telemetry system measurement “begins with the sensing of the item to be measured using a transducer located either on a test vehicle or at a remote test site. to name a few. dry friction.1 Calibration Types: For illustrative purposes. techniques. the engineer may end up defining a new transfer function for that unit. As such. temperature. position. Other temperature effects may be considered random effects. Many environmental errors are also systematic. crosstalk in multi-channel systems. drifts in zeros and gains. adjust. Many engineers stop after performing a transducer calibration and then combine the . Additionally. reset the device to conform to the original transfer function.” This section introduces instrumentation engineering guidance on how to address general calibration methodologies. strain. and phase angle. successive calibrations may indicate upcoming failures. displacement. torque. flow. Telemetry systems can be interconnected by radio links.2 Transducer Calibration: Transducer calibration focuses on the transducer input output relationship. or other combinations. time. TELEMETRY CALIBRATIONS To calibrate means “to check. these errors are divided into two broad groups. angular rate. or in some cases. and are the result of dry friction. Each of these measurements may require a different calibration technique. temperature changes. After manufacturing equipment and calibration techniques are known. corrosion. The transducer manufacturer usually performs a unit calibration in their laboratory. frequency. 5. and other environmental factors. In either case. Environmental errors are errors that arise when a particular piece of equipment is subjected to acceleration. such as the relative expansion of components in sliding contact with each other. to name a few. such as photographic emulsions. the engineer should then perform an in-house calibration on the individual transducer to verify the accuracy of the manufacturer’s transfer function. acoustics. velocity. pressure. during. or other effects such as the granular nature of electric currents. 5.performance limited by random effects. the instrumentation engineer uses many types of transducers to make many physical measurements of acceleration. The calibration ends at a data storage or display device located at a receiving test site. heat flux. video. Inherent equipment errors are caused by such factors as noise in the RF radio link. an instrumentation engineer should become very familiar with the piece of equipment and the techniques used by the manufacturer to prevent “unnecessary calibration errors”. . 19 An end-to-end mechanical calibration means a full calibration of the instrumentation from the actual physical input. An end-to-end calibration verifies the measurement system characteristics and is per-formed by engineers after installing the measurement system in the test article. This method provides a calibration estimate under the assumption that the engineer precisely knows all the transfer characteristics of the wiring and other signal conditioning between the transducer and the data storage system. A minimum data system calibration should then be performed after mounting the transducer on the test article. also called mechanical end-to-end calibration. allows the engineer to identify and correct any potential problems early in test. A calibration source stimulates the transducer and the instrumentation engineer monitors the signal entering the data collection unit to ensure the calculated value matches the actual system transfer function. to the output. rather than physically stimulating the transducer’s sensing device. This can be accomplished by simulating an excitation of the transducer. It is highly recommended that end-to-end calibrations be performed before the test experiment. Data system calibration simulates the desired item to be measured. As stated earlier. focuses on the relationship between the physical input and measured output throughout the entire measurement system. after the test experiment is completed. such as inaccessible or glued transducers. and is the best method to ensure the collection of valid data. but one bad connection invalidates the data. such as phase and wiring errors. The most important consideration for making valid engineering measurements is to determine how the transducer operates in the actual test environment with all signal conditioning attached. such as is often accomplished for strain gages. 5. The end-to-end calibration checks the measurement system. where the analog or digital signal will normally be analyzed. Manufacturer usually performs a unit calibration in their laboratory. Installation constraints. by using a shunt calibration resistor to simulate a change in resistance of the strain gage. and before the instrumentation system is removed.4 Physical end-to-end Calibration: Physical end-to-end calibration. The transducer should be calibrated while connected to the same signal conditioning equipment in the laboratory as it would be used on the actual test article. although this configuration is not always feasible.3 Data System Calibration: Data system calibration simulates or models the input of the entire measurement system. 5. Inserting a simulated transducer signal into the system verifies all signal conditioning transfer function predictions and simulates transducer excitation by its physical input. to the transducer. It should be noted that relying solely on transducer calibration is too risky for collection of valid data on an experiment or test. The engineer assumes that all wiring and signal conditioning will function as designed. including wiring and connectors installed on the test article. often mean that a data system calibration is the best that an instrumentation engineer can achieve to ensure the acquisition of valid data.transducer’s transfer function mathematically with the data system signal conditioner’s transfer functions. The choice as to which IRIG serial time code to use is based on the user’s needs..000 PPS rates are usually overkill for most applications. missile tracking systems. (2007) 46th Test Wing. 8 References [1] Types of Modulation.wsu. These digital codes are typically amplitude modulated on an audio sine wave carrier or transmitted as fast rise-time TTL signals. and supportability of that particular IRIG standard when performing tests. For instance. ground tracking networks. 7.2 IRIG B: The Choice Standard: Although the six standardized time codes have been in existence for quite some time.6. [2] Hydrometry-Wikipedia. These serial formatted time codes have the following rate and count interval: IRIG-Type Rate Count Interval IRIG-A: 1.1 Summary of Different IRIG Formats: There are mainly six different IRIG formats that standard test range areas readily support. Also. retrieved from http://en. retrieved from http://cbdd.000 PPM 0. It gave some telemetry applications and introduced the telemetry equipment requirements. The main difference between each IRIG format is the rate. and represents the rate at which data is correlated. data system. IRIG-B. IRIG-E. FL. Standardization of time codes is necessary to ensure system compatibility among the various ranges. and outlined some telemetry concerns. It also discussed signal conditioning and sub-carrier oscillator equipment.htm. spacecraft and missile projects.000 or 10. Sr. and IRIG-H. IRIG-D. [3] Lalik. Serial formatted time codes are used to efficiently interface a timing system output with the user system. CONCLUSION This paper presented telemetry and provided a brief history of how telemetry came about.org/wiki/Hydrometry.” 6. and the count interval. and international cooperative projects. require time-of-day and year information to properly correlate data with time. and physical end-to-end calibrations.wikipedia. millisecond.000 PPS 1 ms IRIG-B: 100 PPS 10 ms IRIG-D: 1 PPM 1 minute IRIG-E: 10 PPM 0. data reduction facilities.1 ms IRIG-H: 1 PPS 1 second 6. one or ten pulses per minute for a rate is usually too slow for many applications and 1. and other data handling systems. which is usually in seconds. “modern electronic systems such as communication systems. or minutes. the six IRIG formats currently available are IRIG-A. Jay M.edu/kewlcontent/cdoutput/T R502/page21. The IRIG-B serial time code is primarily used because many instrumentation applications can sufficiently use the 100 PPS rate and usually a count interval of 10 ms is more than enough to accurately analyze the telemetry data. Eglin AFB. IRIG-B is primarily chosen as the “format of choice” because of its 100 PPS rate and 10 ms count interval. the most commonly used IRIG format used today is the IRIG-B serial time code format. Flight Test Engineer. such as noise and errors. WHY USE DIFFEENT IRIG FORMATS? Today. . the fidelity of data being analyzed.1 second IRIG-G: 10. usually in pulse per second (PPS) or pulse per minute (PPM). and presented ways to minimize these errors using transducer. IRIG-G. [10] White Sands Missile Range. Test Methods for Telemetry for Telemetry RF Subsystems. Telemetry Systems Radiofrequency (RF) Handbook. Prentice-Hall.htm. NJ [7] Stiltz. Point Mugu. Inc. California. [8] White Sands Missile Range. Harry L. Handbook. Inc. Inc. .[4] Nichols. Radio Telemetry. [5] Pacific Missile Test Center. Inc. NJ. Document 118-02. Myron H. Lawrence L..army.. Prentice Hall Publishing. Test Methods for Telemetry Systems and Subsystems.. Harry L. Instrumentation Engineers Handbook. (1961). Prentice-Hall. Aerospace Telemetry-Equipment Telemetry Applications Requirements. RCC OnLine Documents. Document 120-01. and Rauch. Volume 2.wsmr. [6] Stiltz. Prentice Hall Publishing. RCC OnLine Documents. Document 121-06. Englewood Cliffs. RCC OnLine Documents.mil/rcc/ manuals/118v2/ind ex118vol2. Aerospace Telemetry.. [9] White Sands Missile Range. Vol 2. retrieved fromhttps://wsmrc2vger. (1956) John Wiley & Sons. John Wiley & Sons. (1961). NY and London. Englewood lifts.