Mohanty, Nirode C.; The Aerospace Corporation (International Foundation for Telemetering, 1985-10)
      A demand access Satellite Communication System for multiple users has been analyzed. A number of channels, m 1, of each satellites are necessary to coordinate the self-served users to allow access to a satellite having s channels. m depends upon traffic intensity and number of top priority users. A waiting time period for a Poisson arrival and exponential holding time M/M/s system for “preemptive resume” discipline has been derived. There is a significant reduction in waiting time in accessing the channel and in transmission time over other access schemes. There is no waiting time for a top priority user, either in accessing the channel or in transmitting its messages, when the appropriate number of order wires is used.
    • Autonomous Control and Data Acquisition for Advanced Satellite Systems

      Turner, Tim; Gulton Industries, Inc. (International Foundation for Telemetering, 1985-10)
      Autonomous operation is rapidly becoming a requirement for most new spacecraft systems. An autonomous spacecraft greatly simplifies the ground station processing and monitoring requirements, freeing ground station capabilities for other important tasks. The T2C2 (Telemetry, Timing, Command and Control) System has been conceived and architected to facilitate spacecraft autonomy. The T2C2 architecture is ideally suited for onboard closed-loop control, redundancy management, housekeeping and other autonomous functions. This paper provides an overview of the T2C2 architecture and its applications in the design and implementation of an autonomous spacecraft.

      Ng, Wai-Hung; The Aerospace Corporation (International Foundation for Telemetering, 1985-10)
      For space monitoring systems, it is necessary to compress the transmitted data to minimize the power and bandwidth requirements. Although there are many data compression techniques, here we will only discuss the sample reduction technique because it is the best candidate for cases when the signal contains many redundant samples and the resolution requirement for the reconstructed signal is very high. In this paper, we introduce a new code to further reduce the compressed signal data derived from the sample reduction technique. The main advantage of this approach is that we can minimize the transmission data rate without requiring a priori knowledge of the signal distribution property. In addition, it can also reduce the buffer size requirement. Examples are given for clarification and discussion.

      Nardou, Alain; Telemetering and Systems Department (International Foundation for Telemetering, 1985-10)
      INTERTECHNIQUE which manufactures the TM 77.600, I.R.I.G. format decommutator, has had to extend the PCM message acquisition performance range to the DANIEL format, and has thus developed the TM 78.420. The TM 78420, capable therefore of acquiring both DANIEL and IRIG PCM messages, meets the requirements of the users of the Avions Marcel Dassault methods service telemetering station at Istres. This equipment provides for the acquisition and display, in different forms and in real time, of values of parameters contained in a PCM message. The following values can be displayed simultaneously on five cathode screens: - 128 parameters in analog form, bar-graph type - 32 parameters in digital form, in physical magnitudes. The values of 16 parameters can be restored in the form of analog voltages and those of four parameters in binary form. An operator terminal, consisting of a display console/alphanumeric keyboard unit, prepares the deswitching program and monitors the equipment in general. The system consists of the following subassemblies; - 4 analog display terminals designated as A, B, C, D - 1 alphanumeric terminal unit E - 1 logging rack - 1 operator terminal

      Hurd, William J.; Statman, Joseph I.; Vilnrotter, Victor A.; California Institute of Technology (International Foundation for Telemetering, 1985-10)
      Demonstration results are presented for a high dynamic GPS receiver. The receiver tested is a breadboard unit capable of tracking one simulated satellite signal in pseudorange and range rate. The receiver makes approximate maximum likelihood estimates of pseudorange and range rate each 20 ms, and tracks these observables using a third order filter with a time constant of 0.14 s. Carrier phase is not tracked, which eliminates the typical failure mode of loss of carrier lock associated with PLLs at high dynamics. The receiver tracks with pseudorange lag errors of under 0.06 m when subjected to simulated 50 g turns with 40 g/s peak jerk. Pseudorange errors due to receiver noise alone are approximately 0.6 m rms at a carrier power to noise spectral density ratio of 34 dB-Hz. The tracking threshold SNR is approximately 28 dB-Hz, which provides 12 dB margin relative to the 40 dB-Hz that occurs with minimum specified satellite signal strength, 3.5 dB system noise figure, and 0 dBi antenna gain.

      Zhou, R.; Mavretic, A.; Boston University College of Engineering (International Foundation for Telemetering, 1985-10)
      This paper will describe the design of a quaternary memory cell and a quaternary shift register. The concept used here is based on multiple-valued logic algebra, which can be extended to a design of other high radix memory cells and high radix shift registers. A comparison of the quaternary memory cell and quaternary shift register with its binary counterpart will be discussed. The reduction of device counts and interconnections in quaternary systems promisses a good future in digital signal processing and communication network design realized by VLSI technology.

      Gauthier, Kathryn L.; Wright-Patterson Air Force Base, Ohio (International Foundation for Telemetering, 1985-10)
      The Advanced Range Instrumentation Aircraft (ARIA) is an airborne platform designed to receive, record, process, and retransmit telemetry data. This paper will provide a brief overview of ARIA capabilities and focus on a specially modified ARIA – the Cruise Missile Mission Control Aircraft (CMMCA). Currently utilized in cruise missile testing, CMMCA features on-board real-time display of telemetry data as well as remote command and control of the test missile.

      Sullivan, Arthur; Electro Magnetic Processes, Inc. (International Foundation for Telemetering, 1985-10)
      Over a decade ago the author developed a unique conically scanning tracking antenna feed (RADSCAN) with only one moving part and extremely high reliability. While the system had many advantages over single-channel monopulse (SCM), there were two disadvantages: one was weight due to the drive motor; the other was the fact that the scan speed was constant. EMP is just completing the development of a conscan tracking feed which is pneumatically driven (Pneu-Scan) - thus eliminating the heavy electric drive motor. Since most telemetry tracking antennas require a dehydrator/pressurizer for environmental reasons, no additional drive power is required to scan the feed since the pressurized air from the dehydrator system is used to drive the feed. In addition, the scan speed is proportional to the continuously varying pressure. If increased reliability is required, then redundant dehydrators can be used. The feed system has only one moving part constructed from graphite fiber that weighs less than an ounce. The feed is driven by a small lightweight impeller. An S-band tracking feed of this design is less than five inches in diameter - as compared to 12 inches for an SCM feed. It is also considerably lighter than an SCM feed. Decreased aperture blocking - by more than a factor of two enhances sidelobe levels and maximizes gain. The new feed illuminates a lightweight 5-foot diameter graphite-epoxy constructed paraboloidal reflector positioned by an elevation-over-azimuth pedestal. Both the elevation and azimuth assemblies of the pedestal are constructed of graphite fiber composite material - which greatly reduces both weight and cost as compared with the conventional steel or aluminum construction. An inflatable rotodome surrounds the elevation assembly and rotates with azimuth. The rotating sphere has minimum wind induced torque thereby minimizing the required drive power. The weight of the entire system is less than 135 pounds - yielding an extremely light weight, low cost, versatile two-axis telemetry tracking system.
    • Flight Test Instrumentation System FTIS for Type-Certification of the Indonesian Aircraft CN 235

      Klewe, Hans-Joachim; Soelaiman, Adi Dharma; DFVLR, Institute for Flight Mechanics, Braunschweig/Germany; PT. NURTANIO, Bandung/Indonesia (International Foundation for Telemetering, 1985-10)
      Certification of an Aircraft necessitates ample instrumentation equipment to get all the data needed. The Flight Test Instrumentation System for the Indonesian Aircraft CN 235 (Fig. 1) does not consist only of the necessary data acquisition and evaluation systems, but includes moreover all the subsystems which are needed in flight testing like airborne- and ground-calibration systems, video and camera-installations etc. The Mobile Ground Station is housed in 14 shelters including a power-station and can be seen as a selfsupporting system. Design and procurement by DFVLR assisted by Indonesian engineers as well as assistance through DFVLR in Indonesia was a first leading project in the course of the establishment of an Indonesian Flight Mechanics Laboratory FML. After service in Type Certification of the CN 235 the Flight Test Instrumentation System described will have a wide application range for future projects. To get a staff of engineers scilled in the art of flight-testing a training program for 10 Indonesian engineers was conducted by DFVLR, so that there are experts to operate the system in Indonesia. Since 1984 the Flight Test Instrumentation System is in use in Bandung or Jakarta resp.

      Mohanty, Nirode C.; The Aerospace Corporation (International Foundation for Telemetering, 1985-10)
      An adaptive equalizer, based on a minimum mean square error criterion, has been derived for the purpose of extracting PSK signals transmitted through an unknown and asymmetric channel. The weights of the equalizer are obtained by using a simple formula containing the transform of the parallel channels. The performance of the equalizer is expressed in terms of the variance of the estimation error. The error is shown to be much less than that of the direct demodulated data.
    • An Expert System for Satellite Control

      Pazzani, Michael; Brindle, Anne; The Aerospace Corporation (International Foundation for Telemetering, 1985-10)
      As on-board satellite systems develop increased sophistication and autonomous capabilities, failures become fewer, but the diagnosis of the remaining failures becomes more complex. In addition, autonomy requirements for space vehicles are being issued along with requirements for reduced staffing of ground stations. Thus successful groundbased fault handling in the future will require greatly increased automation of fault detection and diagnosis. This paper investigates the use of an expert system as a ground system component for diagnosis. The diagnostic cycle of the system is presented, along with requirements for its knowledge base. The results of implementing the design to diagnose part of a satellite attitude control system are given. Knowledge acquisition for this problem centered on the generation and analysis of terminal displays of telemetry which look much like strip charts. Correct diagnosis by the expert system derived from the use of extensive telemetry analysis, operations and satellite status databases, and satellite modeling.

      Aure, Jean Marie; Telemetering and System Department (International Foundation for Telemetering, 1985-10)
      It is difficult to transmit directly the data circulating on a 1553-B bus by microwave link during a missile test, given that it is not a synchronous message. For the ANS missile the AEROSPATIALE tactical missile division has decided to include the 1553 message in a PCM message to IRIG standards. In view of the asynchronism between the traditional telemetering data and the bus message it has been necessary to develop a specific controller providing the interface between the bus and the IRIG PCM. This controller performs the functions of synchronization, encoding, structural analysis of message, adaptatin of the input speed to the PCM rate and also dating of the data. Moreover, during tests on the missile, it is necessary to process the bus data on the ground. A conventional decommutator, although suitable for the usual analog channels, cannot be used in real time. It is therefore been necessary to develop equipment providing on the ground the reconstitution of a 1553 bus that can be processed by ordinary standard equipment. After synchronizing and sorting the data in the IRIG format the equipment creates three types of messages corresponding: to the missile message, to the dating and to the message found erroneous during acquisition on board.

      Vorce, Richard G.; Fairchild Weston Systems Inc. (International Foundation for Telemetering, 1985-10)
      The unit to be described differs from present tunable discriminator products chiefly because it is designed to simultaneously demodulate all the subcarrier channels in a frequency division multiplex. In addition the demodulated output data is presented in digital format that is compatible for direct computer entry. The discriminator implementation techniques will be discussed at the block diagram level. Particular emphasis will be given to the use of “Finite Impulse Response” filters and also to the internal tape speed compensation process.
    • International Telemetering Conference Proceedings, Volume 21 (1985)

      International Foundation for Telemetering, 1985-10

      Mohanty, Nirode C.; The Aerospace Corporation (International Foundation for Telemetering, 1985-10)
      The performance of a code tracking loop for a spread spectrum signal can be severely deteriorated in the presence of an interference signal. The interference signal is modeled as a signal with the same code but with a different delay and carrier frequency. The variance of the tracking delay error is derived in terms of loop bandwidth, chip duration, the interference and signal power and bandpass filter bandwidth and the power spectral density of the additive Gaussian noise.

      Shaw, Harold; Lawrence, Francis A.; New Mexico State University; Syndetix, Inc (International Foundation for Telemetering, 1985-10)
      In early 1981, the Physical Science Laboratory (PSL) was tasked by the Air Force Geophysics Laboratory (AFGL) to develop a portable Pulse-Code Modulation (PCM) telemetry station that would acquire and support the higher PCM data rates from Ariestype rocket payloads. The station would have to provide real-time and near real-time calibration, prelaunch and launch test support to AFGL researchers involved in space vehicle probe analysis. The station would also have to utilize a flexible software system, transportable hardware, and be easily expanded to meet the continually growing and varied needs of the researchers.

      Mainguy, Jean Claude; Telemetering and Systems Department (International Foundation for Telemetering, 1985-10)
      The development of a ballistic missile or satellite launcher requires a great number of varied measurements distributed right over the missile. The PCM CANNES system is basically featured by its decentralized structure in which a programmable unit provides remote management, through a 1 Mbit/s digital link, of the peripheral units acquiring the data. This structure offers the advantages of modularity, flexible use and easy adaptation to specific requirements. A new unit in process of development, named UCDA, will considerably increase the performance of the system whilst ensuring perfect compatibility with the existing peripheral unit.

      Zimmerli, Dana W.; Elston, Steve; Magnavox Advanced Products and Systems Company; BDM Corporation (International Foundation for Telemetering, 1985-10)
      This paper describes the design and performance of a flexible data link system for test and training range communications. To support a wide variety of range applications, this data link provides variable length messages, participant store-and-forward relays, remote data stations, three modes of operation - TDMA, polled, and carrier sense, and a transmitreceive range of more than 80 miles. The data link is adaptable to different message rates and sizes to support different types of missions. For example, a high dynamics aircraft mission can be supported by two-way 400 bit messages from 25 aircraft 10 times per second; a tactical armor mission can be supported by two-way 200 bit messages from 500 participants once per second. The data link is designed with packet radio and pseudonoise spread spectrum techniques to combat common range communication problems such as multipath fading, host vehicle obscuration, coexistence, interference, and vehicle dynamics. Data link performance is presented to show the flexibility and adaptability to various range communication requirements.

      Ren, Li Ke; Beijing Research Institute of Telemetry (International Foundation for Telemetering, 1985-10)
      Generally, the data acquisition equipment used in space vehicles mainly consists of logic program control, multiplexer-encoder, output driver, power supply for dc conversion and so on. Today telemetry technology has been deeply concerned with computer science. So how to make the telemetry system more flexible and versatile and how to design a multiplexer-encoder (data collector or remote unit as is called in a programmable telemetry system) with good compatibility and powerful function has become one of the most important things of developing a new generation of telemetry system. In 1960s, most of the telemetry systems were of typical coded time-division multiplexing. The sampling program of this system is fixed and its bit rate and frame format are unvaried, so it is difficult for a system to accommodate the requirements of various kinds of measurements, especially when there are comparatively more parameters to be measured, and most of which are of slow-changing. As the sampling rate is designed in accordance with the upper-limited signal frequency that we need to measure, so the validity of the slow-changing data is very low. And onced the telemetry equipment has been developed, it is very difficult to change the sampling rate, the bit rate and the frame format. With the development of electronic devices, more devices can be integrated in a small chip, so the programmable telemetry had been pulled off in early 1970s. This article deals with mainly a few programmable multiplexer-encoders and microprocessor-controlled multiplexer-encoders used in our actual research work and applications.

      Wickham, M. E.; COMSAT Laboratories (International Foundation for Telemetering, 1985-10)
      An advanced microwave power leveling loop (MPLL) was conceived, designed, fabricated, tested, and used during spacecraft in-orbit testing. The primary function of the MPLL is to maintain constant RF power transmitted from an earth station antenna during spacecraft in-orbit transponder testing. The MPLL utilizes nonlinear analog electronics with flexible signal path routing under microprocessor control. It achieves a power control dynamic range of greater than 50 dB with better than 0.1 dB of control resolution. Power level step changes of 20 dB can be accomplished in under 10 ms. The MPLL is IEEE-488 bus controllable and is designed for use in automated in-orbit test systems to facilitate the measurement process and produce more repeatable results than have previously been possible. Measurements performed with the aid of the MPLL include transponder frequency response, group delay, gain, and saturation level. The system can also be operated in a manual mode, and utilizes state-ofthe-art human interfacing techniques such as a display/entry panel and a rotary encoder control knob. This paper describes the MPLL design process, including computer simulation work and breadboard testing. Performance and temperature chamber test results are presented for breadboard and manufactured units.