• Expert Systems in Data Acquisition

      McCauley, Bob; Telemetry Systems Operation (International Foundation for Telemetering, 1987-10)
      In an Independent Research and Development (IR&D) effort, the Telemetry Systems Operation (TSO) of Computer Sciences Corporation (CSC) sought to determine the feasibility of using Artificial Intelligence (AI) techniques in a real-time processing environment. Specifically, the use of an expert system to assist in telemetry data acquisition processing was studied. A prototype expert system was implemented with the purpose of monitoring F15 Vertical Short Take Off and Landing (VSTOL) aircraft engine tests in order to predict engine stalls. This prototype expert system was implemented on a Symbolics 3670 symbolic processor using Inference Corporation's Artificial Reasoning Tool (ART) expert system compiler/generator. The Symbolics computer was connected to a Gould/SEL 32/6750 real-time processor using a Flavors, Inc. Bus Link for real-time data transfer.
    • Data Handling System for IRS

      Rajyalakshmi, P. S.; Rajangam, R. K.; Digital Systems Division (International Foundation for Telemetering, 1987-10)
      The three axis stabilized Indian Remote Sensing Satellite will image the earth from a 904 Km polar - sun synchronous orbit. The payload is a set of CCD cameras which collect data in four bands visible and near infra-red region. This payload data from two cameras, each at 10.4 megabits per sec is transmitted in a balanced QPSK in X Band. The payload data before transmission is formatted by adopting Major and Minor frame synchronizing codes. The formatted two streams of data are differentially encoded to take care of 4-phase ambiguity due to QPSK transmission. This paper describes the design and development aspects related to such a Data Handling System. It also highlights the environmental qualification tests that were carried out to meet the requirement of three years operational life of the satellite.
    • International Telemetering Conference Proceedings, Volume 23 (1987)

      Unknown author (International Foundation for Telemetering, 1987-10)
    • Telemetry Bus Linkage with a High-Speed Ring Architecture: An Approach Analysis

      Nicolo, John M.; Aydin Monitor Systems (International Foundation for Telemetering, 1987-10)
      The growing complexity of space vehicle, aircraft, and missile test data analysis requiring larger data volumes and higher data rates, in conjunction with real-time analysis and display, calls for a new approach in telemetry system bus architecture. To meet these needs AMS developed the Mercury Bus, and a high-speed ring architecture capable of linking up to 7 Mercury Busses together without reducing targeted bus bandwidth of 6 MWPS. The Mercury Bus is a 48 bit parallel bus consisting of 32 data bits, and 16 "token" or address bits. It supports setup or real-time transfers between multiple master/slave modules within a chassis. The ring architecture consists of Bus Arbitrator, Repeater, Terminator Modules (BAT's) connected together by circular unidirectional read and write pipelines. The BAT arbitrates bus mastership, repeat's intra-chassis transfers and provides signal termination for the Mercury Bus. The pipelines relay bus transfers to successive chassis within the ring. This architecture currently supports up to 7 chassis or 112 modules per system. The ring architecture has met and exceeds initial design criteria with transfer rates measured in excess of 8 million words-per-second. It performs sustained high-rate data transfers while maintaining the data integrity and reliability associated with real-time telemetry. This architecture is well suited for systems with multiple input streams and high data processing requirements. Overall performance is attributed to the low noise characteristics of a controlled impedance backplane; implementation of module front end standardized bus interfaces; and the Bus Arbitrator, Repeater, Terminator module.
    • Trends in Space Station Telemetry Applications

      Muratore, John F.; Lyndon B. Johnson Space Center (International Foundation for Telemetering, 1987-10)
      Spacecraft telemetry systems have evolved from simple hardware devices to complex computer applications performing data acquisition and formatting tasks. This paper reviews the role of spacecraft computers in performing telemetry functions and examines computer based telemetry systems being considered for use on the NASA Space Station.
    • High Data Rate Reed-Solomon Encoding and Decoding Using VLSI Technology

      Miller, Warner; Moakis, James; Goddard Space Flight Center (International Foundation for Telemetering, 1987-10)
      Presented as an implementation of a Reed-Solomon encoder and decoder, which is 16-symbol error correcting, each symbol is 8 bits. This Reed-Solomon (RS) code is an efficient error correcting code that the National Aeronautics and Space Administration (NASA) will use in future space communications missions. A Very Large Scale Integration (VLSI) implementation of the encoder and decoder accepts data rates up to 80 Mbps. A total of seven chips are needed for the decoder (four of the seven decoding chips are customized using 3Fm Complementary Metal Oxide Semiconduction (CMOS) technology) and one chip is required for the encoder. The decoder operates with the symbol clock being the system clock for the chip set. Approximately 1.65 billion Galois Field (GF) operations per second are achieved with the decoder chip set and 640 MOPS are achieved with the encoder chip.
    • Space Shuttle Data Formatter DSI Model 7303 System

      Cardinal, Robert W.; Tremain, George F.; Decom Systems, Inc. (International Foundation for Telemetering, 1987-10)
      This abstract describes the hardware and software necessary for reserialization of asynchronous imbedded image data. The purpose of the DSI Model 7303 System is to reformat space shuttle imbedded (Payload Data Interleaver) PDI data. the system consists of two decoms, a DSI model 7303A and a DSI Model 7303B. The input to the 7303A box is 0I or NSP data (NRZ-L & CLOCK). The 7303A Frame syncs to the 0I or NSP data. The 7303A is front panel programmed to strip out only the imbedded PDI data and pass this data to the 7303B Decom. The 7303B Frame syncs to the PDI frame sync pattern. A second strip zone defines which words in the PDI frame get passed to the FIFO. A 24K byte ring FIFO Buffer is used to buffer data before reserialization for output. The serial output rate is a function of how many programmed PDI words per second are stripped out and the FIFO management status. The output bit rate is from a microprocessor controlled NCO. This system Makes possible real time video of Shuttle PDI data.
    • A Data Handling and Linking System for all of NASA's Near Earth Space Missions

      Hockensmith, R.; NASA/GSFC (International Foundation for Telemetering, 1987-10)
      A modularized data handling and linking system is evolving that will meet all of NASA's low earth orbiting space needs. The system is comprised of three major subsystems: (1) Data management (three networks; 300 Mbps to 20 Mbps, 20 Mbps to 3 Mbps, and 3 Mbps to 125 bps); (2) RF (antennas and microwave components); and (3) antenna control. Representative system components, approximately 70% of a total system, have been tested operating through the NASA Tracking and Data Relay Satellite System in May 1987. The modularized concept and data bandwidth transitions of the data management subsystem utilizes recently developed flight components along with developmental models that results in a system that is cost effective with a high level of performance and reliability. The system concept with performance data of key components will be presented.
    • Voyager Image Data Compression and Block Encoding

      Urban, Michael G.; California Institute Technology (International Foundation for Telemetering, 1987-10)
      Telemetry enhancement techniques implemented through flight software modifications and utilization of special flight hardware enable the Voyager 2 spacecraft to reduce telemetry transmission rates used at Saturn by over 50% for the extended mission to Uranus and Neptune with negligible loss in information return. Techniques employed include: * Parallel operation of the redundant Flight Data Subsystem (FDS) processors * Image Data Compressor (IDC) using noiseless (fully reconstructable) coding techniques * Reed-Solomon (RS) encoding of downlink telemetry.
    • An Implementation of Concatenated Coding Scheme on Indian Spacecraft

      Martin, Kamalini; Seshaiah, R.; Vasantha, E.; Rajangam, R. K.; ISRO Satellite Centre (International Foundation for Telemetering, 1987-10)
      A Concatenated Coding Scheme to provide an extremely 'clean' channel is suggested for onboard spacecraft telemetry system by the Consultative Committee for Space Data Systems (CCSDS). The outer code is a Reed Solomon block code and the inner, a Viterbi or Convolutional Code. The Gaussian channel are corrected by the inner code. However, the Viterbi decoder may introduce some burst errors. These are then corrected by the Reed Solomon decoder. The inner Viterbi code (K=7, rate 1/2) was developed and implemented for the first time in RSD2 (Rohini series) satellite. The outer code has not yet been implemented onboard spacecraft since the decoder has not been fully developed. However, the onboard encoding system (255,223) has been developed and tested. This paper describes the development and implementation of Viterbi encoder in RSD2 satellite along with its inorbit performance.
    • An Efficient Decoding Algorithm for Long Convolutional Codes

      Ng, Wai-Hung; Hsieh, Ning-Ning; The Aerospace Corporation (International Foundation for Telemetering, 1987-10)
      Optimum decoding of long convolutional codes is an attractive technique to achieve reliability of communication. However, conventional decoding algorithms are very sensitive to variations in operational conditions, and such algorithms are also difficult to adapt to high-data-rate systems. Based on distance properties of code and pattern analysis of test-error sequences, a new decoding algorithm is derived that does not have those disadvantages.
    • Effects of Co-Channel Interference with Frequency Offset on PSK Signals

      Raghavan, Srini; The Aerospace Corporation (International Foundation for Telemetering, 1987-10)
      The sharing of C-band between microwave terrestrial and satellite communication systems invariably introduces interference from one system into the other. Such co-channel interference becomes even more important in satellite receive stations with smaller antennas and must be minimized to achieve system performance objectives. In this paper, co-channel interference due to two TD2 (FDM/FM) carriers into a satellite receive system, receiving binary phase-shift keyed (BPSK) signal, is considered. It is shown that the frequency offset of the TD2 carriers from the BPSK carrier can be used to minimize co-channel interference effects. Equations are given which compute the bit error rate (BER) of BPSK signals in the presence of an interfering unmodulated carrier. They are followed by some results due to TD2 carrier interference.
    • New Concepts in PCM Encoding

      Yun, Paul M.; Omnitek, Inc. (International Foundation for Telemetering, 1987-10)
      The Pulse Coded Modulation (PCM) Encoder Systems used in telemetry have gained enormous flexibility for various applications because the input data channels and frame sync codes are programmable via the EEPROMs or UVEPROMs. The firmware in the current PCM Encoder Systems can be readily tailored for a specific application to monitor numerous types of analog channels, as well as digital channels. However, the current PCM Encoder Systems require several types of strap options which dictate not only a limited choice of gains and offsets, but also a fixed choice of the premodulation filter characteristics. The brain of the 1000 PCM Encoder is the Digital Signal Processor (DSP) which eliminates the fixed premodulation filter characteristics via digital filter functions, and also eliminates strap options via general purpose microprocessor functions.
    • Telemetry Handling on the Space Station Data Management System

      Whitelaw, Virigina A.; NASA - Johnson Space Center (International Foundation for Telemetering, 1987-10)
      Traditional space telemetry has generally been handled as asynchronous data stream fed into a time division multiplexed channel on a point-to-point radio frequency (RF) link between space and ground. The data handling concepts emerging for the Space Station challenge each of these precepts. According to current concepts, telemetry data on the Space Station will be packetized. It will be transported asynchronously through onboard networks. The space-to-ground link will not be time division multiplexed, but rather will have flexibly managed virtual channels, and finally, the routing of telemetry data must potentially traverse multiple ground distribution networks. Appropriately, the communication standards for handling telemetry are changing to support the highly networked Space Station environment. While a companion paper (1. W. Marker, "Telemetry Formats for the Space Station RF Links") examines the emerging telemetry concepts and formats for the RF link, this paper focuses on the impact of telemetry handling on the design of the onboard networks that are part of the Data Management System (DMS). The DMS will provide the connectivity between most telemetry sources and the onboard node for transmission to the ground. By far the bulk of data transported by DMS will be telemetry, however, not all telemetry will place the same demands on the communication system and DMS must also satisfy a rich array of services in support of distributed Space Station operations. These services include file transfer, data base access, application messaging and several others. The DMS communications architecture, which will follow the International Standards Organization (ISO) Reference Model, must support both the high throughput needed for telemetry transport, as well as the rich services needed for distributed computer systems. This paper discusses an architectural approach to satisfying the dual set of requirements and discusses several of the functionality vs. performance trade-offs that must be made in developing an optimized mechanism for handling telemetry data in the DMS.
    • Voyager Neptune Telemetry: The Voyager Telemetry System

      Madsen, Boyd D.; California Institute Technology (International Foundation for Telemetering, 1987-10)
      Improvements to the Voyager telemetry system, which have been implemented on the spacecraft and in the Deep Space Network (DSN), will allow a net science data return from Neptune essentially equivalent to that received from Saturn in spite of the increased range. Enhancements to the system performance include: Increased DSN ground station G/T, Inter-agency arraying, Spacecraft data compression, Reed-Solomon concatenated coding, Reduced telemetry link uncertainties. Net improvements totaled 8 dB in a system that was state-of-the-art when Voyager was launched in 1979.
    • The Voyager-2 Neptune Encounter

      Kosmann, William J.; The California Institute of Technology (International Foundation for Telemetering, 1987-10)
      Mankind's first in situ exploration of the planet Neptune and its moons, rings, and magnetosphere will occur during the summer of 1989. The Voyager system was designed to explore Jupiter and Saturn. However, Neptune is three times farther away than Saturn. The major science objectives and telecom link distance generate unique telecommunications requirements. Among these are conversion of the Deep Space Network's (DSN) 64 meter antennae to 70 meter antennae, arraying of the Very Large Array (VLA) with the DSN antennae at Goldstone CA, use of the 64 meter radio-telescope at Usuda, Japan, and new on-board spacecraft data control software. In addition, telecom improvements first made for the Uranus encounter, including parallel operation of the spacecrafts redundant data control processors, on-board spacecraft data compression software, and on-board data encoding hardware and software, will also be used for the Neptune encounter.
    • Telemetry Formats for the Space Station RF Links

      Marker, Walter; National Aeronautics and Space Administration (International Foundation for Telemetering, 1987-10)
      This paper discusses the formats that have been proposed for the manned Space Station space/ground RF link. In addition to discussing the specific RF formats, the paper seeks to discuss the requirements that have caused the proposed format to exist in its current form. The paper begins by briefly discussing the historical basis for telemetry formats within NASA, and then discusses the unique requirements that the Space Station imposes, compared to traditional space probes. The paper next treats the overall requirements that must be satisfied by the Space Station communications system. Finally the paper discusses the details of the RF format and its proposed operational usage.
    • Recent Trends in PSK Demodulation

      Roberts, R. H.; Tremain, George F.; Decom Systems, Inc. (International Foundation for Telemetering, 1987-10)
      Increased usage of PSK signals in TT&C formats has generated unique challenges for ground support equipment developers. DSI has met this challenge with the introduction of its model 7133 BPSK / QPSK modem. Enhanced on the Aerojet / USAF GS-14 program, the 7133 is the latest addition to the company's modem product line. The 7133 uses a dual mode cross arm Costas loop to demodulate BPSK or QPSK data. With an implementation loss averaging 0.8 dB, the 7133 demodulates asynchronous 2.56 MBps QPSK data. It also processes BPSK data at rates up to 2.56 MBps, with a loss of less than 0.5 dB. We present the 7133 demod design and test results. Current work at DSI extends the basic 7133 design to handle unbalanced QPSK formats. DSI's new model 7750 receiver-demodulator processes quadrature input signals either in pairs or independently. The 7750 uses phase locked loops to demodulate PSK, FM, PM or AM. We present the 7750 extended Costas loop design and preliminary test results. Finally, we look at applying recent DSP and NCO IC's to multi-mode TT&C demodulation.
    • Error Performance Bounds for M-Ary Digital FM with Predetection Sampling

      Cox, Timothy F.; Stanford University (International Foundation for Telemetering, 1987-10)
      Coherent detection of full response M-ary digital FM corrupted by additive white gaussian noise is studied. Prior to detection processing the signal plus noise is bandpass filtered and sampled. Upper error bounds which are applicable to the sampled system are given. With these bounds some comparisons of the effects of system parameter selection on the error performance can be made. These system parameters include deviation ratio, baseband pulse shape, sampling rate, number of levels (M), and signal-to-noise ratio.
    • The Instrumentation Data Recorder in an Automatic Mode to Record and Reproduce Digital Data

      Nottley, G. C.; THORN-EMI Technology (International Foundation for Telemetering, 1987-10)
      The conventional IRIG Instrumentation Tape Recorder has two major disadvantages when used to record and reproduce digital data. Firstly it has a limited number of discrete tape speeds, and secondly the operator has to calculate and then set the tape speed to give the appropriate packing density or clock rate. The use of microprocessors has made it possible to take the majority of these calculations, and also the setting up of the recorder, out of the users hands. Also the tape speeds available are virtually continuous over the range 17/8 ips to 120 ips. There are other facilities available and this paper describes the operation and facilities of an instrumentation recorder which is almost totally automatic.