• 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.
    • Trends in Space Shuttle Telemetry Applications

      Muratore, John F.; Lyndon B. Johnson Space Center (International Foundation for Telemetering, 1987-10)
      During early manned spacecraft operations, the primary role of ground telemetry systems was data display to flight controllers. As manned spaceflights have increased in complexity, greater demands have been placed on flight controllers to simultaneously monitor systems and replan systems operations. This has led to interest in automated telemetry monitoring systems to decrease the workload on flight controllers. The Mission Operations Directorate at the Lyndon B. Johnson Space Center has developed a five layer model to integrate various monitoring and analysis technologies such as digital filtering, fault detection algorithms, and expert systems. The paper describes the five layer model and explains how it has been used to guide prototyping efforts at Mission Control. Results from some initial expert systems are presented. The paper also describes the integrated prototype currently under development which implements a real time expert system to assist flight controllers in the Mission Control Center in monitoring Space Shuttle communications systems.
    • 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.
    • The Real-Time Telemetry Processing System III

      Shelley, Larry R.; Computer Sciences Corporation (International Foundation for Telemetering, 1987-10)
      The Navy's Real-time Telemetry Processing System (RTPS III) is a third generation system. Designed and built by Computer Sciences Corporation (CSC), RTPS III will support the demands of the Navy flight test community well into the 1990's. The RTPS III is custom-crafted using CSC's system development methodology which blends the best features of the current Navy RTPS system and previously proven CSC systems. A major objective of CSC's RTPS III design is the continuation of existing Navy user interfaces. The transition from the existing system to the integrated RTPS III has also been facilitated by the incorporation of common interfaces to Navy applications software, thus ensuring "new system" acceptance. RTPS III is designed to include a powerful front-end capable of Engineering Unit conversions at more than 200,000 samples per second (sps) per telemetry stream with expansion to 500,000 sps. It will include networking concepts which allow the simple addition of additional subsystems should expansion be required. RTPS III also supports both secure and integrated modes of operation for classified and unclassified processing. The CSC design, a custom combination of proven and new development, results in a Navy system which meets tomorrow's flight test requirements today. Other benefits to NATC are a modular, cost-effective solution with lower life-cycle costs, and a broader range of possibilities for evolving and reconfiguring the system to service new applications and users.
    • International Telemetering Conference Proceedings, Volume 23 (1987)

      International Foundation for Telemetering, 1987-10
    • 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.
    • 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.
    • Data Relay System for Space Shuttle and Payload Pre-Launch Checkout

      O'Donnell, Hugh B.; Wise, Thomas E.; Ngo, David Q.; GSFC; BFEC (International Foundation for Telemetering, 1987-10)
      Engineering requirements and design characteristics of the coherent throughput relay system which supports East Coast pre-launch checkout of NASA's Space Shuttle and its Payloads are presented. The Relay system is required to provide communications through NASA's Tracking and Data Relay Satellite System for the Shuttle and Payload-Users while they are encapsulated in the launch preparation facilities at the John F. Kennedy Space Center and the Eastern Test Range, Florida. The Relay system is required to be transparent to its users' data at all rates up to three MB/s at S-band and 300 MB/s at Ku-band. Noise and group-delay distortion are major contributors to wide band RF signal degradation. These were major factors in the Relay system design. Antenna design, pointing angle and location were constrained by the need to maximize end-to-end RF signal isolation at both S-band and KU-band, simultaneous forward and return frequencies. System characteristics and link analysis are also presented. In addition, a similar Data Relay located at Vandenberg Air Force Base is briefly described.
    • An Inexpensive S-Band Angle Pointing Technique for Steering a Narrow Beam Ku-Band Antenna

      Line, Larry; Hager, Fred; Hanson, Duke; Kral, Kevin; Moss, Robert; Goddard Space Flight Center; Motorola, Inc.; Honeywell-Speery Space Systems; Westinghouse Electric Corporation (International Foundation for Telemetering, 1987-10)
      A recently tested antenna pointing control system for gimbaled antennas has been developed. A modified TDRSS user transponder produces pointing error signals from the S-band forward link which in turn drive the Steering Control Electronics (SCE) to precision steer a S-/Ku-band Data and S-band Tracking (KDST) planar array. A successful test of the pointing and data handling capabilities is described and plans for further tests, incorporating additional refinements, are presented.
    • Differential Sampling for Fast Frequency Acquisition Via Adaptive Extended Least Squares Algorithm

      Kumar, Rajendra; California Institute of Technology; California State University (International Foundation for Telemetering, 1987-10)
      This paper presents a differential signal model along with appropriate sampling techniques for least squares estimation of the frequency and frequency derivatives and possibly the phase and amplitude of a sinusoid received in the presence of noise. The proposed algorithm is recursive in measurements and thus the computational requirement increases only linearly with the number of measurements. The dimension of the state vector in the proposed algorithm does not depend upon the number of measurements and is quite small, typically around four. This is an advantage when compared to previous algorithms wherein the dimension of the state vector increases monotonically with the product of the frequency uncertainty and the observation period. Such a computational simplification may possibly result in some loss of optimality. However, by applying the sampling techniques of the paper such a possible loss in optimality can be made small.
    • VLA X-Band Preparation for Voyager 2 at Neptune

      Brundage, William D.; National Radio Astronomy Observatory (International Foundation for Telemetering, 1987-10)
      The Very Large Array (VLA) radio telescope, located in west-central New Mexico, obtains high-resolution radio images of astronomical objects by using Fourier aperture synthesis with 27 antennas. With the addition of X-band to its receiving capabilities by 1989, and when arrayed with the Goldstone Deep Space Communications Complex (GDSCC), the VLA will double the Deep Space Network (DSN) receiving aperture in the U. S. longitude for signals from Voyager 2 at Neptune. This paper describes the VLA and the installation of the X-band system, its operation and performance for Voyager data reception, and its capabilities for other science at X-band.
    • 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.
    • 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.
    • 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.
    • 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.
    • A Distributed Systems Approach to Real-Time Data Acquisition and Monitoring

      Fidell, Sanford; Fortmann, Thomas; Moss, Peter; BBN Laboratories, Inc. (International Foundation for Telemetering, 1987-10)
    • Spectrum Utilization for the International Space Station Communications and Tracking Systems

      Novosad, Sidney W.; Johnson Space Center (International Foundation for Telemetering, 1987-10)
      Over its lifetime, the international Space Station Program will use a variety of communications and tracking systems which could span the frequency spectrum from VHF to optical wavelengths. Primary communications traffic will initially occur in the S-band and Ku-band regions. Tracking will initially consist mostly of L-band satellite links. As the demand for more C&T services increases in the growth phase, use of millimeter and optical wavelengths will be required. Although many issues remain to be resolved, the most significant interference concern at present is that of Ku-band space/space links between co-orbiting Space Station elements.
    • 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.
    • 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.
    • An Asynchronous Digital Interface for SLAT Telemetry

      Drescher, Leo; Martin Mariette Orlando Aerospace (International Foundation for Telemetering, 1987-10)
      This paper describes telemetry used in the Supersonic Low Altitude Target (SLAT) built for the U.S. Navy by Martin Marietta. Feeding digital inputs directly to a pulse code modulation (PCM) encoder, bypassing the analog-to-digital (A/D) converter, and injecting into the output PCM wavetrain is well known. Various techniques for accomplishing this have been reported; however, they all have time correlation and synchronization problems. The system to be described involves asynchronous data transfer from the digital computer to the PCM encoder. The system uses a dual-port random-access memory (RAM) to effectively decouple the computer output, which is running synchronously on its 6 MHz clock, from the PCM wavetrain, which is running at 128 kilobits per second. Data from the computer is being "written into" the RAM simultaneously while data is being "read out." Contention arbitration prevents loss of data when read and write ports of the same address are activated. A "forbidden code" provides a special code when the computer is not connected or is producing all zeros.