• 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.
    • Phase Tracking Error in a Fading Channel

      Mohanty, Nirode; The Aerospace Corporation (International Foundation for Telemetering, 1987-10)
      The phase tracking error of the reception of a QPSK signal transmitted in a severe fading environment is derived. The phase estimate derived from the phase lock loop (PLL) will be used by a binary phase shift keying (BPSK) receiver for the recovery of the data. The resultant probability of bit error is analyzed, and is shoen to be significantly improved when the phase of the transmitted signal is tracked by a PLL separately and utilized in the coherent detection.
    • 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.
    • 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.
    • 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.
    • 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.
    • TDRS Ku-Band Gateway

      Collins, Cynthia M.; Lecha, Javier; Principe, Caleb M.; Ross, Douglas; Goddard Space Flight Center (International Foundation for Telemetering, 1987-10)
      The Wideband Transport Frame Formatter (WTFF) is the Tracking and Data Relay Satellite (TDRS) Ku-band return link gateway. This gateway is designed to support the Consultative Committee for Space Data Systems (CCSDS). The WTFF is being developed by Goddard Space Flight Center as a proof of concept project for the CCSDS and the National Aeronautics and Space Administration (NASA). This design is in many aspects consistent with the Open System Interconnect (ISO) model's "lower layer architecture". The WTFF system is a multiplexing device developed to process and downlink the high rate data generated by a wide variety of users. The WTFF is designed to frame and format high data rate user channels into transport frames and multiplex according to a predefined schedule into two bit streams that are compatible with TDRS Ku I and Q band service. The combined data rate will be 300 Mbps. The WTFF will service up to eight input channels generating data in the range of 10 to 150 Mbps. In addition to these input channels, audio data will be accepted by the WTFF system and inserted in the downlink. A second function of the WTFF is to provide telecommunication coding as assigned to each virtual channel to ensure a given quality of service.
    • 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.
    • 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.
    • 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.
    • 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 4 Mbps Digitizer with 100 kHz Signal Bandwidth

      Enterkine, Robert; Naval Weapons Center (International Foundation for Telemetering, 1987-10)
      This paper presents a non-standard digitization scheme which samples the data asymmetrically in order to maximize data bandwidth. Two frame sychronization words are utilized in a separated manner to permit their replacement with the average value of adjacent data words during the decommutation process.
    • 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.
    • Advanced Joint Test Assembly (JTA) Telemetry System

      Stimmell, K. G.; Sandia National Laboratory (International Foundation for Telemetering, 1987-10)
      We design telemetry systems which instrument weapons in the Joint DoD/DOE flight test program. These telemetry systems gather data which can be used to determine if a weapon functioned as intended. Traditionally, a telemetry system has been designed to fit the individual requirements of each of the many weapons which have gone into production. The process of defining requirements, designing the system, and getting it into production with the quality assurance demanded of all weapon components takes considerable time, manpower, and money. Due to the rapid advancement of electronics and computer technology, these telemetry systems and their production testers become difficult to support if the weapon service time is extended or if aging test equipment breaks down. We are designing a telemetry system to support new programs for the next decade and to replace old telemetry systems which can no longer be produced. This multi-system Joint Test Assembly (JTA) is being designed to be modular, flexible, and testable. New techniques for increasing reliability, such as redundancy, error detection and correction, and microprocessor recovery will be employed. The requirements for each program can be met by choosing the necessary circuitry from a "shopping list" and packaging to meet the mechanical constraints for each system. Production specifications and test equipment will be in place to support any telemetry which is composed of the previously-designed modules. Modifications of hardware and software to support individual requirements will be kept to a minimum. We expect this new approach to telemetry system development to significantly reduce cost and lead time for every program on which it is employed. The use of this telemetry system on multiple programs should also enhance reliability.
    • Parallel Distributed Processing of Realtime Telemetry Data

      Murphy, Donald P.; Syndetix, Inc. (International Foundation for Telemetering, 1987-10)
      An architecture is described for Processing Multiple digital PCM telemetry streams. This architecture is implemented using a collection of Motorola mono-board microprocessor units (MPUs) in a single chassis called an Intermediate Processing Unit (IPU). Multiple IPUs can be integrated using a common input data bus. Each IPU is capable of processing a single PCM digital telemetry stream. Processing, in this context, includes conversion of raw sample count data to engineering units; computation of derived quantities from measurement sample data; calculation of minimum, maximum, average and cyclic [(maximum - minimum)/2] values for both measurement and derived data over a preselected time interval; out-of-limit, dropout and wildpoint detection; strip chart recording of selected data; transmission of both measurement and derived data to a high-speed, large-capacity disk storage subsystem; and transmission of compressed data to the host computer for realtime processing and display. All processing is done in realtime with at most two PCM major frames time latency.
    • 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.
    • 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.
    • 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.
    • 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.