• 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.
    • 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.
    • D-1 and DCRSi: The Present and the Future

      Wood, Tracy G.; Ampex Corporation (International Foundation for Telemetering, 1987-10)
    • The Generic Data Capture Facility

      Connell, Edward B.; Barnes, William P.; Stallings, William H.; Goddard Space Flight Center (International Foundation for Telemetering, 1987-10)
      The growing complexity of space science missions is causing a dramatic increase in the data rates and volumes from spaced-based experiments, and the ground operations functions associated with handling data from these missions are growing in complexity consistent with this increase. A key requirement on the systems that provide data handling support is to control operations costs carefully while providing high-quality data capture functions. One approach to meeting this particular objective that has been taken at the Goddard Space Flight Center has been to initiate the development of a Generic Data Capture Facility (GDCF) that can provide data capture support for a variety of different types of spacecraft. The GDCF is emerging through a blend of new system development and evolution of existing systems, and when complete, it will have the capability to support the two major data formatting schemes (packet and Time-Division Multiplexed (TDM)). The specific implementations are designed to support the Gamma Ray Observatory and the Upper Atmosphere Research Satellite, but the GDCF will provide the baseline system to support various new missions as they emerge.
    • Binary Decision Machines: Alternative Logic for Telemetry Control

      Croson, E.; Howard, J.; Jue, L.; University of California, Santa Barbara (International Foundation for Telemetering, 1987-10)
      A Binary Decision Machine (BDM) is described as a means of achieving logical control of data acquisition equipment and telemetry systems. The basic architecture of a BDM is initially presented followed by a description of its implementation as a Very Large Scale Integration (VLSI) device. Performance characteristics, programming, and ease of use as a controller are then presented via actual applications. The results of these endeavors led to a means of digitizing and extracting doppler data in a missile telemetry system.
    • 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.
    • 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.
    • 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.
    • 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.
    • International Telemetering Conference Proceedings, Volume 23 (1987)

      International Foundation for Telemetering, 1987-10
    • 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.
    • 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.
    • 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.
    • 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 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.
    • 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.
    • 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.
    • 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.