• A Rate Distortion Surface for Images

      Jones, Richard A.; University of Arkansas (International Foundation for Telemetering, 1978-11)
      In this paper the concept of a rate distortion surface is introduced. A signal class is considered such that the source can be viewed as a composite source that consists of a finite number of subsources. Also, it is demonstrated that the overall transmission requirement can be treated as different but connected transmission requirements. The connection arises through an intermediate fidelity criterion. It is shown that the rate distortion bound for a composite source is a convex surface with a unique minimum for any specified signal to noise ratio. It is further demonstrated that the locus of these minima, projected onto a composite source information rate-composite source average distortion plane, is the rate distortion curve for the composite source.
    • Quantization for Signal Detection and Representation

      Kassam, Saleem A.; University of Pennsylvania (International Foundation for Telemetering, 1978-11)
      For digital representation of analog data the minimum mean-squared-error criterion is commonly used as a criterion for the basis of optimum quantizer design. In this paper we show that in some situations measures other than the minimum mean-squared-error may be more appropriate. For the signal representation problem, it is shown that the mean-absolute-error criterion has theoretical justification, as again for some signal detection problems it is shown that the mean-squared-error criterion is not the most appropriate criterion.
    • Millimeter Wave and Laser Satellite Communication System Comparison

      Goodwin, F. E.; Luke, R. T.; Hughes Aircraft Company (International Foundation for Telemetering, 1978-11)
      Satellite communications using laser technology has received support primarily due to its high data rate potentials. However, as laser technology progresses, the system advantages of reduced size and weight relative to millimeter wave systems are becoming more apparent and realizable. A detailed comparative study was undertaken to define the merits of both millimeter wave and laser technology for a satellite communication system operating at the relatively modest data rate of 100 megabits per second. The following paper defines the communication system parameters used in the study and summarizes the results obtained for the 100 Mbps system comparison.
    • Satellite Communication Simulation and Its Applications

      Wang, Lily L.; Yeh, Paul P.; The Aerospace Corporation (International Foundation for Telemetering, 1978-11)
      The computer simulation activities which have been carried out at The Aerospace Corporation for satellite link performance studies and system analysis are reported. A brief description of the modelings of a filter, nonlinear device, modulator, detector and receiver is also given. Some results from the simulation studies, such as the basic link performance in the presence of filters and nonlinear device (hard limiter or TWT), the comparisons of various modulation techniques (OK-QPSK, MSK and PFQPSK), the study of cross talk in a FDMA system, the interference or jamming at the presence of a nearby source, and finally, the intermodulation problem of a multiple channel MFSK system using the frequency hopping, are addressed.
    • Performance of Bandlimited and Hardlimited PSK Signals

      Rey, R. D.; TRW Defense and Space Systems Group (International Foundation for Telemetering, 1978-11)
      Transmission of a signal through a channel, such as a satellite communication channel, results in distortion of the signal due to bandlimiting in the individual channels and hardlimiting. The purpose of this paper is to study the effects that channel distortion due to filtering and hardlimiting have on the performance of BPSK and QPSK. The results will be used to determine the maximum bit rate which can be transmitted through a channel having a particular bandwidth with a specified limit in degradation of performance.
    • Detection of Moving Optical Objects

      Burczewski, R. M.; Mohanty, N. C.; Rockwell International (International Foundation for Telemetering, 1978-11)
      This paper deals with the detection of a moving optical object in the presence of background, sensor or star and other noise. The algorithms are derived to estimate noise statistics, and its extrapolation, signal statistics, and the criterion for detecting the moving objects. The performance of the algorithm has also been derived.
    • TDRSS Multiple Access Receiving Phased Array System

      DuPree, J. E.; TRW Defense and Space Systems Group (International Foundation for Telemetering, 1978-11)
      A 30-element phased array, with remote beamforming and multiple access signal design, is the basis for a new multiple access concept to be used by the Tracking and Data Relay Satellite System (TDRSS). System tradeoffs evolved a control and calibration concept which parallels modern estimation theory in dynamic systems and reduces the complexity of adaptive control while maintaining the necessary accuracy. A system dynamic model propagates "open loop" estimates of optimal weight vectors based on user satellite ephemerides derived from tracking data. A sampled-data closed loop adaptive control system periodically updates the beam-steering vector to eliminate parameter drifts and modeling errors, and to maintain the weight vector near optimum. The concept is primarily useful in the specified noninterference environment, though some nulling capability is possible.
    • Bubble Memories for Spacecraft Mass Storage Status and Potential

      Murray, Glenn W.; Rockwell International (International Foundation for Telemetering, 1978-11)
      A combination of solid state technology, high storage density and nonvolatility makes Bubble Memory Technology an attractive option for spacecraft system designers. It has the potential for not only replacing conventional spaceborne mass store media such as tape but also the flexibility to be configured into mass store system resembling disks providing the designer with memory organizations for space applications not previously available. The current state of this technology is assessed in terms of memory element, memory element packaging and system design with special attention to those aspects particularly relevant to space applications. Future developments in the technology and their impact on the capability and application are also considered.
    • A Comparison Between Coded MPSK and MFSK Systems

      Biederman, L.; Huang, T. C.; LinCom Corporation (International Foundation for Telemetering, 1978-11)
      The performance of two coded communication systems is compared. The first one is obtained when the system modulation is coherent PSK. The second system results when the modulation is noncoherent FSK. The coding parameter adopted to evaluate the system performance is the cut-off rate. A second parameter called coded throughput is derived from the cut-off rate and utilized to effectively compare the performance of the two coded systems under consideration.
    • GPS User Equipment, A Concept in Modular Design

      Candy, Donald W.; Hoover, Wayne M.; Texas Instrument Incorporated (International Foundation for Telemetering, 1978-11)
      A brief introduction to the Global Positioning System is presented. Functional modularity of GPS User Equipment systems and subsystems is studied. Physical modularity and commonality of hardware and software functions are discussed with respect to Design To Cost (DTC) and Life Cycle Cost (LCC) goals. Commonality of hardware and software support systems is explored with respect to increased development efficiency. Finally, a composite overview of the Texas Instruments High Dynamics and Manpack Vehicular User Equipments is presented with emphasis placed on the use of technology and vertical integration for DTC/LCC.
    • TDRSS Telecommunications MA Return Channel

      Weber, C.; Halderman, D.; Blyth, R.; University of Southern California; TRW, Defense & Space Systems Group (International Foundation for Telemetering, 1978-11)
      The Tracking and Data Relay Satellite System (TDRSS) relays signals to and from ground terminal and user satellites. No signal processing is done on the satellite and as many functions as possible have been removed from the satellite and implemented in the ground terminal. The multiple access (MA) users serviced by the S-Band thirty element phased array on the satellite require the capability to form up to twenty simultaneous tracking antenna beams by phase and amplitude weighting the individual antenna elements in the ground terminal. Frequency division multiplexing is used to transmit the 30 antenna elements to the ground for beamforming. Phase and amplitude uncertainties build up over time between the antenna elements and the beam processing on the ground. To optimize and maintain required performance, a calibration technique is required to estimate the channel weight correction table for the MA return link.
    • The Wide-Band Signal Processor

      Stiffler, J. J.; Raytheon Company (International Foundation for Telemetering, 1978-11)
      The Wide-Band Signal Processor (WBSP) is a spaceborne communications processor designed to operate as a peripheral to the Fault-Tolerant Spaceborne Computer (FTSC) currently being developed for the U. S. Air Force. Its function is to demodulate and decode received FDM and TDM signals and to re-encode the recovered information and use it to modulate signals for retransmission. The major difference between the WBSP and other processors designed to perform similar functions is in the fact that the WBSP, like the FTSC itself, is designed to survive its own hardware malfunctions.
    • Satellite, Surface, and Subsurface Optical Communications

      Mooradian, G. C.; Naval Ocean Systems Center (International Foundation for Telemetering, 1978-11)
      Optical communication in the atmosphere, space, the marine boundary layer, and underwater are being investigated for a variety of applications. Three classes of optical communications systems will be addressed: OCULT (Optical Communications Using Laser Transceivers), ELOS (Extended Line-of-Sight) optical communications and satellite to subsurface optical communications. OCULT is a 10.6μ high rate reciprocal tracking heterodyne laser communications system designed for nearly all-weather duplex video bandwidth communications to horizon limited ranges. Of special interest are effects of coherent propagation through fogs and turbulence. The ELOS system is a 1.06μ optical aerosol scatter communications system for ranges of 30 to 300 miles. Scattering measurement at 40 to 80 miles through the marine boundary layer will be presented. The satellite to subsurface communication efforts deal with blue/green transmission from a satellite, through the atmosphere (including clouds) to a submerged receiver, exploiting the blue/green "window" in ocean water. The multiple forward scattered and diffusion transport of serm-plane waves through clouds and ocean waters will be discussed.
    • A Transition Density Analyzer for High Density Digital Codes

      Petit, R. D.; Odetics Incorporated (International Foundation for Telemetering, 1978-11)
      A portable test instrument useful in optimizing the performance of high density digital recorders is described in this paper. The instrument, a transition density analyzer, provides a graphic display of the distribution of transitions with respect to time for a variety of PCM digital data formats. The concept of a transition density analyzer as an improvement upon eye pattern assessment techniques was presented at the 1976 International Telemetering Conference by Mr. J. P. Lerma of Odetics, Inc., Anaheim, California. Mr. Lerma's paper emphasized the mathematical modeling of probability density functions and the synthesis of these models by a density analyzer. Mr. Lerma's concept has since been reduced to a working prototype which is currently under evaluation at Odetics. Discussed in this paper are the operational characteristics of the instrument as well as applications and the results of its usage on some high density digital recorders.
    • Solid State Microwave Power Amplifiers - An Overview

      Lewinter, S. W.; The Aerospace Corporation (International Foundation for Telemetering, 1978-11)
      This paper summarizes results that have been achieved with various types of microwave solid state power amplifying devices and presents some projections of advances that can be expected within approximately a five year period. The frequency band surveyed extends from 1 to 100 GHz. The emphasis is on CW or high duty cycle pulse applications, where long life is of great importance, such as in a satellite communication system. The types of devices considered include the gallium arsenide field-effect transistor (GaAs FET), IMPATT diodes, bipolar transistors, Gunn diodes, TRAPATT diodes and electron bombarded semiconductor (EBS) devices. An overview of the technology of microwave power combiners is also included.
    • End-To-End Information System Design at the NASA Jet Propulsion Laboratory

      Hooke, Adrian J.; NASA Jet Propulsion Laboratory (International Foundation for Telemetering, 1978-11)
      Recognizing a pressing need of the 1980's to optimize the two-way flow of information between a ground-based user and a remote space-based sensor, an end-to-end approach to the design of information systems has been adopted at the Jet Propulsion Laboratory. The objectives of this effort are to ensure that all flight projects adequately cope with information flow problems at an early stage of system design, and that cost-effective, multimission capabilities are developed when capital investments are made in supporting elements. This paper reviews the End-to-End Information System (EEIS) activity at the Laboratory, and notes the ties to the NASA End-to-End Data System program.
    • Status Report on TDRSS

      Holmes, W. Morris, Jr.; TRW Inc. (International Foundation for Telemetering, 1978-11)
      The NASA Satellite Tracking and Data Network (STDN) will be replaced by the Tracking and Data Relay Satellite System (TDRSS) during the 19801's. The coverage available to user satellites will be increased dramatically and very high data rates will be provided. Real-time data analysis and adaptive satellite control will be possible with the availability of continuous two-way communications. TDRSS will provide these benefits while lowering the cost of tracking and communicating with NASA satellites. Communication requirements will be different for satellite designers in the 1980 period. TDRSS user satellites will require higher transmitter power and more sensitive receivers, and will communicate using special TDRSS modulation formats. There will be less onboard data storage. This paper provides an overview of the TDRSS as it is being built. The major system features are described, and some of the system characteristics that will affect user satellite mission planning are considered.
    • A Distributed Shortest - Path Algorithm

      Humblet, Pierre A.; Massachusetts Institute of Technology (International Foundation for Telemetering, 1978-11)
      The problem of routing in a data network is often treated by assigning traffic dependent lengths to the links of the network and routing traffic from node i to node j along the shortest path from i to j . We present a distributed algorithm in which the nodes cooperate to find all shortest paths. It runs asynchronously in every node and does not require the network topology, or even the number of nodes in the network, to be known a priori by the nodes.
    • Space Shuttle Orbiter Processing, Monitoring, and Telemetry Systems

      Carrier, Louis M.; Robitaille, Richard A.; Rockwell International (International Foundation for Telemetering, 1978-11)
      The transportation vehicle for launching personnel and payloads into earth orbit during the 1980's and subsequent years will be NASA's space shuttle. The space shuttle flight system consists of an orbiter, an external tank, and two solid rocket boosters. The orbiter, a key element of the Space Shuttle, is launched into space like a conventional launch vehicle, performs on-orbit payload missions, enters the atmosphere, and lands much like a conventional commercial jet aircraft. This paper provides an overview of the Space Shuttle avionics with prime emphasis on how the orbiter's on-board processing, monitoring, and telemetry systems function during the on-orbit mission phase. Included is a description of the S-band and Ku-band RF transmission link and its relationship to the ground systems, payload interfaces, and support equipment. Also discussed are the flexibility of its instrumentation system (including capability to provide formats), features of the on-board monitoring systems (dedicated displays, cathode-ray tubes, and caution and warning systems), and methods for storing and processing data (recorders, mass memory, and on-board computers). The orbiter's avionic services to the payloads and the future growth of the Space Transportation System and the orbiter are also discussed briefly.
    • The NASA Standard Telemetry and Command Components (STACC)

      Eliott, Noel P.; Gonyea, Richard; Nostrand, Barbara; Orlowski, Ike; Valentine, William; Spacetac (International Foundation for Telemetering, 1978-11)
      The Standard Telemetry and Command Components (STACC) were conceived by NASA for use on the Multimission Modular Spacecraft. The components have wider application, however, and already are being considered for many other spacecraft. A programmable Central Unit controls Remote Interface Units via a full duplex data bus, providing data acquisition and command distribution capability throughout the spacecraft. The Central Unit can meet any uplink, time code, and format requirements without hardware changes. Each remote unit can acquire any type of data (serial digital, bi-level, analog, or passive analog) on any channel. A third type of unit is an optional interface providing I/O capability to an on-board computer. The protocols used on the 1Mbps data bus are compatible with MSFC's "Standard Interfaces for Digital Data, Multiplex Serial Data Acquisition and Distribution Systems (SIDD/MSDADS Standard)". The bus design saves significant harness weight and simplifies the single point ground and isolation approaches.