• International Telemetering Conference Proceedings, Volume 20 (1984)

      International Foundation for Telemetering, 1984-10
    • AN OVERVIEW OF THE GPS DEMONSTRATION PROGRAM FOR RANGE APPLICATIONS

      Knoernschild, Gene F.; Rockwell International (International Foundation for Telemetering, 1984-10)
      This paper describes a program to evaluate the use of an integrated GPS/INS system as the source of Time/Space/Position for participant tracking in range applications.
    • A COMPUTERIZED CHECK-OUT SYSTEM FOR TRANSDUCERS IN NUCLEAR POWER PLANTS

      Brandt, Axel; SCS Technische Automation und Systeme GmbH (International Foundation for Telemetering, 1984-10)
      A computerized check-out system for recording and analysis of test data of transducers in nuclear power plants is described. The system is composed of two subsystems, the STATIONARY and the MOBILE SYSTEM. The STATIONARY SYSTEM fulfills all necessary administrative functions, allows data analysis, reporting, and longterm storage of test data. The MOBILE SYSTEM is the test device. It is set up by three components - controller unit, interface, and microcomputer - the whole being assembled on a moveable wagon which makes on site testing of the transducers possible. The number of MOBILE SYSTEMS is selectable according to user needs and environmental condititions. Data transport between the systems is accomplished via magnetic tape cartridges or online by a standardized communication line.
    • The Role of Telemetry In Navstar Checkout

      Radak, J. Jr.; Mercadante, D. S. (International Foundation for Telemetering, 1984-10)
      Numerous checkout systems are being conceived for factory test, launch readiness assessment, and on-orbit performance evaluation for spacecraft designs of ever-increasing complexity. These systems must in addition be extremely flexible in design to maintain supportive capability at reasonable cost during transition from development through operational program phases. This paper describes a telemetry dependent checkout system for the Navstar Global Positioning Satellite. The Space-Ground Link System (SGLS) compatible telemetry based checkout features elemental units that simulate the Satellite Test Center (STC) and the Remote Tracking Stations (RTS). This approach minimizes the duplication of hardware and software design and documentation for the overall spacecraft assembly-to-orbit checkout process. The telemetry-checkout design is shown to be versatile enough to support growth in both numbers and types of payloads; to reduce the operator training demands; to provide test results, equipment status, and other data to remote evaluation personnel; and to improve delivery through computer-assisted performance assessments.
    • Remote Control of an Impact Demonstration Vehicle

      Craft, James B., Jr.; Harney, Paul F.; Johnson, Richard G.; NASA Ames Research Center; Dryden Flight Research Facility (International Foundation for Telemetering, 1984-10)
      The Full Scale Controlled Impact Demonstration (CID) program is a joint NASA/FAA effort to test improvements in aircraft crashworthiness. Specifically, a transport aircraft was modified to be remotely piloted by telemetry control and flown into a “survivable” crash. On board was a fuel cargo of anti-misting kerosene (AMK) to inhibit post crash fires. Also, various measurements were made to examine crash structural response, and improvements in new seat and restraint design using instrumented anthropomorphic dummies. Mechanization of the remote uplink telemetry command system and the downlink data systems is described.
    • FIELD TEST ACCURACY RESULTS OF THE DIFFERENTIAL NAVIGATION TECHNIQUE WITH NAVSTAR/GLOBAL POSITIONING SYSTEM

      Fickas, Ernest T.; Wadsworth, Isobel M.; SRI International (International Foundation for Telemetering, 1984-10)
      The Global Positioning (GPS), which is being developed by the DoD to support the operational forces, is a navigation aid that provides the user with precise position, velocity, and time information anywhere within line-of-sight of four satellite transmitters. It also holds potential benefits for use by the civilian community and the DoD test and training ranges. The differential navigation technique consists of using measurements from reference user equipment at a precisely known location to provide correction data to improve the navigation solution of a user equipment at an unknown location. The correction data consist of errors in position estimates derived from reference receiver output using the known true location coordinates. These data are applied to the output of the user equipment (at the unknown location) to remove common-mode errors due mainly to ionospheric propagation delays and satellite clock and ephemeris errors. Data were collected for user-to-reference separation distances of from zero to 280 nmi at night. Accuracies achieved do not confirm predictions of a degradation in efficacy of differential corrections with increasing separation distance; however, local disturbances at either GPS receiver cause considerable dispersion in the data.
    • A Programmable Data Acquisition System with Integrated Test and Calibration Facilities

      Zach, Adolf; Gandert, Rüdiger; Deutsche Forschungs- und Versuchsanstalt für Luft- und Raumfahrt e.V. (DFVLR) (International Foundation for Telemetering, 1984-10)
      In 1985 the new Advanced Technologies Testing Aircraft System (ATTAS) will be operable at DFVLR Braunschweig. For this research aircraft a flexible, highly accurate and testable data acquisition system was developed. It consists of a modular and distributed microprocessor system with signal conditioning units situated near the sensors. It is controlled by a master unit with an integrated PCM encoder. The flexible signal conditioning featuring software-controlled parameters and adaptable signal inputs, can be tested automatically via the analog calibration bus using switchable signal paths. The system will be presented in detail and its performance will be shown by typical examples of application within ATTAS.
    • BENEFITS OF USING A PROGRAMMABLE ARCHITECTURE MULTIPROCESSOR IN A REAL TIME TELEMETRY SYSTEM

      Lewis, Malcolm L; ACROAMATICS, Inc. (International Foundation for Telemetering, 1984-10)
      Designing and constructing a real time telemetry system for unique applications can involve considerable time to evaluate, choose, acquire, and interface the necessary elements. The use of a highly versatile single chassis telemetry acquisition system can reduce or obviate the need for external pre- or post-processors as well as the potentially difficult hardware and software interfacing. It also results in an easily upgradable and generally modifiable system from the development phase, through delivery, and on site by both the designer and user. The basis of the system described here is a parallel/serial multiprocessor whose architecture is programmable.
    • HIGH DYNAMIC GPS UNAIDED PSEUDORANGE TRACKING DEMONSTRATION

      Hurd, William J.; Statman, Joseph I.; Jet Propulsion Laboratory, California Institute of Technology (International Foundation for Telemetering, 1984-10)
      A breadboard high dynamic GPS receiver capable of pseudorange tracking with accelerations of 50 g or higher without inertial aiding is presented. The receiver uses cross correlation followed by fast Fourier transformation to approximate maximum likelihood estimation of pseudorange and range rate, with no phase or delay locked loops. The breadboard system consists of a one channel receiver and a high dynamics signal simulator. A planned demonstration of the receiver is described and anticipated results are presented showing pseudorange lag errors of under 10 m with acceleration of 50 g.
    • TECHNICAL CONSIDERATIONS FOR SURVIVABLE/MOBILE SPACE SUPPORT SYSTEMS

      Winslow, Roger G.; Winslow Consultants (International Foundation for Telemetering, 1984-10)
      The increased United States dependency on space systems for military operations has resulted in the need for major upgrades in the survivability of our space systems in both the space and ground segments. Achievement of this survivability upgrade is in turn dependent on the exploitation of new technologies across a broad spectrum of disciplines. This paper will focus on the technologies which must be considered for enhancing the survivability of the space mission ground segment. Technologies to be discussed will include nuclear hardened mobile terminals, rapidly deployable multiple frequency antennas, ranging from S-Band to EHF, A-J communications, standardization, application of VHSIC and VLSIC, Artificial Intelligence, simulation and built-in test.
    • MODULAR SURVIVABLE SATELLITE SUPPORT

      Wagner, Robert E.; Ford Aerospace & Communications Corporation (International Foundation for Telemetering, 1984-10)
      National defense strategies rely on force enhancement, space defense, space control and space force application functions being provided by survivable space resources. The ground command and control support for these functions must be at least equally survivable. An approach to meeting these ground survivability requirements is presented in this paper. A highly mobile satellite control system is presented incorporating recent technology advances into a modular design that satisfies a wide variety of user requirements in all levels of conflict. Ground/Air Transportability is enhanced significantly by the incorporation of monolithic phased arrays and miniaturized Tracking, telemetry and command (TT&C) equipment and data processing hardware. Hardness is enhanced by the incorporation of new materials and an advanced structural design that protects against EMP, blast thermal effects and terrorist activities. A preliminary design is described that indicates how modularity supports a spectrum of expected operating scenarios.
    • THE USE OF TRANSLATORS WITH GPS

      Johns Hopkins University; Westerfield, Edwin E. (International Foundation for Telemetering, 1984-10)
      A method for determining position and velocity as a function of time is required in order to test many systems involving moving platforms, such as missiles or sonobuoys. The Air Force Global Positioning System (GPS) is ideally suited for providing this information. Limitations exist, however, in currently available receivers. They are expensive to use in expendable platforms, plus they require more volume and power than are typically available. An alternative is to use either a translator or a transdigitizer in the vehicle under test. The signals transmitted by the GPS satellites are received by antennas on the missile, translated to a frequency in the telemetry band, amplified, and transmitted to a receiving station. In addition, if a transdigitizer is used, the signal is digitized prior to transmission. Specially designed receiving equipment on the ground processes the transmissions from the translator/transdigitizer, tracks the transmissions from each satellite, and makes the measurements necessary to allow the computation of the platform position and velocity. These systems concepts will be discussed, and a system currently using a translator in a missile and a system using a transdigitizer in a sonobuoy will be described in detail.
    • SATELLITE ACQUISITION USING AN AUTOMATED TECHNIQUE

      Reinhard, Kenneth L.; Darlington, John C.; Ford Aerospace & Communications Corporation (International Foundation for Telemetering, 1984-10)
      Automated acquisition of a satellite’s downlink signal by the main beam of a ground station’s tracking antenna is complicated by the presence of antenna pattern sidelobes and potential large uncertainties in the spatial and/or frequency location of the signal. Sidelobe acquisition prevents autotracking and telemetry reception, and large uncertainties require time for coordinated antenna and receiver search. Use of an auxiliary antenna assists in resolving the sidelobe intercept problem, and a high speed digital receiver alleviates the problems associated with spatial and frequency uncertainty. The antenna and receiver, under processor control, constitute a fully automated system. The associated processor software controls the antenna motion during the search phase, selects the proper receiver configuration for the expected signal environment, makes the main beam versus sidelobe intercept decision and switches to autotrack mode upon successful signal acquisition.
    • SURVIVABLE C³ FOR THE FUTURE

      Pasek, G. E.; Lockheed Missiles and Space Corporation (International Foundation for Telemetering, 1984-10)
      The paper will summarize the approach and considerations being given to the development of a survivable Mission Control Segment. Satellites of the future need to be designed with control needs in mind and provided with a high degree of autonomy and intelligence. Earth based support must be designed around operators who are limited in skill and therefore rely on sophisticated software and a degree of Artificial Intelligence. The total system approach, progress, and findings for these future Space and Ground Systems will be presented during the 20+ minute overview discussion.
    • SPACE LASER COMMUNICATIONS COMPETITION FOR MICROWAVES

      Svorec, Raymond W.; Gerardi, Francis R.; The Aerospace Corporation (International Foundation for Telemetering, 1984-10)
    • TRACKING AND DATA RELAY SATELLITE SYSTEM (TDRSS) SYSTEM OVERVIEW AND REIMBURSABLE USE

      Scott, James N.; Goddard Space Flight Center, National Aeronautics and Space Administration (International Foundation for Telemetering, 1984-10)
      The first satellite (TDRS-1) of the three-satellite TDRSS was launched by NASA in April 1983. A booster failure resulted in a delay in achieving the final synchronous orbiting position (until the following October) and has caused a delay in the launching of the second and third satellites. Nevertheless, NASA has obtained considerable operational experience with TDRS-1 and is generally pleased with the performance to date. This paper will provide an overview of how the TDRSS operates and its status, and will provide information about the policy, costs, and procedures regarding use of the system by non- NASA organizations.
    • SINGLE EVENT UPSETS IN SPACECRAFT DIGITAL SYSTEMS

      Lewkowicz, Paul E.; Richter, Linda Jean; Hughes Aircraft Company (International Foundation for Telemetering, 1984-10)
      This paper describes the physical environment that can result in random bit changes in space-borne memory systems. The impact of bit flips in digital telemetry systems is emphasized, with special attention paid to software requirements for protection from single event upset (SEU) effects. Some observations on incidence rates are presented along with an outline of hardware and software methods that can be taken to prevent future SEU problems. Several conclusions are drawn about strategies for preventing data corruption on the next generation of satellites in the presence of SEU-inducing particles.
    • A BROADBAND DIGITAL GEOPHYSICAL TELEMETRY SYSTEM

      Seeley, Robert L.; Daniels, Jeffrey J.; U.S. Geological Survey (International Foundation for Telemetering, 1984-10)
      A system has been developed to simultaneously sample and transmit digital data from five remote geophysical data receiver stations to a control station that processes, displays, and stores the data. A microprocessor in each remote station receives commands from the control station over a single telemetry channel. The commands adjust the sensing amplifier’s input voltage range (1 microvolt to 2 volts peak-to-peak), the number of samples (128 to 30,000), the sampling rate (256 to 32,768 samples/sec), and the number of signals (1 to 16) to average at the remote stations. A 12 bit analog-to-digital converter samples data with bandwidths of 100 Hz to 10 kHz for time periods selected from 100 seconds to 1 second, respectively. Each remote station begins sampling geophysical signals when it receives a synchronizing pulse relayed from the control station. Digitized geophysical data is transmitted to the control station over broadband (100 kHz bandwidth) UHF telemetry channels using standard asynchronous serial (19.2 kbaud) techniques and hardware dropout detection and recovery. The amount of data (480 kbits) and the maximum time to transmit data (30 secs) dictate using broadband telemetry (even though most geophysical telemetry is less than 10kHz in bandwidth). Header information (transmitted before the data) contains station number, digital sampling parameters, transmission block size, and checksum. This information is used by a computer program (in a PDP-11/23 (***) minicomputer) to maintain up to 5 simultaneous Direct Memory Access (DMA) transfers from the remote stations into 5 separate data buffers. Filled buffers are transfered (via an IEEE-488 bus) to an interactive analysis and display system (HP9845C (***)) for selecting data to be stored on magnetic media for subsequent laboratory analysis.
    • APPLYING TELEMETRY THEORY TO THE REAL-WORLD

      LAW, EUGENE L.; Pacific Missile Test Center (International Foundation for Telemetering, 1984-10)
    • ANALYTICAL STUDY ON BIT-SYNCHRONIZATION PROBLEMS IN A CODED COMMUNICATION SYSTEM

      Ng, Wai-Hung; The Aerospace Corporation (International Foundation for Telemetering, 1984-10)
      Many bit-synchronization techniques in digital communications depend on bit transitions for successful operation. In this paper, we first categorize the four main sources of generating transitionless signals. Then we describe general properties of channel coding and explain that, by injecting a well-selected detectable error pattern into the transmitted and coded signal, this bit transitionless problem can be eliminated without any additional bandwidth penalty. Finally, examples in both block code and convolutional code are selected for illustrating this simple but useful application.