• HIGH RESOLUTION DIGITAL DATA TRANSITION ANALYSIS AND TESTING

      Petit, Richard D.; Kode Inc., a Subsidiary of Odetics Inc. (International Foundation for Telemetering, 1983-10)
      The need for margin analysis in high density digital data storage systems is established. A review of margin analysis techniques is presented. This review includes a discussion of time interval analysis and a series of instruments which have evolved as a means of performing this analysis. Emphasis is given to a high resolution (1 nanosecond) statistically oriented embodiment of such an instrument.
    • GALILEO PROBE RELAY RECEIVER: ACQUISITION AND TRACKING

      von der Embse, U. A.; Hughes Aircraft Co. (International Foundation for Telemetering, 1983-10)
      The probe-to-orbiter data link for the Jovian mission uses a Manchester encoded BPSK waveform which is demodulated by the Galileo probe relay receiver. Signal acquisition and tracking consists of a sequential probability ratio signal search, frequency acquisition with a least-squares estimator, wide-band phase lock acquisition, and a self-regulating mode control. A discrete Fourier transform serves as the basic mechanism to generate the algorithms that provide this orderly transition to phase tracking. Acquisition and tracking is addressed in this paper with emphasis on key algorithms, rationale, and theorectical/ measured performance.
    • DIGITAL HILBERT TRANSFORMER FOR SINGLE-SIDEBAND GENERATION

      Udalov, Sergei; Axiomatix (International Foundation for Telemetering, 1983-10)
      This paper describes a digital real-time implementation of a Hilbert transformer for the generation of single-sideband signals (SSB’s). Design criteria for the transformer are presented and the experimental results are discussed for a typical voice-band channel having a nominal bandwidth of 300 to 3500 Hz. Techniques for generating two independent sidebands (ISB’s) on a single carrier are also described.
    • BIT SYNCHRONIZATION IN THE PRESENCE OF ASYMMETRIC CHANNEL NOISE

      Tsang, Chit-Sang; Lindsey, W. C.; LinCom Corporation; University of Southern California (International Foundation for Telemetering, 1983-10)
      Bit synchronization in the presence of asymmetric channel noise has not appeared in the open literature. It is the purpose of this paper to study the performance of a popular digital clock synchronizer, the Digital Data Transition Tracking Loop (DTTL), in the presence of asymmetric noise. A comparison of the DTTL and Cross Spectrum Synchronization Loop (CSSL) is also provided for special parameter values of greatest interest. Numerical results are presented for design of bit synchronizer in this environment.
    • SPACELAB HIGH DENSITY DIGITAL RECORDERS

      Blais, Richard A.; NASA (International Foundation for Telemetering, 1983-10)
      In 1979, NASA was faced with the problem of providing a ground facility magnetic tape recorder to store and retrieve serial Pulse Code Modulation (PCM) bit streams of up to 50 megabits per second (MBPS) which originated within Spacelab and its experiments. These recorders were required at the Kennedy Space Center (KSC), Johnson Space Center (JSC), and the Goddard Space Flight Center (GSFC). The Spacelab requirements presented a wide variety of problems which no existing “offthe- shelf” recorder could accommodate at the time. As a consequence, an extensive and complex performance specification was developed. This specification necessitated many advances in the “state-of-the-art” in the field of High Density Digital Recorders. The 9000 SL High Density Digital Recorders designed and fabricated by Thorn-EMI Technology, Inc., under contract to NASA, have successfully met or exceeded all of the Spacelab requirements as identified in the performance specification. These recorders demonstrate the latest in high density digital recording technology. This technology includes the capability of recording 50 MBPS of data with a bit error rate of better than 1 bit in 108, completely automatic bit synchronization, auto selection of the optimum replay equalization, and a data coding scheme giving up to 50% greater data packing density than traditional codes.
    • TOWARDS A UNIVERSAL DESIGN FOR ROV TELEMETRY VIA FIBER OPTICS

      Kono, Michael E.; Brininstool, Michael R.; Naval Ocean Systems Center (International Foundation for Telemetering, 1983-10)
      A brief description is presented on a current application of fiber optic technology to Remotely Operated Vehicle (ROV) design. Significant advantage is realized in terms of weight and space, EMI immunity, high bandwidth, and long length transmission capability. Current design practice utilized a standard graded index 50/125 micron telecommunications fiber “ruggedized” with a composite armor. On-going development seeks to make this cable element small and expendable while preserving the high bandwidth and low loss nature of the fiber. To free the system designer from mechanical considerations, the cable is pre-spooled and carried and deployed by the vehicle. Three dedicated communications channels are proposed on the single fiber by utilizing optical wavelength multiplexing.
    • INTEGRATED REALTIME SOFTWARE FOR BOTH AIRBORNE FLIGHT TEST SYSTEMS AND PCM GROUND STATIONS

      Trover, W. F.; Associate Director of Advanced Systems (International Foundation for Telemetering, 1983-10)
      Flight test activities can be completed quicker if the test engineers can evaluate test data in realtime on-board the aircraft or at the PCM ground station. Teledyne Controls is developing a software package for several customers that provides realtime EU data in several formats. Data presented to the test engineer includes: stacked or overlayed scrolling EU curves, limit exceedance tests and alarm generation, tabular EU data presentations and operator requested hardcopy of CRT presentations supplemented by the classical raw data strip chart recordings. Incorporated into this software are facilities permitting semi-automatic calibration of sensors installed in the aircraft during preflight operations as well as generation of tape headers for automatic PCM tape reading by the ground station. Other features include semi-automatic processing of sensor calibration data gathered in the calibration laboratory for entry into the ground station’s data base, and a software/hardware link coupling the data reduction software in the PCM ground station to the generation, loading and test of the data cycle map in the airborne PCM system.
    • THE INFLUENCE OF M ICROPROCESSORS ON SPACE (AIR/GROUND) SYSTEMS

      James, Lawrence P.; Systems Computer Operations (WSMC/RSCO) (International Foundation for Telemetering, 1983-10)
      This paper discusses current and future trends in technology for on-board processing and the impact of these trends upon the architecture and processing capabilities of the ground receiving stations. Both the advantages and disadvantages of increased digital processing and software controlled multiplexing are addressed from the ground station processing viewpoint. Increased on-board processing should lead to a decrease in telemetry data rates as well as a diminished role for the ground support stations. This is shown by the paper to be a false assumption. Indeed, the reverse of this supposition is explored in detail and shown to be correct.
    • NEW DIGITAL-INPUT TRANSMITTER FOR MISSILE TELEMETRY

      Rieger, James L.; Woodworth, Paul H.; Naval Weapons Center (International Foundation for Telemetering, 1983-10)
      Telemetry for aircraft and missiles has been in use by the military and its suppliers since the 1950’s, using a variety of frequencies and formats. The relative availability and versatility of digital electronics obviates use of pulse-code modulation (PCM) schemes, rather than analog-based formats used more commonly in the past. The digital-input transmitter described accepts binary format directly from a TTL source and has applicability in both standard telemetry and encrypted systems.
    • DESIGN OF A SETUP BUS EXPANSION INTERFACE

      Garcia, Michael S.; White Sands Missile Range (International Foundation for Telemetering, 1983-10)
      The Setup Bus Expansion Interface, a software selectable, 8 channel, digital demultiplexor was designed as an augmentation to the Telemetry Controller System (TMCS) at White Sands Missile Range (WSMR), New Mexico. The TMCS performs ‘front end’ synchronization and decommutation duties for the Telemetry Data Center at WSMR, utilizing EMR 700 series equipment hosted by a DEC PDP 11/44 computer/processor. The Setup Bus Expansion Interface has increased the capability of this system by transforming the single setup output bus of the host computer to a selectable 8 bus structure, allowing output of variable parameters to the 700 series equipment entirely from the host computer. The interface also offers dual selectable input on one channel to provide for the future implementation of a multiplex processor into the TMCS.
    • DIGITIZING HIGH-SPEED ANALOG DATA USING COMPUTERS

      Saulsberry, Garen; New Mexico State University (International Foundation for Telemetering, 1983-10)
      The Physical Science Laboratory (PSL) has developed processes for digitizing high-speed analog data using state-of-the-art equipment and software techniques. The Laboratory has resolved the problems encountered by integrating off-the-shelf equipment, PSL-designed interface units, and system application software to meet the specific needs of individual data collection and reduction systems.
    • CONVOLUTIONAL CODING/VITERBI DECODING OF PCM/FM

      Cox, T. F.; Nichols, M. H.; Naval Weapons Center (International Foundation for Telemetering, 1983-10)
      Tests were run with a binary PCM/FM transmission channel using limiter/discriminator detection and (7, 1/2) convolutional coding with Viterbi decoding. In all cases, soft decision decoding showed little or no improvement relative to hard decision, evidently because of the pops in the FM demodulator. Under optimum PCM/FM conditions, namely p-p deviation = 0.7 fs and IFBW = fs, the coding improvement at BER = 10^-6 was about 2.2 dB. The binary symbol rate in the transmission channel is fs. In the course of the test, it was discovered that with PCM/FM under optimum conditions, channel errors frequently occurred in pairs. This severely reduces the value of parity bit when used with uncoded PCM/FM and also degrades the Viterbi decoder performance by about 1 dB.
    • EHF COMMAND TECHNOLOGY

      Sacks, Louis H.; The Aerospace Corporation (International Foundation for Telemetering, 1983-10)
      The Air Force Satellite Control Facility is considering performing the command and telemetry functions at the EHF/SHF frequency bands (44 GHz uplink/21 GHz downlink). Among the factors affecting performance at the higher frequencies are the satellite and ground station antenna characteristics, receiver and power amplifier availability and weather effects. Of these factors weather effects, particularly rain, is the most severe and can result in temporary outages in the command and telemetry operation. It is recommended therefore that S-band operation be retained if greater than 99% link availability is required. TT&C operation at the EHF/SHF frequency bands could be achieved only if periodic weather outage and variable data rate transmission becomes acceptable.
    • DEVELOPING COMPUTERIZED, MOBILE TELEMETRY DATA PROCESSING SYSTEMS

      Cunningham, Mike; New Mexico State University (International Foundation for Telemetering, 1983-10)
      In today’s world, the fixed telemetry ground station is giving way to the mobile telemetry ground station. More and more systems are being developed to take advantage of mobility, allowing the ground station to be deployed to the testing area. To accomplish this, the Physical Science Laboratory (PSL) has developed methods to design mobile facilities to house modern, computerized telemetry stations that not only ensure equipment survivability, but also take into account the ergonomic considerations that are vital to operator performance.
    • SYSTEM ENGINEERING USING “TOY” COMPUTERS

      Mitchell, Steven W.; Sheets, K. Yvonne; ARGOSystems, Inc. (International Foundation for Telemetering, 1983-10)
      The current proliteration of microcomputers and software provides the system engineer and program manager a useful set of tools that can be adapted to support and enhance the program management effort. The functions that can be implemented effectively include scheduling, word processing, budgeting, limited data base applications, requirements tracing, document control, electronic mail/bulletin boards, and the tracking of contractual details. This paper describes strategies and architectures useful fo r implementing microcomputers into the program office environment. Also discussed is a software development methodology specifically tailored for the use at microcomputer applications software. * K. Yvonne Sheets is employed by Space Research, Inc., 440 Redondo Ave., Suite 202, Long Beach, Ca. 90814, and is under contract to ARGOSystams, Inc.
    • NEW ARCHITECTURE FOR A HIGH SPEED VERSATILE TELEMETRY/COMPUTER SYSTEM

      Strock, O. J. (Jud); Fairchild Weston Systems, Inc. (International Foundation for Telemetering, 1983-10)
      In telemetry/computer systems, there are significant trends toward: 1. Higher data rates, 2. More complex data formats, 3. Hardware pre-processing and compression, 4. Faster, more versatile interfaces to general-purpose computers. 5. The 32-bit computer system, 6. A small dedicated secondary computer for routine tasks, and 7. Smarter display devices and display servicing. This paper describes a system architecture which addresses each of these trends. The modular equipment provides a high-speed data throughput rate, even with complex formats, and is compatible with modern 32-bit computers.
    • USING THE STD BUS FOR ENCODER/DECODER SYSTEMS ABOARD A HIGH-ALTITUDE BALLOON PLATFORM

      Willis, Jim; Stabilized High Altitude Research Platform Physical Science Laboratory New Mexico State University Las Cruces (International Foundation for Telemetering, 1983-10)
      The Physical Science Laboratory (PSL) is developing a balloon-launched platform that will support a wide range of high-altitude projects. The Stabilized High Altitude Research Platform (SHARP) will house several on-board microprocessor-based subsystems to provide telemetry, command, and navigation data. Support for a wide variety of scientific experiments requires versatile electronic subsystems aboard the platform. Using the STD bus as a building block component, the Laboratory has designed and fabricated such subsystems. The STD bus, a standard interface throughout the computer industry, was chosen for the design because of its availability, ruggedness, versatility, and wide selection of compatible, off-the-shelf components.
    • A SOLID-STATE C-BAND POWER AMPLIFIER FOR COMMUNICATIONS SATELLITES

      LaPrade, J. Nicholas; RCA Astro-Electronics (International Foundation for Telemetering, 1983-10)
      A solid-state power amplifier now routinely replaces the traveling-wave tube amplifier in C-band communications satellites. The immediate benefit of superior performance is realized by increased transponder capacity. Long-term benefits of higher reliability and reduced production costs are also projected. This paper describes salient features of the first solid-state power amplifier to fully replace the traveling-wave tube amplifier in spaceborne transponders. The 8.5-watt, 60-dB gain amplifier employs a chain of gallium-arsenide field-effect transistors to provide a 160-MHz usable bandwidth within the 3.7- to 4.2-GHz downlink band. Data typical for this amplifier are presented. The key parameters of efficiency, intermodulation distortion, and phase effects are described in detail. The amplifier is being manufactured for numerous communications satellite programs. Aspects of reproducibility and automated testing at the various stages of amplifier production are addressed. Forty-eight amplifiers are now operational at geosynchronous altitude with several times that number scheduled for launch within the next few years.
    • SOLID STATE TECHNOLOGY APPLICABLE TO TRANSMITTERS

      Woo, Arthur; Bardai, Zahir; Leverich, Lyle (International Foundation for Telemetering, 1983-10)
    • DEEP SPACE OPTICAL COMMUNICATIONS EXPERIMENT

      Kinman, Peter; Katz, Joseph; Gagliardi, Robert; California Institute of Technology; University of Southern California (International Foundation for Telemetering, 1983-10)
      An optical communications experiment between a deep space vehicle and an earth terminal is under consideration for later in this decade. The experimental link would be incoherent (direct detection) and would employ two-way cooperative pointing. The deep space optical transceiver would ride piggyback on a spacecraft with an independent scientific objective. Thus, this optical transceiver is being designed for minimum spacecraft impact — specifically, low mass and low power. The choices of laser transmitter, coding/modulation scheme, and pointing mechanization are discussed. A representative telemetry link budget is presented.