• COORDINATION OF TELEMETRY STANDARDS

      Muller, Ronald M.; Telemetering Standards Coordination Committee (International Foundation for Telemetering, 1973-10)
    • CROSSPLAY COMPATIBILITY OF WIDE-BAND TAPE RECORDER/REPRODUCERS

      Hartzler, F. R.; Hust, D. R.; Heberling, E. D.; Naval Missile Center (International Foundation for Telemetering, 1973-10)
      This paper describes the procedure and results of a series of tests on a cross section of tape recorders to determine the effects of record bias and record signal level on the quality of data recorded in the Pre-D (predetection) mode. FM (frequency modulation) and PCM (pulse code modulation) formats were used in the study. The tests were performed on tape recorders at five test sites to determine the effects of crossplay under typical operating conditions. The results are summarized and possible methods of improving crossplay data quality are suggested.
    • CRYSTAL-CONTROLLED HIGH-G TRANSMITTER

      Lange, Kenneth L.; Schell, Max V.; Hewlett-Packard; Sandia Laboratories (International Foundation for Telemetering, 1973-10)
      Continuous telemetering during and after a 10,000 to 16,000g shock pulse experienced by the telemeter is a requirement that is frequently not met. In most cases a free-running oscillator is used in the transmitter while a very wide band receiver is used to acquire and provide leeway for the drifting and shifting RF signals.
    • THE D.O.T. CHANNEL SIMULATION AND MODEM TEST FACILITY

      Buck, R. E.; Frasco, L. A.; Salwen, H. C.; Transportation Systems Center; Proteon Associates (International Foundation for Telemetering, 1973-10)
      The characteristics and capabilities of a channel measurement and simulation facility are described. This facility has been established at the U. S. Department of Transportation, Transportation Systems Center. The system employs a RAKE type channel measurement system and a compatible digital equivalent tapped delay line channel simulator. The equipment has been used for the evaluation of digital communications problems created by the urban environment. It is currently being used to investigate the performance of modems under a variety of propagation conditions.
    • DATA RELIABILITY

      Powers, S.G.; Radiation (International Foundation for Telemetering, 1973-10)
      In this paper the problem of achieving reliable digital information transfer in the presence of data errors is addressed. The approach taken is to reject data which is suspected of being in error under the philosophy that it is better to miss data than to receive it incorrectly. To this end, error detection mechanisms are considered and their performance compared for a specific application. The mechanisms are thresholding, error detection coding, waveform error detection and feedback. It is shown that error detection coding is the most effective, followed by feedback, thresholding, then waveform error detection. The results are summarized in Tables I and II. These tables give the undetected word error rate and missed word rates for the techniques considered. The application which originally inspired this work is the use of time-division multiplexing to transfer mission-critical data on the B-1 aircraft.
    • THE DESIGN OF A SECOND GENERATION YAWSONDE

      Clay, Wallace H.; Mermagen, William H.; Ballistic Research Laboratories (International Foundation for Telemetering, 1973-10)
      Improvements have been incorporated into existing yawsonde telemeters to facilitate ground reduction of extensive quantities of data. The main area of improvement has been in the design of the amplifier so that solar pulses of constant amplitude and constant width can be transmitted to ground receiving stations. The new amplifier design makes it possible to reduce the solar pulse data on board the projectile itself providing solar aspect angle as a function of time of flight in binary coded form at the transmitter. Such on-board, real time motional data could be used in a command/control system to enhance the accuracy of artillery fire.
    • A DISCRETE ADDRESS BEACON SYSTEM

      Israel, David R.; Federal Aviation Administration (International Foundation for Telemetering, 1973-10)
      The two most basic requirements for air traffic control are surveillance and communications. The surveillance system in use today is the Air Traffic Control Radar Beacon System. It is based on World War II technology and is experiencing severe difficulties as the number of aircraft carrying transponders increases. This paper outlines the present FAA program to develop a new surveillance system which will eliminate the problems, will be compatible with the existing system and will also provide a digital data-link for collision avoidance and air traffic control purposes.
    • GSFC STANDARDS PROGRAM

      Poland, William B., JR.; National Aeronautics and Space Administration (International Foundation for Telemetering, 1973-10)
    • A HIGH CAPACITY, HIGH DATA RATE INSTRUMENTATION TAPE RECORDER SYSTEM

      Bessette, O. E.; Radio Corporation of America Recording Systems (International Foundation for Telemetering, 1973-10)
      A 240-megabit/second, serial bit stream recording system using a longitudinal (fixed-head) magnetic recording technique called HDMR (High Density Multitrack Recording) has been developed. This system provides maximum bits per square inch of tape at reliable in-track packing densities. Unique “unitized” fabrication techniques have been used to construct single stack magnetic heads (record/play on the same head) at track densities of over 100 tracks per inch. Commercially available tape is accommodated by the use of error detection and correction. HDMR technology, applied to the implementation of a typical ground instrumentation recording system, allows key performance parameters of: 240 Mb/s serial data input, 108 in/s tape speed, a 142-track head, a bit error rate of 1 x 10^-6 and 240 Mb/s serial data output.
    • HIGH DENSITY PCM MAGNETIC TAPE RECORDING

      Wells, Jon B.; Bell & Howell (International Foundation for Telemetering, 1973-10)
      The Bell & Howell Enhanced-NRZ™ recording reproducing technique for bit packing densities up to 40,000 per track inch is described in this paper. Utilization of the pulse code modulation format of Enhanced-NRZ achieves this high density with a bit error rate of one in ten million. Bell & Howell’s standard VR-3700B instrumentation tape recorder and wideband instrumentation recording tape are used. This same technique permits parallel recording of data rates up to 10 megabits per second at a tape speed of 120 in./s. The merits of the unique encoding/decoding method, factors affecting bit error rate, and future opportunities for development are discussed.
    • A HIGH SPEED AIRBORNE DATA ACQUISITION AND CONTROL SYSTEM WITH AN INTEGRATED DIGITAL COMPUTER

      Trover, William F.; Teledyne Controls Company (International Foundation for Telemetering, 1973-10)
      AIFTDS-4000 has been developed as a modularly expandable instrumentation and control system primarily for use in aircraft and system flight test. The bidirectional data processing capacity of Remote Multiplexer/Demultiplexer Unit, however, permits the system to be applied to data processing and control loop functions as well as the classical role of a data gathering system. The basic system was developed for NASA-FRC under three different contracts; NAS4-1848 (the ACS and RMDU’s), NAS4-1940 (the integrated signal conditioner cards) and, NAS4-1943 (the expanded test set). The system comprises Airborne Hardware, Ground Support Equipment and Software. The Airborne Hardware is divided into two major elements; The Airborne Computing System (ACS), and the Remote Multiplexer/Demultiplexer Unit (RMDU). Ground Support Equipment is presently restricted to the ACS Test Set (ACS/TS) which permits total checkout of the ACS without the RMDU’s or checkout of the full AIFTDS, as well as performing the function of an autonomous mini-data reduction ground station and the Portable Address Generator which permits testing of one RMDU (or one zone of the airplane) without the ACS or the ACS/TS. Software may be grouped into System Checkout and Diagnostic Software, Flight Test Program Software and Quick Look/Reduction Software. The prototype AIFTDS-4000 was qualified in two stages; the RMDU was qualified in October 1972 with the ACS qualified in April 1973. The Expanded Test Set and supporting software were delivered in May 1973.
    • THE INFLUENCE OF CARRIER FREQUENCY ON SNR FOR FM SYSTEMS

      Monson J. E.; Harvey Mudd College (International Foundation for Telemetering, 1973-10)
      The influence of carrier frequency on broadband signal-to-noise ratio is derived for a frequency modulated tape recording system. Optimum signal-to-noise performance occurs at the value of carrier frequency where the carrier-to-noise ratio is falling at 6 dB/octave. Signal-to-noise ratio is relatively insensitive to changes in carrier frequency about the optimum value.
    • INTERFEROMETER SIGNAL DEMODULATION IMPROVES TRACKING SENSITIVITY

      Cooper, William K.; New Mexico State University (International Foundation for Telemetering, 1973-10)
      A considerable improvement in signal to noise ratio has been achieved in narrow band interferometer trackers by demodulating the telemetry signal prior to the final stage of i-f amplification. This system has an effective signal bandwidth much greater than the noise bandwidth. Signal to noise improvements of 10 dB are typical.
    • International Telemetering Conference Proceedings, Volume 09 (1973)

      International Foundation for Telemetering, 1973-10
    • MEASURING TERRESTRIAL RADIO FREQUENCY INTERFERENCE AT ORBIT ALTITUDES

      Bayol, Martin E.; Locke, Paul A.; National Scientific Laboratories, Inc. (International Foundation for Telemetering, 1973-10)
      Satellite systems, by virtue of their large terrestrial fields of view, may be exposed to a great many man-made radio signals the aggregate effects of which can be deleterious to satellite receivers. An experiment has been designed to measure and characterize such man-made interference at orbital altitudes. The experiment, as designed, requires dedicated hardware on a spacecraft of specified orbit and will measure (within the frequency range of 400 MHz to 12.4 GHz) peak levels of interference in cells dimensioned in space, time, and frequency. The experiment will provide data indicative of some of the statistical characteristics of interference levels at satellite orbital altitudes and will provide designers of satellite communications links with new facilities for the prediction and prevention of interference problems, and should provide a considerable data base for use in long range planning of spectrum utilization.
    • MECHANICAL DESIGN CONSIDERATIONS FOR A PROJECTILE TM

      Williams, Don, JR.; Sandia Laboratories (International Foundation for Telemetering, 1973-10)
      The mechanical packaging necessary to protect electronic packages from the gun firing accelerations is the key to a successful telemetry system. All components and wires must be given structural support, usually by the use of potting materials. Where the accelerations come from and two successful packaging methods are described.
    • MILITARY COMMUNICATION SATELLITES

      Wall, Virgil W.; The Aerospace Corporation (International Foundation for Telemetering, 1973-10)
    • A MULTI-PURPOSE, DUAL-CHANNEL MODEM FOR C/No THRESHOLD

      Baghdady, Elie J.; Info Systems (International Foundation for Telemetering, 1973-10)
      A description is given of a newly developed modem based on the synthesis of a constant-envelope quadra-phase signal with dual-channel frequencydivision multiplexing of analogvoice with data, data with data, time code With data, ranging signal with d:Ata, etc. The technique is capable of providing low-threshold operation down to carrier power-to-(noice power density) ratios, about 40 db, and includes a built-in, on-line measurement and display of the C/N(o) for quantitative performance monitoring purposes.
    • MULTIMEGABIT OPERATION MULTIPLEXER SYSTEM

      Giri, Ronald R.; Maxwell, Marvin S.; Radiation; Goddard Space Flight Center (International Foundation for Telemetering, 1973-10)
      The Multimegabit Operation Multiplexer System (MOMS) is a high data rate PCM telemetry unit capable of sampling and encoding 60 scanning radiometer and 4 vidicon channels at 250 kilosamples/second and 5 megasamples/second, respectively. This sampling capacity plus the 7-bit quantization requires a total throughput rate of 40 megasamples/second and 280 megabits/second. To produce these rates efficiently, the system was divided into a pair of identical 140-megabit blocks. A low-power 20-MHz analog multiplexer and analog-to-digital converter were developed together with a video sample-and-hold that features an aperture time error of less than 50 picoseconds. Breadboard testing of these basic building blocks confirmed the design prediction that the total system would consume 27 watts of power. Two 140-megabit output ports are suitable for quadraphase modulation.
    • MULTISTATE ANALOG AND DIGITAL INTEGRATED CIRCUITS

      Abraham, George; US Naval Research Laboratory (International Foundation for Telemetering, 1973-10)
      Several independent physical phenomena in unipolar and bipolar semiconductor pn junction devices and integrated structures lead to voltage and current-controlled negative resistance without the use of external feedback. These include avalanche breakdown, quantum mechanical tunneling, and minority carrier storage. Two complementary types of negative resistances may be utilized as a basis for generating multistable energy levels. The number of stable states and their relative spacings can be readily varied. Without negative resistance interaction, M+1 stable states can be generated where M is the number of negative resistance devices involved. With negative resistance interactions, additional multistability occurs, resulting in a total number of (M+1) + (M-1)!stable states. S-S, N-N, and S-N interactions are analyzed. In the latter case, complementary negative resistances can be made to annihilate each other. Multistate tunnel and avalanche negative resistances have been made to occur in single devices resulting in tristable, quadristable and higher order energy levels. Variable radix counters, oscillators, frequency dividers, and high density memory elements have been fabricated both as hybrid and monolithic integrated circuits.