• Characterization of Tape Recorder Flutter in an Airborne Environment

      Rieger, James L.; Naval Weapons Center (International Foundation for Telemetering, 1977-10)
      While many methods are known for measurement of tape recorder flutter, most are intended for a laboratory environment, or at worst for situations where environment is under positive control. When the tape recorder is placed in a dynamic environment which is the source of the data to be recorded, tape flutter has a significant effect on the data accuracy. This paper describes some of the consequences of such flutter, and a method for separating the effects of flutter in the recording process from those encountered in playback; such information is required for the characterization of airborne tape recorders and for validation of data obtained.
    • Comparison of Analog and Digital Transmissions for Multichannel Voice

      Birch, J. Neil; Office of the Secretary of Defense (International Foundation for Telemetering, 1977-10)
    • Comparison of SAW, CTD and Conventional Digital Devices

      O'Clock, G. D., Jr.; Rockwell International (International Foundation for Telemetering, 1977-10)
      Two solid state technologies, which help to make certain types of signal processors, bandpass filters and matched filters more realizable and practical, will be evaluated and compared in this paper. Both of the technologies of interest have been developing over the past nine years. Both approaches can provide design simplicity, small size and low cost potential on a volume production basis.
    • A Data Acquisition System Featuring On-Board Processing

      Endsley, Neil H.; Lee, Kyong H.; Maschhoff, Robert H.; Gulton Industries Inc./DSD (International Foundation for Telemetering, 1977-10)
      A data acquisition system for the telemetry data on the Technology Development Vehicle (TDV) program is presented. To meet the major experimental objectives of the TDV mission - the collection of high frequency vibration and acoustic data on a re-entry vehicle - required some unusual design approaches. It is shown that collection of this data requires a great deal of data compression. This was accomplished using a technique of on-board data processing - actually performing the first step of data reduction in flight. The entire data acquisition system is described in light of the requirements imposed by the data with emphasis on unusual problems and solutions. Results of ground tests in an anechoic chamber are presented, and a brief discussion of the errors involved in onboard processing is given.
    • Design Concepts for a Highly Reliable Multimicroprocessor System for Communication Satellites

      Plisson, Francois; MATRA S. A. (International Foundation for Telemetering, 1977-10)
      Over past years, the microprocessors have been used widely and efficiently for many applications. Some of them have become industrial standards, and the question arised how to use them most efficiently for space applications. The paper describes the design concepts which have directed the study and the breadboarding of a trimicroprocessor system and its monitoring software. These concepts have been traded off for reaching a high system overall availability and flexibility. The multiprocessor is organized around C-MOS microprocessors and a time shared/common bus, designed for reliable operations. The monitoring software is especially developed to yield a triple redundancy for critical (i.e. mission success dependent) software functions and to assure the mutual failure independency of the application programs. On board telecommunication satellites, the multiprocessor structure have been found better suited for reliability, probability of mission interruptions and its capability of degraded operation when it was compared to a classical stand by redundant monoprocessor array. At the end of the year, the triprocessor system will be integrated into a satellite attitude control simulator for a system closed-loop test with an air bearing table and actual satellite equipments.
    • Detection of Scattered Optical Fields with Focal Plane Ring Detectors

      Vilnrotter, Victor A.; Hughes Aircraft Company (International Foundation for Telemetering, 1977-10)
      It is demonstrated that when communicating through scattering channels order-ofmagnitude improvement in system performance is possible by employing focal-plane processing techniques to recover some of the scattered radiation. Maximum a-posteriori and suboptimal system structures are derived and their performance evaluated. System sensitivity to the errors in the optimal weighting functions is discussed.
    • The Development of a Satellite On-Board Microcomputer

      Eardley, Deryck W.; British Aircraft Corporation (International Foundation for Telemetering, 1977-10)
      The paper describes a miniaturized computer for space use that is being developed under a contract from Intelsat. An all CMOS design is used with the corresponding low power and high speed associated with CMOS. Extensive use is made of LSI and the computer is based on the Intersil or Harris 6100 microprocessor. This has the same architecture as the PDP8-E and the extensive range of DEC PDP8-E software can be used. Provision has been made for both serial and parallel input/output ports. A development prototype is described that has serial and parallel ports. The associated memory is expansible up to 32K words in 2K blocks. RAM or PROM can be used or interchanged in blocks of 256 words. A programmable timer is included for real time applications. A bench model of the computer is also described which is made for program development. It is not to the same environmental standards as the development prototype but has the same facilities together with a control panel and provision for a teletype. The use of the Bench Model for software development is described.
    • Double Quadriphase Modulation/Demodulation Technique for Three-Channel Communication Link

      Alem, Waddah K.; Axiomatic (International Foundation for Telemetering, 1977-10)
      A modulation technique for a three-channel communication link is introduced. The structure of the modulator is such as to form an unbalanced quadriphase signal wherein the high rate data stream is bi-phase modulated on the in-phase carrier component, while the sum of the two lower rate signals is bi-phase modulated on the quadrature component of the same carrier. The sum of the two lower signals is, in turn, formed by modulating with the respective data streams the in-phase and the quadrature components of a square wave subcarrier. At the demodulator, the tracking of the carrier and the subcarrier is performed by two independent Costas loops. The demodulation of the high data rate signal is carried out after establishing the carrier reference signal, while the lower rate signals are demodulated after the subcarrier loop recovers the subcarrier. In this paper, the performance of the two loops is analyzed and the expressions for the tracking errors are derived. Finally, a numerical example pertaining to the Space Shuttle-to-TDRS Ku-band link is presented for illustration.
    • ECM/ECCM Effects on Voice Transmissions

      Buskirk, Ronald L.; Nossen, Edward J.; Government Communications Systems (International Foundation for Telemetering, 1977-10)
      An evaluation methodology for conventional and ECCM voice communications is presented, wherein intelligibility of the received message rather than error rate or signal-to-noise ratio is the quantity measured. This allows the engineer to include the psychoacoustic phenomena of a human listener in his system design considerations. Analyses have been performed which allow transformation of speech articulation test results into data more meaningful to the communications engineer. Since message intelligibility is established after baseband reconstruction of the voice signal, this method is universally applicable to most voice transmissions. It is insensitive to the nature of the medium, modulation, and interference sources. Examples are presented showing applications of these guidelines to the design of frequency hopping radios. Tests run on a simulator confirm the analyses. A sample tape is available to demonstrate some of the effects.
    • EDP Tape - Performance and Reliability - Past, Present and Future

      Fiori, J. J.; General Services Administration (International Foundation for Telemetering, 1977-10)
      This report was prepared by the Electronics Division, Federal Supply Service of the General Services Administration and is intended to share with all interested parties, the information and experiences with EDP Computer Tape gathered by the GSA since 1966, when it assumed the responsibility to support procurement of these items for all Federal agencies. It is hoped that the information contained herein will be of benefit to the tape-using community and will lead to a better understanding of the Government's role in providing high quality computer tape to meet current and future data storage applications. The General Services Administration's active involvement in the program to supply high quality computer tape to Government agencies was initiated through the development of Interim Federal Specification W-T-0051. The specification was based upon technical requirements received from the tape-using community and inputs supplied by the tape industry. GSA Laboratory facilities are utilized for product qualification testing, specification development testing and quality assurance testing. It is from all of these sources that the data presented herein was gathered. To establish some kind of perspective, it should be noted that these results are representative of the over 25,000 reels of computer tape sampled, tested and evaluated annually by GSA in support of annual procurement volumes of approximately 1 million reels. In addition to presenting quantitative data showing how tape quality levels have increased over the past four years, the report also addresses past problems and recent improvements, and further attempts to identify those remaining areas in which the tape industry must concentrate its future developments.
    • Encoding of Telemetry Data in a Standard Video Channel

      Rieger, James L.; Naval Weapons Center (International Foundation for Telemetering, 1977-10)
      Various methods for compressing of a television image to fit a channel of reduced bandwidth are available; most are difficult and/or expensive to use, and many degrade the resulting picture appreciably. This paper describes an alternative method of placing the signals which accompany the picture within the passband of a picture, and separating them again at the receiving end with minimum crosstalk and picture degradation.
    • Experimental Comparison of Pulse Code Modulation Codes for Magnetic Recording

      Law, E. L.; Pacific Missile Test Center (International Foundation for Telemetering, 1977-10)
      The bit error probability (BEP) versus signal-to-noise ratio (SNR) was experimentally determined for Non-Return-to-Zero-Level (NRZ-L), Bi-Phase-Level (BIΦ/-L), Delay Modulation (DM) and Miller Squared (M²) codes for a bandpass channel. This was done by passing the data through a 400 Hz to 500 kHz Bessel bandpass filter and linearly adding noise. The power spectral density of the noise was shaped to match the noise out of an analog magnetic tape recorder running at 30 inches per second (in./s). This provided a simulation of an optimum wideband 2.0 MHz tape recorder running at 30 in./s (no flutter, tape dropouts, etc.). The bit rate, pattern, and code to be tested were then selected. The SNR was varied until the bit error probability was approximately 10⁻⁶ With a commercial Pulse Code Modulation (PCM) bit synchronizer with a "good" dc restorer and a pseudo-random pattern at 1.0 megabits per second (Mb/s) (33.3 kilobits per inch (kb/in.) equivalent packing density), NRZ-L had a 4 dB SNR advantage over DM and a 14 dB advantage over BIΦ/-L for a BEP of 10⁻⁶ through the bandpass channel. At 1.5 Mb/s, NRZL had a 6 dB advantage over DM and a 10⁻⁶ BEP was not achievable with BIΦ/-L coding. For a synchronizer with no dc restoration NRZ-L had only a 1 dB advantage over DM at 1.0 Mb/s and also only a 1 dB advantage at 1.5 Mb/s. M² gave the same results as DM for pseudo-random data. However, M² was relatively insensitive to patterns while DM and NRZ-L required a higher SNR with a "good" dc restorer and lost synchronization completely with no dc restorer for worst case 16-bit repeating patterns.
    • Fiber Optical System Performance with Avalanche Gain Detection

      Sorensen, Alfred N.; California State University (International Foundation for Telemetering, 1977-10)
      The purpose of this paper is to consider optical system performance for selected digital signal formats when shot noise limited avalanche photodetection is implemented. Performance characteristics for binary on-off keyed (OOK) and pulse position modulation (PPM) are given, in addition to M-ary PPM and PAM.
    • A Frequency Modulated S-Band Telemetry Transmitter

      Homa, M. L.; Ward, J. H., Jr.; E-Systems (International Foundation for Telemetering, 1977-10)
      The need to efficiently collect data from remote locations has resulted in the widespread use of radio frequency telemetry. This paper addresses the requirements, considerations, and implementation of such a system. Since many components of a telemetry link are subjected to harsh operating environments, considerations of system constraints imposed on the transmitter by these conditions will be presented. Several design approaches of an S-Band frequency modulated telemetry transmitter will be offered, and tradeoffs associated with each discussed. Having selected the most desirable transmitter design approach a pictorial display of the hardware used to fulfill the requirements will be presented along with measured performance data. The key circuits discussed will be an S-Band VCO, parametric divider, buffer/power amplifier, and stabilizer/modulator. The RF circuits employ microwave integrated circuit construction while the stabilizer/modulator utilizes thin and thick film hybrid technology. Extensive use was made of computer analysis resulting in uniformly producible circuits that provide good correlation between measured and specified performance. This helped to produce a 25% reduction in production cost over the previous discrete component design of 1969 vintage. Basic circuit design lends itself well to special mechanical configurations, as well as flexibility in modulation formats and RF power output levels. By using the computer aided design approach, five percent RF bandwidths were realized which would enable the transmitter to be frequency agile for secure or multivehicle telemetry.
    • A High Data Rate Recorder/Reproducer

      Brobst, R. E.; Odetics, Inc. (International Foundation for Telemetering, 1977-10)
      A High Data Rate Recorder (HDRR) has been developed under contract with Engins Matra, France, to be used in the European Spacelab. Engins Matra is responsible for the design and testing of the Command and Data Management System (CDMS). The HDRR is part of the CDMS which performs on-board data processing, multiplexing and storage. The Spacelab is a primary payload of the U. S. Space Shuttle Orbiter. The HDRR interfaces with the Spacelab High Rate Multiplexer, which, in turn, provides the inputs to the Tracking Data Relay Satellite (TDRS) down-link system for transmission to the ground. The HDRR is capable of recording and reproducing at a maximum rate of 32 Mb/s. The total continuous record time allowed at this rate is 20 minutes. Thus a total of 3.84 x 10¹⁰ bits can be stored. The HDRR has a versatile command and data interface that allows for recording at any rate between 1 Mb/s and 32 Mb/s. Reproduction can be performed at 2 Mb/s, 4 Mb/s, and any rate between 8 and 32 Mb/s.
    • Impact of Intelligent Systems on the Telecommunication Interface

      Chien, R. T. (International Foundation for Telemetering, 1977-10)
      In the next ten years, there will be a great deal of development in the area of theory and applications of intelligent systems. Some of these systems will be related to industrial automation in manufacturing and some others will be related to automation in the cockpit of aircrafts. In this paper, a major project in computer aided decision-making (CADM) will be examined in detail. This CADM System serves as a potential co-pilot for flight operations and proposed to handle many of the routine duties of the pilot. It assists the pilot in data-processing, signal detection, flight planning, navigation, obstacle avoidance, and interaction with ground and air communicators. The purpose of this paper is to examine the new environment and the impact it has in telecommunication needs in the direction of future research and development. A movie will be shown of the project demonstrations.
    • An Integrated Error Correcting/Pseudo Random Communication System

      Schiff, Maurice L.; ITT Aerospace Optical Division (International Foundation for Telemetering, 1977-10)
      This paper describes a pseudo random (PN) communication system with an integral error correcting code. The error codes are again based on maximal length sequences and simultaneously provide coding gain with bandwidth expansion. A basic modem starting at 2400 bps data rate and expanded to a 5 Mbps chip rate is described. Theoretical and hardware test results are presented to verify the concepts. Finally, synchronization of this system is discussed. A PN range extension concept is developed which improves the acquisition time with only a trivial increase in system complexity.
    • International Telemetering Conference Proceedings, Volume 13 (1977)

      International Foundation for Telemetering, 1977-10
    • JTIDS Modular Design to Use SAW Devices

      Grasse, Charles L.; Teledyne MEC (International Foundation for Telemetering, 1977-10)
      The Joint Tactical Information Distribution System (JTIDS) concept is designed to integrate the military's needs for communication, navigation and identification equipments into a cost-effective avionic suite. A key element to be used in achieving these goals is the surface acoustic wave (SAW) bandpass filter...in the form of a bandwidth selectable module. In order to satisfy the JTIDS requirements of today, as well as the Tactical Information Exchange Systems (TIES) of the future, it is necessary to utilize state-of-the-art SAW resonator/filter designs ... in conjunction with more conventional SAW bandpass filter technology. It is this approach that will make possible the quality performance required in a small, low cost module.
    • Modeling of Optical Propagation in the Underwater Environment

      Karp, Cherman; Naval Ocean Systems Center (International Foundation for Telemetering, 1977-10)