• A-M/AGC Weighted Pre-Detection Diversity Combining

      Hill, E. R.; Pacific Missile Test Center (International Foundation for Telemetering, 1977-10)
      A method has been proposed for improving the performance of automatic gain control (agc) weighted diversity combiners in the presence of fast fading radiofrequency (rf) signals by use of the amplitude modulation (a-m)(detected linear intermediate-frequency (i-f) envelope) in addition to the agc voltage to weight the combiner. Also suggested was a method for selecting the channel with the best signal-tonoise ratio (SNR) by use of the a-m and agc voltages. Experimental hardware has been constructed for evaluation of three configurations: an a-m/agc weighted combiner; an a-m/agc based selector; and an a-m/agc combiner/selector where the criterion for combine or select is determined by the phase error between the two channels. An experimental study was also conducted of the phase-locked loop (PLL) to determine the best configuration and parameter values for the combiner application (where relatively large phase errors are permissible). Data were taken under laboratory and operational (Vandenberg Air Force Base) conditions and are compared with data taken with a commercial agc weighted combiner.
    • ACMR/I System

      Parker, J.; Cubic Corp. (International Foundation for Telemetering, 1977-10)
      The instrumentation system described provides real-time attitude and position data on 8 high-dynamic fighter aircraft and position data on 12 additional cooperative targets. Position data is derived from multilateration range measurements using FM-CW phasecomparison techniques. Attitude and acceleration data is obtained from a strap-down inertial system initialized by the ranging system. Digital data is transmitted to and from the target by frequency shift keying of the ranging carrier. A multiprocessor ground computer using Kalman filter techniques provides a total state vector for each participant at a rate of 10 per second. The multiprocessor also provides real-time missile simulation for performance scoring. The Display and Debriefing Subsystem provides real-time computer-drawn pseudo three-dimensional display of the aircraft, total replay capability, and control of the entire system from the operator's console.
    • Adaptive Array Control Concepts for TDRSS

      DuPree, J. E.; TRW Systems (International Foundation for Telemetering, 1977-10)
      The Tracking and Data Relay Satellite System (TDRSS) will use an Adaptive Ground Instrumented Phased Array(AGIPA) system for remote beamforming and tracking of low-orbit user spacecraft. This paper introduces the control concepts involved in its beamforming, tracking, and calibration. These concepts are related to the Kalman filter. Several suboptimal, but attractive, tradeoff options are discussed.
    • The Apollo VHF Ranging System

      Nossen, Edward J.; Government Communications Systems RCA (International Foundation for Telemetering, 1977-10)
      Redundancy of functions on manned space flights has been an important concept for crew safety. However, a redundant system generally implies doubled weight - a luxury that can not easily be afforded on a spacecraft. The Apollo Command Module- Lunar Module rendezvous mission was performed with the rendezvous radar system. RCA developed a VHF Ranging System, which permitted the voice/telemetry radios to be adapted as a backup for the radar's ranging function at relatively low additional weight. The proven accuracy and reliability of the VHF Ranging System resulted in its selection as the sole rendezvous sensor for subsequent earth orbital manned missions. The constraints imposed by existing radios are discussed, the ranging options and selected implementation are described, and the system accuracy is reviewed.
    • Application of the Global Positioning System (GPS) to Space Shuttle Navigation

      Nilsen, Peter W.; Axiomatic (International Foundation for Telemetering, 1977-10)
      The present baseline Space Shuttle navigation system is comprised of several separate subsystems: TDRSS doppler ranging, TACAN (Tactical Air Navigation), MSBLS (Microwave Scanning Beam Landing System), and ground tracking. With the advent of the DOD development of the GPS, it may be possible to replace several of these subsystems with an on-board GPS navigation system. However, the Shuttle signal dynamics and environmental considerations impose unique and severe requirements for a GPS navigation system. Consequently, a preliminary study has been conducted to define requirements and configure candidate GPS systems for the Shuttle navigation function. Three configurations have been considered: an early test/demonstration system, which could be flown on early OFTs (Orbital Flight Tests), an interim system having greater capability but still not having full operational capability, and, finally, a fully operational system. A description of the test/demonstration and interim systems and the results of performance analyses are given. These preliminary results indicate that a GPS navigation accuracy greater than that obtained from the baseline system can be obtained for the orbital and de-orbit phases of the Shuttle mission.
    • The Application of the NAVSTAR Global Positioning System to the Evaluation of the Next Generation Long Range Ballistic Missiles

      Moses, Jack; Magnavox Government and Industrial Electronics Co. (International Foundation for Telemetering, 1977-10)
      The NAVSTAR Global Positioning System (GPS) is a joint services program currently undergoing concept validation. The program is managed by the Air Force with participation by the Navy, Army, Marines, and Defense Mapping Agency. When fully deployed, GPS will provide highly precise position and velocity to a variety of users. The Magnavox Advanced Products Division, under several funded contract activities, is participating in the development of several user equipments and studying the application to many others. This paper discusses the results of a study performed for the Space and Missile Test and Evaluation Center (SAMTEC) Vandenberg AFB to determine the feasibility and capability of the use of the NAVSTAR Global Positioning System as a tracking instrument and guidance evaluation system for the next generation ballistic missiles. The paper examines three primary approaches to the missile tracking problem using GPS. Recommendations for missile instrumentation are provided based upon studies in areas such as mission scenario, environmental factors, systems requirements and constraints, and configuration analysis.
    • Approximate Design Formulae and Procedures for Designing Hybrid Telemetry Systems Using an FM Carrier

      Lantz, Norman F.; Nichols, Myron H.; The Aerospace Corporation (International Foundation for Telemetering, 1977-10)
      Approximate engineering design formulae are presented. These are based on Rice's model of pop plus fluctuation noise in FM receivers. Several design examples are given. One hybrid system contains a baseband acoustic signal plus a PCM/FM subcarrier and another system contains a baseband PCM signal plus two PCM/FM subcarriers. Depending on carrier modulation parameters, the design formulae show that either pop noise or fluctuation noise in the carrier discriminator output may predominate in determining the bit error probability in the baseband and/or subcarrier services. Examples of each are given. The hybrid systems mentioned above were simulated in the laboratory. Test results are presented and show satisfactory agreement with the design formulae.
    • ARIA - An Inside Look

      Gast, Robert H., Jr.; Wright-Patterson AFB (International Foundation for Telemetering, 1977-10)
      The Advanced Range Instrumentation Aircraft (ARIA) is a mobile telemetry platform originally designed in the mid 1960s to meet the challenging voice and telemetry support requirements of the NASA Apollo Program. Since its inception, the telemetry instrumentation has been continually updated and improved. Each telemetry subsystem on the aircraft, Antenna, RF, Communications, Recording/Timing, and Data Separation is examined to provide an overview of the present capabilities. Additionally, signal processing methods employed for the realtime retransmission of analog and digital telemetry data are examined including the use of a minicomputer for digital signal processing.
    • Band Spread Effect of a Doppler Miss Distance Measurement System

      Hu, Anthony S.; New Mexico State University (International Foundation for Telemetering, 1977-10)
      Single path Doppler missile scoring systems encounter band spread problem at short miss distances. This paper examines the band spread effect by using a computer simulation method and a hardware-in-the-loop simulation method. Results of both methods are compared.
    • Best Source Selector System

      Alday, J. R.; Fleet Analysis Center (International Foundation for Telemetering, 1977-10)
      This system was developed in order to fulfill a need existing at the Fleet Analysis Center (FLTAC) Field Station-Caribbean, Telemetry Site at Roosevelt Roads, Puerto Rico. At the Field Station there exists four 16-foot diameter, two 8-foot diameter missile telemetry tracking systems plus a four frequency downlink Airborne Data Link (ADL) aircraft. With associated receivers, total number of video sources can be on the order of forty. Although all sources are recorded on magnetic tape and can be played back, only one or two sources can be displayed on high speed oscillographs simultaneously in "real time." The Best Source Selector System (BSSS) was developed in order to display, in real time, a continuous composite missile telemetry record which may consist of several individual sources. This System has been used continuously for the past three years for all missile telemetry operations at the Atlantic Fleet Weapons Training Facility (AFWTF), Puerto Rico. It has saved many man-hours of labor, searching tapes for bits and pieces of data and consequently, preliminary flight analysis and reporting to firing units (QUICKREPS) have been speeded up many fold.
    • 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.