• Electronic Display Technologies for Telemetry Data Presentation

      Rochette, Marc; McIntosh, Dale; INFOTEC Development, Inc. (International Foundation for Telemetering, 1980-10)
      The expanding display market provides almost unlimited options for the potential user. This paper presents a methodology for selecting display technologies for the presentation of telemetry data. An overview of current state-of-the-art electronic display technologies is presented and the general characteristics of telemetry data are derived. The requirements for displaying the telemetry data are then considered in light of the attributes of the display technologies and appropriate options are presented.
    • Man/Machine Interface Definition

      Sheets, K. Y.; Taverney, Thomas; INFOTEC Development, Inc. (International Foundation for Telemetering, 1980-10)
      As an integral part of developing operational concepts for large scale command and control centers it is necessary to make assessments of the control and display requirements and the personnel subsystem. A methodology for detailing the man/machine requirements has been developed which can assist in the design of these control centers. The proposed methodology is extremely flexible and has been used for several different types of problems. The analysis begins with the functional activities to be performed and carries them through to the specification of the display requirements for each operator position and the manpower necessary to support the operation of the control center. An important aspect of the methodology is that it allows traceability of the original requirements throughout the process.
    • Digital Transmission System Implementation for the American Satellite Company

      Habib, Edmund J.; Mittal, Sham; American Satellite Corporation (International Foundation for Telemetering, 1980-10)
      Planning for the implementation of the digital transmission system began in 1975. Conceptual design was completed in late 1976 which consisted of three major elements; (1) analogged digital conversion equipment for the communication central offices, (2) time division multiple access system and earth station networking, and (3) digital microwave equipment for interconnecting the central offices to the earth station. Two approaches were considered for the voice analog to digital conversion equipment. These were CVSD (delta modulation technique) and specialized adaptive PCM technique. Contracts for the hardware were awarded in early 1978 for all the major elements. Installation was completed in mid-1980 and the system was made operational in August 1980. Unique features of the system are: (1) 64 MBPS TDMA first rate transmission at a BER of the order of 10-8, (2) digital microwave system incorporating state-of-the-art adapted equivilization for compensating multipath effects and hitless switching between the redundant equipment, and (3) voice digitizing equipment which multiplexes up to 44 voice channels intermixed with direct digital channels onto a T-1 (1,544 MBPS) Bell Tel. carriers as opposed to conventional PCM digitization of 24 voice channels per T-1 carrier. The digitization also allows virtually error-free transmission of in-band data of up to 4800 BPS. This paper reports on the details of the equipment and the measured performance thereof.
    • Open-Loop Nanosecond-Synchronization for Wideband Satellite Communications

      Holmes, W. Morris; TRW DSSG (International Foundation for Telemetering, 1980-10)
      Successful satellite communication systems, providing service to thousands of users, must feature very inexpensive earth terminals. As many functions as possible must be transferred to the satellite, or a central control station, to reduce terminal complexity and cost. When satellite processors are used to demodulate, route, and error-correction decode and encode the communication channel data synchronization requirements can strongly affect system costs. Time Division Multiple Access (TDMA) is an efficient technique for efficiently distributing satellite services among many system users. Traditional TDMA synchronization techniques feature independent synchronization of each system communication data burst. This is expensive in terms of hardware complexity and system overhead efficiency. Demodulators and data bit-synchronizers must be designed to acquire during short burst preamble times, and unique-word-defectors must be provided to identify the burst time-division-multiplex reference. Burst preambles consume a significant portion of the available communication time, or force long frame periods with expensive buffers, as the number of independent communication channels becomes large. This paper discusses a synchronization technique for use with an onboard processing satellite communication system. The satellite oscillator is used as the system time reference, and as the frequency source for all downlink carriers and data clocks. Downlink timing is established at each system earth terminal by a combination of carrier and dataclock tracking, and a downlink timing epoch signal consisting of one bit per TDMA data burst. Uplink timing is established by an open-loop range prediction process, utilizing precision ephemerides calculated and distributed by the central control station. Overall timing accuracy of the uplink signal at the satellite receiver of ±7 nanoseconds allows unambiguous identification of each data bit position in a 128 Mbps TDMA burst. This is accomplished with simple, inexpensive terminal hardware using available crystal oscillators for time/frequency references and digital synthesis techniques that may be implemented in digital LSI chips. This paper presents terminal hardware block diagrams, satellite block diagrams, and central control station algorithms for the required timing synchronization functions. Error budgets for the identified error sources are also presented.
    • Device Independent Software and Hardware

      Kasser, Joseph; Thorne, Richard; Communications Satellite Corporation (International Foundation for Telemetering, 1980-10)
      The INTELSAT V Communications System Monitoring (CSM) network consists of 11 worldwide installations and a centralized data processing/display facility. Each installation is slightly different from the others due to the local station equipment. The CSM installation consists of a number of control and monitoring equipment interfaced to a HP-1000 minicomputer via the IEEE-488 Bus. This paper describes the modular approach taken in the design of nine pieces of control and monitoring equipment that allowed 27 different units, including differences due to sites and antennas, to be designed within a period of three months. The paper discusses the communications protocols and the device independent software used, to speed the development and debug time.
    • The Large Geostationary Platform and the Real World

      Board, John E.; General Dynamics Convair Division (International Foundation for Telemetering, 1980-10)
      The Space Shuttle will make it possible to place large complicated structures in orbit. The large geostationary platform is a prime candidate for Shuttle launch. A single communications platform placed in geostationary orbit over the United States could alleviate the growing problems of orbit and spectrum congestion by providing communications capacity equal to a large number of conventional satellites at substantially lower cost. A variety of nontechnical and institutional problems such as platform ownership and control, user participation, financial support, and political acceptance must be resolved along with the technical issues of platform/payload design, fabrication, and integration. This paper discusses the institutional aspects of large geostationary platform implementation; presents important economic and political tradeoffs; and identifies potential legal and social problems likely to influence acceptance of the multi-payload, multi-mission concept.
    • Vehicle Telemetry Data in the Vertical Blanking Interval

      Ryan, Thomas J.; BDM Corp. (International Foundation for Telemetering, 1980-10)
      This paper describes how three different developments in digital and video technology have been exploited to provide for the automatic retrieval of data from video tape recordings. By application of the technique of vertical interval data insertion, a pair of 50-bit digital "words" are inserted into two lines of each TV field. The digital words are assembled from a BCD representation of IRIG-B time and both serial and parallel digital data from instrumentation associated with the vehicle. Retrieval of digital time and data annotation from a composite video signal's vertical interval is automatic and yields editing commands and digital data reduction at 3x tape play speeds. This paper defines the functional requirements, describes the implementation concept and provides illustrations of the pragmatic solutions.
    • A Self-Synchronizing Pseudo-Random Bit Error Detector

      Lerma, Jesse; Odetics, Inc. (International Foundation for Telemetering, 1980-10)
      A synchronous pseudo-random bit error detection strategy, incorporating a novel sync acquistion feature, is shown to detect both data and time base errors and to recover sync following such time base errors with no apparent delay, subject to certain error rate constraints. The discussion applies generally to any 2^N-1 pseudo-random sequence. An appendix expands on the linear sequential properties of pseudo-random sequences germain to the implementation of the detection strategy discussed.
    • Laser Communications Acquisition & Tracking Flight Tests

      Abernathy, J. L.; Clark, E. S., III; Dreiseward, D. W.; Maynard, J. A.; McDonnell Douglas Astronautics Company (International Foundation for Telemetering, 1980-10)
      A 1 Gbps laser communications system has been installed in a C-135 aircraft, and acquisition and tracking tests have been successfully completed with a ground station at the White Sands Missile Range. A description of the test site, the installation of the equipment in the aircraft, and the ground test equipment will be discussed. The laser communications system acquisition and tracking will be explained, and system test data presented.
    • Remote Monitoring and Communication of Telemetry Data

      Murphy, Carl G.; Johnson, E. W.; Science Application, Inc. (International Foundation for Telemetering, 1980-10)
      The Brine Measuring System-Environmental Monitoring and Data Acquisition System (BRIMS-EMDAS) being used at the Bryan Mound, Texas, National Strategic Oil Reservoir will be used as an example to demonstrate the system features of a remote monitoring and data communications system. A buoy-mounted telemetry system is used to measure ocean temperature, conductivity and flow required for monitoring salinity levels near pumped brine outputs. The monitoring and communication system described in this presentation provides computer-to-computer communication via network as well as remote user display of data inventory, configuration and engineering unit data. The system stresses ease in configuration and inventory control. Configuration make, change and list functions and inventory list, archive and delete functions are provided.
    • Computer-Aided Analysis of Interference and Intermodulation Distortion in FDMA Data Transmission Systems

      Balaban, P.; Shanmugam, K. S.; Bell Laboratories; University of Kansas (International Foundation for Telemetering, 1980-10)
      Multi-carrier FDMA methods are widely used for transmitting digital data from several sources. In some cases, the digital signals may be controlled by a single clock and hence, the data channels may be fully synchronized. This paper describes a method for evaluating the characteristics of adjacent Channel interference (ACI), and intermodulation (IM) distortion in a FDMA data transmission system with synchronous data streams. A computer simulation method is used to evaluate the statistical characteristics of ACI and IM. It is shown that the IM component is uncorrelated with signal components whether or not the data streams are synchronous. The distribution of the IM amplitude is shown to be Gaussian and hence, the IM can be treated as an additive Gaussian noise component. ACI in multichannel FDMA data transmission systems is also shown to exhibit similar characteristics.
    • The NASA Communications R & D Program

      Durrani, S. H.; NASA Headquarters (International Foundation for Telemetering, 1980-10)
      About two years ago NASA decided to reactivate its communications R&D program, which had been phased down in 1973. The new program focuses on three major areas: technology development in the 30 and 20 GHz bands for wideband communications; system definition for an integrated terrestrial and satellite-aided system for land mobile communications in the 860 MHz band; and development of system concepts and pilot networks for applications data services. The paper summarizes the new activities in the three areas and describes their status and plans.
    • Economics and Key Trades of Fiber Optic Links: An Airborne Platform Example

      Greenwell, Roger D.; Naval Ocean Systems Center (International Foundation for Telemetering, 1980-10)
    • Bit Error Rate Performance of High Density Tape Recorders for Image Processing

      Heffner, Paul; NASA/Goddard Space Flight Center (International Foundation for Telemetering, 1980-10)
      The image processing facility at the NASA/Goddard Space Flight Center utilizes high density tape recorders (HDTR's) to transfer high volume image data and ancillary information from one system to another. For ancillary information it is mandatory that very low bit error rates accompany the transfers. The facility processes approxilately 10¹¹ bits of image data per day from many sesnors, involving 15 independent processing systems that require the use of HDTR's. The original purchase of 16 HDTR's provided 2 x 10⁻⁷ bit error rate as specified. In order to improve the error rate NASA contracted the original supplier of the HDTR's to upgrade the recorders with error correction capability, and successfully achieved the 100 to 1 bit error rate improvement sought by NASA. This paper provides the requirements and conceptual approach to improving HDTR performance and discusses the general technique used to improve the bit error rate. Comparisons are made of actual performance of the HDTR's before and after the modification.
    • Coherent Detection of Frequency-Hopped QPSK and QASK Systems with Tone and Noise Jamming

      Simon, M. K.; Polydoros, A.; Jet Propulsion Laboratory; Axiomatix (International Foundation for Telemetering, 1980-10)
      Perfectly coherent demodulation provides a lower bound on the bit error probability (BEP) of any spread spectrum system. Here the performance of coherent QPSK and QASK systems combined with frequency hopping (FH) or frequency-hopping direct-sequence (FH/PN) spread spectrum techniques in the presence of a multitone or noise jammer is shown. The worst-case jammer and worst-case performance are determined as functions of the signal-to-noise ratio (SNR) and signal-to-jammer power ratio (SJR). Asymptotic results for high SNR show a linear dependence between the jammers' optimal power allocation and the system performance.
    • Configurations for EHF Satellite Communications for Mobile Users

      Chick, R. W.; McElroy, D. R.; M.I.T. Lincoln Laboratory (International Foundation for Telemetering, 1980-10)
      Two-way electronic communications to mobile platforms was initially provided in the HF (3-30 MHz) band. Then, as electronics technology progressed and requirements for increased link availability and capacity emerged, service evolved into the VHF (30-300 MHz), UHF (0.300-3 GHz), and SHF bands (3-30 GHz), with the latter two often involving satellite-based systems. Recently, considerable consideration has been given to utilizing satellite communications systems operating in the allocated EHF (30-300 GHz) bands to provide wide-area coverage, to overcome frequency congestion difficulties, and to provide sufficient bandwidth for projected capacity increases and for interference protection via spread-spectrum modulation techniques. By using emerging spacecraft technologies such as multiple uplink antenna beams, onboard signal processing, and downlink beamhopping, EHF systems can be configured to serve large numbers of small, mobile users. The resulting satellites would be of modest-size, and the associated limited-size user terminals would be less expensive and easier to install and maintain than those for EHF systems which only employ conventional technology. This paper describes several system configuration which use one or more of the above technologies, discusses the advantages of each, and indicates possible spacecraft and terminal implementations.
    • Spectrum of the Product Signal of a PN Code and Its Time-Shared Early and Late Dithering Replica

      Woo, K. T.; TRW Defense and Space Systems Group (International Foundation for Telemetering, 1980-10)
      The spectrum of the product signal of a PN code and its replica offset in time has been analyzed by Gill in [1]. In this paper a more generalized result is obtained. In particular, the spectrum of the product signal of a PN code and its time-shared early and late replica is given as a function of the dithering rate, the magnitude of the dithers (i.e., tau), the code sync error, and the gating function which controls the manner in which time sharing of early and late dithering is accomplished. From this evaluation the effect of PN self-noise on the performance of a direct sequence spread spectrum communication system with taudither code tracking can be quantified.
    • Telematics and Satellites

      Hannell, Sigmund; European Space Agency (International Foundation for Telemetering, 1980-10)
      Today's European Data Communications Networks, independent of whether the network is packet or circuit switched, are mainly designed to serve interactive terminal generated operations at information rates compatible with voice grade channels. The satellite link on the other hand, possesses some unique but versatile properties when used as a data communication medium. In fact, the satellite link in conjunction with modest sized Earth stations located close to, or on the premises of the users would provide a desirable complement to European Data Communications facilities adding, among others, high speed and multidestination capabilities to the existing data networks. The capability to transfer computer files and record messages containing large volumes of binary information, via fast and efficient satellite links enables a range of new applications for telematics systems to be realized. For example, electronic mail types of systems requiring the fast transfer of digital document records would benefit especially from the capabilities of the satellite link.
    • Advanced Medium Scale Real-Time System

      Tucker, Tommy N.; Kelley, Arthur L.; U.S. Army; Sangamo-Weston (International Foundation for Telemetering, 1980-10)
      The requirement for real-time decisions during flight testing of Helicopters at Edwards AFB, and remote test sites has placed a tremendous burden on the telemetry processing system. The Telemetry Processor not only has to have sufficient computer power to give real-time data read outs for the test conductor to make these decisions, but also must be portable to support remote sites. This type of support normally requires two distinctly different systems. The one system for remote support would be a small computer controlled system that digitizes the data, formats all data to digital tape, and gives some limited quick look capability. The data processor would be a large batch processor centrally located in a laboratory, where the digital tapes are returned and the data processed into a meaningful format for the Test Conductor. This does not allow for very many real-time decisions at remote sites, while tests are being conducted. This paper describes the Real-Time Data Acquisition and Processing System (RDAPS) which EMR is delivering to the Army for quick look and processing of the data at remote sites. This is a computer controlled Telemetry System that is portable, while having sufficient power to convert all data (up to 50K word rate) to engineering units, and process and display on CRT's and in graphic form selected parameters that are essential for inflight decisions. This same system will be used to process all of the data between maneuvers and after a flight. Two identical systems support two tests simultaneously.
    • International Telemetering Conference Proceedings, Volume 16 (1980)

      International Foundation for Telemetering, 1980-10