• HARDWARE/SOFTWARE ARCHITECTURE FOR A MICROPROCESSOR AIRBORNE TELEMETRY ENCODER

      Kellom, Arthur W.; Sandia National Laboratories (International Foundation for Telemetering, 1981-10)
      Successful programming of a microprocessor for airborne telemetry requires attention to proven programming techniques, as well as consideration of additional constraints that are required by the hardware involved. This paper describes a custom microprocessorcontrolled telemetry encoder developed by Sandia National Laboratories. The telemetry is used to encode and transmit data from warhead development and quality assurance tests. This paper briefly describes the encoder, discusses in some detail the structure of the software, and concludes with a mention of future telemetry development planned. The general principles of encoding are emphasized rather than an extensive discussion of software used in this system.
    • A HIGH RESOLUTION MBA FOR EHF COMMUNICATION SATELLITES

      Cummings, William C.; Ricardi, Leon J.; Schwab, Leonard M.; Massachusetts Institute of Technology (International Foundation for Telemetering, 1981-10)
      Communication satellites currently operate at frequencies lower than 15 GHz. Future satellite communication systems will operate in the EHF band between 17 and 47 GHz, in order to realize increased bandwidth and antenna discrimination. Increased discrimination can be obtained with electrically large aperture antennas consisting of filled, or thinned arrays, or a multiple-beam antenna (MBA) using millimeter-wave optics. This paper describes a contemporary MBA and beam-switching network system capable of achieving high resolution and significant operational flexibility. The antenna can simultaneously provide narrow beams and medium-size beams directed to any point on the earth’s disc as seen from a geosynchronous satellite.
    • A HIGH-PERFORMANCE ERROR CORRECTION SYSTEM FOR DIGITAL TAPE RECORDERS

      Kessler, W.D.; Stein, J.H.; Sangamo Weston, Inc. (International Foundation for Telemetering, 1981-10)
      An erasure type error correction system for parallel high density digital tape recorders is described. The system can correct for error bursts of any length occuring on either single tracks or any two tracks simultaneously. Calculations of theoretical performance are compared with measured performance and a figure of merit for error correction systems is used to compare typical systems.
    • HOW SMALL CAN AN ELECTRO-OPTICAL TRANSOCEANIC CABLE BE?

      Wilkins, George A.; Naval Ocean Systems Center Hawaii Laboratory (International Foundation for Telemetering, 1981-10)
      Design theory and analyses are presented for a transoceanic, electro-optical ( E-O), telemetry cable which---because its data, power and tensile functions can be separately optimized---has a very small diameter and transport volume. These reductions are achieved with no compromises of operational or material constraints on the telemetry system. For example, an ocean E-O cable which can directly support repeatered, multi-fiber telemetry between Japan and the United States will have a diameter less than 0.75 cm. Its transport volume will be barely 5% of that required for the smallest coaxial cable (SD List 1 with a 3.18-cm diameter) now being used in transoceanic communications. A cable design is demonstrated for a set of system parameters which define a 5550-kmlong “baseline” communications system. The study evaluates that system’s sensitivity to changes in such system parameters as length, repeater power and separation, water depth and safety factor, cable specific gravity, dielectric voltage stress, conductor conductivity, and the failure- or yield strains of loadbearing components. It is concluded that the cable should be relatively inexpensive. Its design can be tailored for specific applications with little change in manufacturing complexity or cost. The cost and risk of ocean deployment should be considerably reduced, since small ships can be loaded with ocean-crossing lengths of this miniature E-O cable.
    • HOW THE 1980’s LOOK FOR GODDARD SPACE FLIGHT CENTER’S SPACEFLIGHT TRACKING & DATA NETWORK

      SMOR, PAUL R. (International Foundation for Telemetering, 1981-10)
      The Spaceflight Tracking and Data Network (STDN), operated by NASA’s Goddard Space Flight Center, finds itself adapting to internal and external changes. Among these changes, now familiar to all of us, are higher data rates, shrinking budgets, and to some extent this nation’s relations with foreign governments. This paper strobes the STDN in a period of rapid evolution. This evolution embraces automation, consolidation, and the development of a space borne data relay network to replace terrestial stations. The STDN is only one of several worldwide data and communications networks. Perhaps others will tread similar paths.
    • HUMAN FACTORS IN TELEMETRY SYSTEM DEVELOPMENT

      Chafin, Roy L.; Jet Propulsion Laboratory (International Foundation for Telemetering, 1981-10)
      Telemetry systems are becoming increasingly sophisticated and complex. At the same time, economics is forcing the use of fewer and less technically skilled operators. This paper suggests including human factors in systems design to better match system characteristics with operator characteristics. It discusses why human factors should be included in system design. It defines and discusses human factors. Human factors specialists are the practitioners of the art and science of human factors design. The art is in the experience and insight of the human factors specialists, and the science is in his knowledge of the theoretical foundations of human factors. His knowledge and experience is applied to telemetry system design at several places in the design effort. Early in the requirements phase, human factors specialists identify the human factors issues and establish man-machine interaction philosophy and human factors design guidelines. During the design phase they assist the designers on the detailed design of the man-machine interface. After and even during the design phase, the human factors specialists evaluate the design with theoretical analysis. After delivery, they evaluate the system in its operating environment using real operators.
    • IMAGING TERMINAL GUIDANCE SEEKER

      Mohanty, N. C.; The Aerospace Corporation (International Foundation for Telemetering, 1981-10)
      A certain guidance seeker is designed to aim at the location of the most vulnerable point of a moving target. The seeker extracts an appropriate feature of the target and continuously tracks it using a tracking algorithm. The performance of the tracker was evaluated in terms of probability of acquisition and positional error. The algorithm was verified using a data base obtained from the flight of an A-7E aircraft. The cockpit of the aircraft was continuously identified by a rectangular gate as the seeker’s aimpoint.
    • IMPACT OF LSI ON CRYPTOGRAPHY

      Cohen, Ken; Western Digital Corporation (International Foundation for Telemetering, 1981-10)
      The existence of a cryptographic algorithm in LSU gives the system designer real choices for integrating cryptography into a product. This paper will explore some of the trade-offs in providing data communication security at different levels of the ISO model and their impact on security and the ability to communicate.
    • IMPACT OF MOLECULAR BEAM EPITAXY TECHNOLOGY ON SPREAD SPECTRUM SYSTEMS

      O’Clock, George D.; Erickson, L. Peter; Physical Electronics Division (International Foundation for Telemetering, 1981-10)
      The ultimate limitations in system performance capabilities are often due to constraints imposed by various device or chip fabrication processes. Recent advances in semiconductor processing technology have helped to lift some of the device performance barriers that have a negative impact on system performance. Molecular Beam Epitaxy is one particular technique that has the capability to fabricate a wide range of high performance semiconductor devices with high levels of reliability and yield. Molecular Beam Epitaxy (MBE) is an ultrahigh vacuum evaporation process for growing epitaxial films on various substrate materials. The basic constituents of the films are thermally evaporated and directed toward a heated substrate. The evaporated materials are deposited on the heated substrate surface forming a film. MBE offers the ability to maintain a higher level of precise control over material composition and film thickness required for semiconductor devices utilized in microwave and millimeter wave spread spectrum system applications.
    • THE IMPACT OF THE IEEE-488 CONCEPT ON MEASUREMENT PRODUCTIVITY

      Stanley, George C.; Hewlett-Packard Company (International Foundation for Telemetering, 1981-10)
      In the mid 1970’s three events came together that have had a major impact on measurement productivity. The most significant of these was the IEEE-488 Interface Bus. The second was the “friendly”, interpretive-language desktop computer and the third was the intelligent or “smart” instrument. Since the combined impact of these three has been enormous, their-development and relationships will be briefly traced. Next covered will be the technical characteristics of the interface bus with emphasis on what sets the technical limits of speed, distance, and number of products connected. Knowing this leads to a discussion of how to go beyond these limits if required. Finally, this paper examines the application of these concepts using two aerospace examples and describes the resultant productivity improvements.
    • THE INFLUENCE OF ARM FILTER DELAY ON TRACKING PERFORMANCE OF A COSTAS LOOP

      Holmes, Jack K.; Holmes Assoc. Inc. (International Foundation for Telemetering, 1981-10)
      It is demonstrated that the effect of the arm filters with NRZ data in a second-order Costas loop is to introduce delay in the loop which causes the tracking-error jitter to increase. It is shown that the tracking-error jitter becomes unbounded at exactly the same value of delay as the loop becomes unstable. The results are derived for both the one pole passive and the Integrate and Dump arm filter cases. A representative calculation shows that this is normally not a significant problem in properly designed loops.
    • INFORMATION RATES IN FIBEROPTIC LINKS WITH MULTI-LEVEL PULSE INTENSITY ENCODING (MPIM)

      Sorensen, A. N.; Gagliardi, R. M.; The Aerospace Corporation; University of Southern California (International Foundation for Telemetering, 1981-10)
    • Infrared telemetry range for fire management

      Warren, John R.; USDA Forest Service (International Foundation for Telemetering, 1981-10)
      The USDA Forest Service has used airborne infrared systems for forest fire detection and mapping for many years. The transfer of the images from plane to ground and the transposition of fire spots and perimeters to maps has been performed manually. A new system has been developed which uses digital image processing, transmission, and storage. Interactive graphics, high resolution color display, calculations, and computer model compatibility are featured in the system. Images are acquired by an IR line scanner and converted to 1024 x 1024 x 8 bit frames for transmission to the ground at a 1.544 M bit rate over a 14.7 GHZ carrier. Individual frames are received and stored, then transferred to a solid state memory to refresh the display at a conventional 30 frames per second rate. Line length and area calculations, false color assignment, X-Y scaling, and image enhancement are available. Fire spread can be calculated for display and fire perimeters plotted on maps. The performance requirements, basic system, and image processing will be described.
    • AN INSIDE VIEW OF PSEUDORANGE AND DELTA PSEUDORANGE MEASUREMENTS IN A DIGITAL NAVSTAR GPS RECEIVER

      Painter, John; Noe, Phil; Rhyne, Tom; Department of Electrical Engineering (International Foundation for Telemetering, 1981-10)
      Marine C/A GPS receiver position data has been collected for about two years by the USCG and TAMU researchers aboard the R/V Gyre. Recent studies show results obtained with USGS personnel from Woods Hole. The USGS personnel were onboard the Gyre for a short cruise from Tampa, Florida to Maine investigating LORAN C properties and accuracies in comparison with GPS and Transit. These studies were made to identify cause of large biases previously reported between LORAN C and GPS in the first phase of the TAMU/USCG research effort. Equipments used in this test were a Magnavox GPS Z-set, Internav 404 LORAN C, Tracor Omega, and Magnavox Transit receivers.
    • AN INSIDE VIEW OF PSEUDORANGE AND DELTA PSEUDORANGE MEASUREMENTS IN A DIGITAL NAVSTAR GPS RECEIVER

      Ward, Phil; Texas Instruments Incorporated (International Foundation for Telemetering, 1981-10)
      The goal of this paper is to develop insight into the real-time nature of GPS observables measured by a digital receiver. The concept of how independent pseudorange and deltapseudorange measurements are captured as a by-product of the code and carrier tracking loops of a digital NAVSTAR GPS receiver is explained. The classical equations defining true range and delta range are derived in terms of pseudorange and delta pseudorange. The actual GPS receiver measurements are then related to these equations. The difference between GPS measurement resolution and precision is treated and the sources of the GPS receiver contribution to the total GPS error are identified. The total GPS error, in terms of user equivalent range error (UERE) and user equivalent delta range error (UEDRE), is characterized. However, an unaided GPS navigation process can filter out only the unbiased random error in the observables, not the total UERE and UEDRE content. Also, the random error in GPS observables is not stationary. Hence, the random error in UERE and UEDRE is identified and characterized.
    • INSTANTANEOUS FIBER OPTIC VISICORDING OF HIGH INTEREST/HIGH FREQUENCY DATA

      Calandrino, Peter; Calandrino Electronic Systems (International Foundation for Telemetering, 1981-10)
      The ability to display, expand, time frame select, and permanently record data of high interest/high frequency over long time periods provides the capability to analyze data in near real time and provide immediate responses to laboratory or remote platform/onboard system problems. Many recording techniques provide large recording bandwidths, but do not also provide an immediate hard copy readout from which early decisions can be made. A wider bandwidth capability can expand the already large spectrum of visicorder uses. This paper describes a new high speed recording capability which involves the introduction of an x/y converter/fiber-optic visicorder system into a telemetering link that can record one MHz data for long periods of time, together with time frame selection capability. The system can provide line continuous monitoring of high interest data.
    • INTELSAT V SPACECRAFT TELEMETRY COMMAND AND RANGING

      Johnson, Charles E.; Communications Satellite Corporation Palo Alto (International Foundation for Telemetering, 1981-10)
      The INTELSAT V communications satellite was designed and assembled by the Ford Aerospace and Communications Corporation of Palo Alto, California, for the International Telecommunications Satellite Consortium (INTELSAT). The Communications Satellite Corporation (COMSAT) is the designated United States representative to INTELSAT and also performs technical service for INTELSAT in monitoring the design, fabrication, and test of communications satellites. The TT&C subsystem consists of two functionally redundant and independent command and telemetry channels, the major elements of which are shown in Figure 1. The telemetry subsystem provides two data channels for formatting and transmitting data received from sensors, transducers, and status indicators in the various subsystems of the spacecraft. In addition, the output of a command receiver can be connected to a telemetry transmitter to form a ranging transponder. The telemetry unit can provide normal or dwell PCM data in NRZ-M format modulated on a 32 KHz subcarrier. The telemetry transmitter phase modulates one of the data subcarriers or ranging tones on a 4 GHz band downlink carrier. The transmitter output is routed directly to an earth coverage conical horn for transmission at a level of approximately 0.0dbW. The transmitter output can also be routed through a zone communications channel TWTA to a telemetry omni-directional bicone antenna for extended coverage. Commands and ranging tones are received on a 6 GHz band uplink carrier through dual Omni pattern antennas. The received signal is routed through a passive filter to the two command receivers where the frequency modulated command or ranging tones are detected. The command tones are routed to the command units for processing. The command transmission is either a command message, consisting of 58 serial bit, or a command execute. The command message includes the address of the command unit which is to be used and what specific command function is to be executed. The command units provide the capability for pulse, discrete relay, and proportional relay command functions required by the various subsystems of the spacecraft.
    • International Telemetering Conference Proceedings, Volume 17 (1981)

      International Foundation for Telemetering, 1981-10
    • ISPM SPACECRAFT ANTENNAS

      Wong, Gary G.; TRW Defense and Space Systems Group One Space Park (International Foundation for Telemetering, 1981-10)
      International Solar Polar Mission (ISPM) is a dual-spacecraft mission sponsored jointly by NASA and European Space Agency (ESA) to gather scientific information for further understanding of the sun and predicting its influence on the Earth’s weather and climate. Jet Propulsion Laboratory of the California Institute of Technology has selected TRW to buiId U.S. spacecraft for the joint mission. The dual spacecraft will fly to Jupiter and use that planet’s greater gravitational field to achieve a near 90 degree orbit change, placing the two spacecraft on separate trajectories to the North and South poles of the Sun from a high heliographic vantage point. The antenna subsystem of the ISPM spacecraft consists of S-/X band high gain, S-band broad coverage, and X-Band medium gain antenna. Command and ranging signals are received by the S-band high-gain and broad-coverage antennas. Scientific and engineering data are transmitted by these two antennas and the X-band high-gain antenna. Conscan acquisition is by the two S-band antennas. Emergency transmissions are by the S-band broad coverage and X-band medium-gain antennas. The S-/X-band HGA is a 1.9 meter (78 inches) diameter dual reflector Cassegrain design with a dichroic subreflector. The Cassegrain mode is excited by an efficient dual mode conical horn whose dimensions have been optimized to provide high-gain performance for X-Band. The S-band feed, located directly behind the frequency selective subreflector, illuminates the parabolic reflector as a focal point feed, laterally displaced by 2.29 cm (0.9 inch) to provide conscan signals with a 1 dB crossover level. The selected configuration permits the use of a common antenna for both X- and S-band functions and utilizes previously developed TRW hardware. The selected design represents the largest non-deployable antenna that could be accommodated by shuttle/IUS and spacecraft physical interfaces. An x-ray XUV telescope (CXX) is located on the center of the spacecraf t which is despun about the spacecraft +Z axis. The ends of the coronograph cast shadows onto the edge of the reflector up to 9.72 cm (3.83 inches) inside the reflector. The shadowing effects from the coronograph have been analyzed and subsequently verified by antenna range testing. The performance of each antenna is substantiated by analyses and test data and pertinent design and analysis results are presented.
    • LINE OF SIGHT COMMUNICATIONS TRENDS

      Sauer, Wes; Naval Ocean Systems Center (International Foundation for Telemetering, 1981-10)
      This paper briefly reviews some of the historical trends in LOS communications along with a synopsis of some of the characteristics associated with LOS systems. The Joint Tactical Information Distribution System (JTIDS) is briefly described as one example of current developments aimed at satisfying a number of requirements such as jam resistance, security, and error-free transmission. A brief review of the problems in various applications of LOS systems concludes the paper.