• EARTH STATION IMPLEMENTATION IN THE CANADIAN DOMESTIC SATELLITE SYSTEM

      Winter, A.E.; Nicholson, C.C.; Telesat Canada (International Foundation for Telemetering, 1981-10)
      The domestic communications satellite system operated by Telesat Canada has expanded significantly since its inception in 1973, when, using the Anik A series of satellites in the 6/4 GHz bands, 34 stations commenced service. Since that time, Telesat Canada has implemented many earth stations operating in the 6/4 GHz and 14/12 GHz bands. The paper reviews the design and performance features of the earth stations which provide the wide variety of Telesat services, from “Thin Route” stations used in the Canadian North to the “Network Television” stations used in more southern locations. As an example, the 14/12 GHz heavy-route stations, providing long-haul digital and video uplinks between major city downtown locations, are described in more detail. In conclusion, a summary of new directions in satellite earth station design is presented, including single-circuit transportable earth stations for exploration companies and light-route TDMA earth stations for advanced business networks.
    • EFFECTS OF SOLAR CELL IMPROVEMENTS ON SATELLITE DESIGN

      Wolff, George; Ellion, M. Edmund; Hughes Aircraft Company (International Foundation for Telemetering, 1981-10)
      Recent advancements in gallium arsenide (GaAs) solar cell technology have resulted in appreciable improvements in solar panel performance. The effects of these improvements on weight, size, and power are discussed for three typical satellites: a spin stabilized satellite with rigid drum panels, a 3-axis stabilized satellite with rigid fold-out arrays, and a 3-axis satellite with flexible roll-out arrays. The satellites chosen for these examples are the Hughes HS 376 series standard commercial spin-stabilized satellite, the NASA Solar Max Mission Satellite, and the NASA Large Space Telescope Satellite. The discussion also includes the effects of radiation at synchronous orbits compared to low earth orbits and the effects of temperature on the performance of the solar panel. Typical advantages of a GaAs solar cell spinning array having a beginning of life (BOL) 1 kW power level, in synchronous orbit, over the most efficient silicon solar panels are a reduction of 27 percent in area and a reduction of 7 percent in weight. The improvements are even more dramatic for higher temperatures as will be discussed in the text of this paper. These GaAs solar cells are expected to be available in production quantities by 1985 at a price close to that of silicon cells.
    • END COUPLED PARASITIC MICROSTRIP ANTENNA

      KALOI, MO; PACIFIC MISSILE TEST CENTER (International Foundation for Telemetering, 1981-10)
      A Parasitic Microstrip Antenna Array is discussed. The array consists of different lengths of microstrip radiating elements spaced apart in an end-to-end arrangement. Only one element is actively fed at its feedpoint, and energy emanating from the fed element is primarily coupled to parasitic elements by the electric field generated in the fed element. The radiating pattern is determined by the phase relationship and amplitude distribution between the excited fed element and the parasitic elements. This antenna configuration exhibits higher end fire gain along the missile axis than obtained with arrays having elements individually fed.
    • ENHANCEMENT OF ENDURABILITY BY MODERN TECHNOLOGY IN TRANSPORTABLE MILITARY TT&C GROUND TERMINALS

      Cuccia, C. Louis; Winslow, Roger G.; Ford Aerospace & Communications Corporation (International Foundation for Telemetering, 1981-10)
    • EVOLUTION OF TELEMETRY AND COMMAND SYSTEMS FROM EARLY BIRD TO INTELSAT V

      Magnusson, S. Erland; International Telecommunications Satellite Organization (International Foundation for Telemetering, 1981-10)
      The telemetry and command system on INTELSAT satellites has gone through an evolution from the early series of satellites where simplicity and satellite reliability was emphasized to the latest series of satellites where communications systems reliability is emphasized. The early telemetry and command systems were integrated with the communications subsystem on the satellite and had some redundancy. Later systems are autonomous with complete redundancy and cross-strapping between the systems to a large extent.
    • EXPERIMENTAL COMPARISON OF PCM/FM, PCM/PM and PSK

      Law, Eugene L.; Pacific Missile Test Center (International Foundation for Telemetering, 1981-10)
      This paper compares the experimental bit error rate (BER) performance of PCM/FM, PCM/PM, and PSK. The data are presented as BERs versus signal-to-noise ratio (SNR) in a bandwidth equal to the bit rate. The effects of premodulation filtering and receiver IF bandwidth are discussed. The necessary RF bandwidths for these modulation methods are also discussed. Two methods of generating PSK signals were used: ±90E linear phase modulation and mulitplication of the RF carrier by ±1 using a double balanced mixer. The first method will be referred to as PCM/PM (±90E) in this paper.
    • EXPLOITING TELEMETRY DATA IN THE VERTICAL BLANKING INTERVAL

      Ryan, Thomas J.; Bechtel National, Inc. (International Foundation for Telemetering, 1981-10)
      This paper describes how ongoing developments in digital and video technology have been merged to exploit the telemetry data inserted into the vertical blanking interval of the composite-video signal. The insertion of 96 bits of digital data into two lines of the vertical blanking interval is reviewed. The automatic retrieval and reformatting of the digital data for use by a Main-Frame Computer is explored. A unique video editing and data merging facility coupled to the computer is described. To emphasize the versatility of this systems approach, specific industrial applications will be outlined. Finally, future considerations and applications involving control systems will be discussed.
    • THE FEDERAL DATA ENCRYPTION STANDARD IN THE 1980’S

      Burris, Harrison R.; NOETECHNIC INDUSTRIES INC. (International Foundation for Telemetering, 1981-10)
      The development of the federal data encryption standard is traced from the requirements leading to inception of the project through the publication of federal and commercial (ANSI) standards. The algorithm is briefly reviewed and strengths and weaknesses are discussed. Current applications are described and some potential developments are presented.
    • FREQUENCY HOPPING SYNTHESIZERS EMPLOYING CONVENTIONAL, COMMERCIALLY-AVAILABLE INTEGRATED CIRCUITS

      Dixon, R. C.; R & D Associates (International Foundation for Telemetering, 1981-10)
      A number of integrated circuit frequency synthesizers are available for use in commercially-oriented radio receivers and transmitters. Application of these for frequency hopping systems is extremely attractive, but little information exists as to their capability for such use. This paper examines the switching speed, frequency range, and flexibility of currently available I. C.’s, and gives both experimental and calculated results.
    • FREQUENCY SELECTIVE SURFACES FOR SPACEBORNE MISSIONS

      Herndon, D.H.; Herschelman, F.Q.; Harris Corporation (International Foundation for Telemetering, 1981-10)
      Periodic arrays of metallic scatters have found widespread application in microwave antennas as frequency selective surfaces. The exact surface reflection and transmission characteristics depend on the length, width, and spacing of the metallic elements, and the dielectric constant and thickness of the supporting structure. The arrays are effectively filters when used in this application, and it would seem more efficient to specify the response with poles. The poles of each array are calculated using the Singularity Expansion Method (SEM). How the poles vary with changing geometrical parameters are calculated and plotted. The currents, and charges induced on the scatterers are treated using Floquet theory which is incorporated in a vector E-field integral equation. The SEM parameters are presented in the form of appropriate graphs and tables. In addition these data are compared with previously obtained data for multiple bodies and in particular with data used in the design of the frequency selective surface for the GALILEO space mission.
    • FUTURE TRANSATLANTIC LIGHTWAVE COMMUNICATION SYSTEMS

      Wagner, Richard E.; Bell Laboratories; Runge, Peter K. (International Foundation for Telemetering, 1981-10)
      Bell Laboratories is actively involved in applied research work on single mode long wavelength technology which might lead to a development program for optical undersea transatlantic communication systems. This talk addresses the economic justification for optical transatlantic systems, and describes projected system parameters for a first system targeted for service in the year 1988. The current state of technology of major system elements is described, and projections are made for future generation optical undersea systems.
    • A GENERAL APPLICATION REAL TIME PROCESSING AND DISPLAY SYSTEM

      Schumacher, G. A.; Sangamo Weston, Inc.-Data Systems Division (International Foundation for Telemetering, 1981-10)
      A general purpose system for the processing and display of telemetry data is described. The system uses a DEC PDP-11 mini-computer as the system processor. Systems of this type implemented in the past generally had limited data processing capabilities due to high data rates and limited CPU power. The Real Time Data Monitor System (RTDMS) is designed to maximize the data processing capability by teaming the CPU with a pre-processor. A total hardware/ software system was designed which is structured around certain commonly required classes of data. The system minimizes the processor overhead associated with each class thereby freeing time for useful processing. A complete software system was implemented which takes full advantage of the RSX-11M multi-task operating system. Because of the substantial data base required to configure the system, particular attention was given to the operator interface. A set of programs were implemented which construct all data base files required using interactive menus. Operator input is minimized as well as the training time required to set-up the system.
    • GEOSTATIONARY OPERATIONAL ENVIRONMENTAL SATELLITE (GOES)

      Nakamura, Apryll M.; Mallette, Leo A.; Hughes Aircraft Company (International Foundation for Telemetering, 1981-10)
      The GOES satellites are multifunctional satellites whose primary function is to provide continuous measurements of the earth’s surface and atmosphere from two geostationary orbit locations: 75°W and 135°W. This objective is accomplished with the Visible infrared spin scan radiometer Atmospheric Sounder (VAS). The atmospheric sounder is a new feature which will add a third dimension to the photographs of the earth seen nightly by TV newscast viewers. The satellite also contains a Space Environment Monitor (SEM) which includes three instruments: a magnetometer, a solar X-ray sensor and an energetic particle sensor (EPS), which monitor solar flares and near earth space environment. The satellite contains a communications system which, in addition to transmitting VAS, SEM and housekeeping data to earth, provides relay capabilities for the stretched VAS and weather facsimile (WEFAX) data, as well as for the Data Collection Platform (DCP). A sketch of the satellite is given in Figure 1. The telemetry system encompasses two subsystems: RF communications and baseband assemblies. A general diagram of the telemetry system is shown in Figure 2. The telemetry system consists of two functional operations; real time telemetry data which is frequency modulated into IRIG 12 and IRIG B, and PCM data which is phase modulated. The baseband assemblies collect, format and modulate the data. The RF system sums the PCM and IRIG signals, phase modulates it onto both the CDA and STDN carriers, and transmits it to the ground stations. The following sections will describe in further detail the operation of the PCM and real time telemetry functions, and a description of the satellite RF communications system.
    • GOES COMMUNICATIONS SYSTEM

      Fermelia, L. R.; Hughes Aircraft Company (International Foundation for Telemetering, 1981-10)
    • 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.