• CIVIL APPLICATION OF DIFFERENTIAL GPS

      Cardall, John D.; Cnossen, Richard S.; Magnavox Advanced Products and Systems Company (International Foundation for Telemetering, 1981-10)
      GPS has the potential of satisfying worldwide and local civil navigation requirements for Area Navigation (RNAV), Landings and Takeoffs under minimum ceilings and Advanced Air Traffic Control (ATC) Operations. Use of GPS in a differential mode in local areas is a key to achievement of this potential. This report describes the GPS system and its status; discusses GPS signal availability for the civil community; defines alternative differential GPS concepts; shows predicted performance enhancement achievable with differential GPS and the operational improvements which are expected.
    • COLOCATED COMSTARS

      Lee, David J.; Guthrie, W. Coleman; McKee, Walter S., Jr.; COMSAT General Corporation (International Foundation for Telemetering, 1981-10)
      Both AT&T and GSAT are presently using the COMSTAR to expand and diversify their domestic public dial telephone networks. COMSAT General’s TTC&M earth station facilities at Southbury, Connecticut, and Santa Paula California, continuously monitor the status of the COMSTARs. For the purpose of increasing the likelihood of availability and maximizing the number of communications transponders to the users, at the end of the spacecraft design lifetime, COMSAT General was able to reach a business agreement with AT&T and obtain FCC authorization to launch COMSTAR D-4 and colocate D-1 and D-2. Therefore, as far as the communications earth stations are concerned, colocated D-1 and D-2 with a coordinated 24 TWT configuration are technically identical to a single COMSTAR satellite. There is, however, a significant increase in satellite lifetime due to reduced solar array and battery loading (about half) since each satellite now operates with twelve TWTs on instead of the usual twenty-four for a COMSTAR. This paper will describe the TTC&M earth stations’ modification to accommodate the colocated satellites. Operational considerations and some actual operational experience will also be discussed.
    • COLOR ENHANCEMENT OF TELEMETRY DISPLAYS

      Tremain, George F.; Layton, Jerry; Decom Systems, Inc. (International Foundation for Telemetering, 1981-10)
      This paper will describe the enhancement to the man-machine interface brought about by the use of color CRT’s in a real time, de-centralized telemetry processing system. The use of a microprocessor controlled telemetry system allows equipment set-up and various data outputs displayed using an off the shelf intelligent color terminal. The use of color annotated messages and graphics allows a more effective interaction between the operator and the system.
    • COMMUNICATIONS FOR THE ESA GIOTTO (COMET HALLEY ENCOUNTER) MISSION

      Wasse, Michael P.; European space Technology Centre (International Foundation for Telemetering, 1981-10)
      This space mission will investigate the structure of the comet by passing close to the nucleus. The spacecraft will first be injected into a geostationary transfer orbit where a perigee boost motor will deliver the kick necessary to encounter the comet post perihelion, as it passes through the ecliptic plane at a distance of 0.98 AU from the earth. The spinning spacecraft and the use of a shield for protection from the dust present in the comet atmosphere dictate the use of a despun high gain antenna with inclined beam. The telemetry downlink at 40 KBps is in X Band and will be received on the Parkes (Australia) radio telescope which will be specially adapted for the task. The trade offs leading to the selected communications configuration are described along with the various spacecraft hardware items such as antennas, transponder, decoder and twta.
    • COMMUNICATIONS NETWORKING FOR MILITARY APPLICATIONS

      Carpenter, W. D.; Naval Ocean Systems Center (International Foundation for Telemetering, 1981-10)
    • COMMUNICATIONS SATELLITE CONFIGURATIONS FOR THE 1990’s

      Pentlicki, Chester J.; Esch, Fred H.; COMSAT Laboratories (International Foundation for Telemetering, 1981-10)
      Continuing growth in domestic and international communications traffic indicates a need for expanded communications satellite capacity. The size of spacecraft for the 1980’s has been established and design concepts to meet the increased capacity of the 1990’s are under consideration. Launch vehicle capability permits alternatives to single-purpose spacecraft for the new era. Multipurpose spacecraft platforms and clustered satellites are concepts with unique advantages. Platform concepts will be seen in the 1990’s, and growth in technology will permit dedicated spacecraft to achieve new levels of capacity. Technical advances in the 1990’s will include extended spacecraft lifetime possibly enhanced by refurbishment of payloads. Technical capability may well exceed the ability of institutions to utilize it, and innovative arrangements, including participation of financial institutions, may be required to fully exploit the improved technology. In this paper, influential factors, such as multiple narrow-beam antennas coupled with precise pointing, are appraised in terms of design consequences and their impact on spacecraft subsystems is identified.
    • A COMPUTER-AIDED SIMULATION PROGRAM DESIGN FOR TESTING THE FLIGHT CONTROLLER OF A THREE AXIS STABILIZED SPACECRAFT

      Basuthakur, Sibnath; General Electric Company (International Foundation for Telemetering, 1981-10)
      To insure a reliable performance of any spacecraft over its long mission life, a thorough and coordinated attitude control subsystem testing must be conducted. The three axis motion Simulator-Hybrid computer facility at General Electric has provided the capability of testing the Attitude Control Electronics (ACE) for various satellite programs including Japanese satellite program BSE and Defense Communication Satellite DSCS-III. Although the facility has provided complete verification of analysis and simulation of all operating modes in a closed-loop fashion, the checkout procedure has proven to be extremely timeconsuming. It requires real time dedicated computer support. In addition, limited sensor field of view may, in some instances, limit the scope of the test. The objective of this paper is to underline an alternate philosophy of the subsystem testing that has been extensively used to qualify the DSCS-III flight control system under various environments. It is designed to compare, on a bit by bit basis, all critical controller internal and output parameters between the flight control algorithms embedded in the ACE and a validated simulator controller. The simulated controller (truth model) is validated after careful analyses and simulation of all operating modes under all possible initial conditions. All controller parameters to be compared are assigned to CPU test port and the telemetry port. This computer-aided testing program is used to process CPU output data in an off-line autonomous basis to validate the control algorithms embedded in the ACE.
    • CONSOLIDATED SPACE OPERATIONS CENTER

      Thibodeau, Lionel; Lt. Col. Fornwalt, Harry C.; The Aerospace Corporation; USAF Systems Command (International Foundation for Telemetering, 1981-10)
      The Consolidated Space Operations Center (CSOC) is being designed by the Air Force Systems Command Space Division to centralize all Department of Defense Space Shuttle and satellite operations within a single secure facility. CSOC will be located near Colorado Springs, Colorado. It will provide DOD with enhanced space command and control capabilities in the late 1980s and 1990s. It will include a Satellite Operations Complex (SOC), a Shuttle Operations and Planning Complex (SOPC), and communications, facilities, and support segments. An initial operational capability is planned for mid-1986 that will include appropriately selected portions of SOC, SOPC, and the integrated segments. These early limited capabilities will be expanded in the late 1980s to satisfy the requirements of the DOD mission model. SOC will share command and control of space satellite missions with the Satellite Test Center (STC) in Sunnyvale, California. The STC is part of the Air Force Satellite Control Facility (AFSCF). Both the STC and SOC will control assigned satellite missions using the AFSCF remote tracking stations located at seven sites around the world. SOC will be functionally equivalent to a portion of the STC as improved by the data systems modernization program. SOC and STC will be interoperable to permit mutual backup in the event of an extended failure at either center. SOPC will be functionally equivalent to portions of the Shuttle operations complex at the NASA Johnson Space Center (JSC). It will provide for flight planning, flight readiness, and flight control of DOD Shuttle flights. As with SOC and STC, SOPC and JSC flight control facilities will be able to provide critical backup support to each other in the event of an extended failure at either center. External wideband communications circuits at CSOC will interface with both NASA and Air Force space facilities, such as the eastern and western launch sites, JSC, and the AFSCF remote tracking stations. Satellite relay techniques using both Defense Satellite Communication System (DSCS) satellites and Domestic Communications Satellites (DOMSAT) will be the basic method of network communication. Dedicated narrowband circuits, provided by leased lines accommodating both voice and data, will interface mostly with other Air Force space facilities. This paper discusses the CSOC program background, configuration, operations concept, external interfaces, and acquisition status.
    • CONSOLIDATION AND PLANNED DEVELOPMENT OF THE NASA GROUND TRACKING NETWORKS

      Layland, J. W.; Yeater, M. L.; McClure, D. H.; Jet Propulsion Laboratory (International Foundation for Telemetering, 1981-10)
      The Networks Consolidation Program (NCP) was established by NASA in the fall of 1979 to accomplish the consolidation of the two NASA Ground Tracking Networks into a single unified network. Consolidation of the two networks had been recommended by an all-Networks NASA planning group and presented to NASA top management in October of that year. The consolidated network of 1986 will make use of facilities that are now included in the Goddard Ground Spaceflight Tracking and Data Network as well as the existing JPL Deep Space Network. These facilities will be combined and modified to provide a consolidated network that is capable of supporting the set of planetary and high earth orbiter missions that are planned for that era. The drivers for the development of the consolidated network are both technical and economic. The consolidated network must provide the increased sensitivity needed to support the Voyager 2 spacecraft at its distant encounters with Uranus and Neptune in 1986 and 1989. It must provide support to spacecraft in high earth orbit and at the nearby planets at data rates which may be a factor-of-ten higher than present deep space data rates. And it must do both with significantly less cost for maintenance and operation than the sum of the separate networks would have cost in the late 1980’s. This report traces the history of activities and events that led to the decision to consolidate the NASA ground tracking and data networks. It also presents a summary of the planned evolution of the NASA ground tracking networks, from the time of decision in October 1979 through the mid 1980’s. It is an updated version of a report presented at the AIAA/NASA symposium on Space Tracking and Data Systems, June 1981.
    • DESIGN AND PERFORMANCE OF AN OPTIMAL RATIO COMBINER USING AGC AND AM WEIGHTING

      Lennox, William M.; Microdyne Corporation (International Foundation for Telemetering, 1981-10)
      The conventional AGC weighted diversity combiner design experiences performance problems in the presence of fast fade rates of amplitude and phase of RF input signals. These problems and other needs are discussed by the author in detail along with the design and theory of a new combiner that has been developed. It successfully overcomes these phase and amplitude fading problems and also addresses many other problems such as the need for wider bandwidths, computer control, and many other improvements. These improvements are necessary to increase the state-of-the-art in the telemetry and communications combiner. The design criteria and realization of the design goals are described in detail accompanied by a block diagram discussion of the theory of operation.
    • DESIGN AND PERFORMANCE OF AN UNDERSEA, SINGLE-FIBER MULTI-REPEATER, FULL DUPLEX, ELECTRO-OPTICAL DATA LINK

      Wilkins, G.; Nakagawa, A.; Kamikawa, N.; Baldwin, D.; Couch, P.; Naval Ocean Systems Center Hawaii Laboratory; ITT-EOPD (International Foundation for Telemetering, 1981-10)
      Fiber optics’ major contributions to undersea communications should include greater telemetry bandwidth, improved data precision and a decrease of system volume. The last two of these served as primary goals during recent design, fabrication and ocean testing of an undersea, electro-optical (E-O) telemetry system. The system’s total length was nearly 70 km. It contained 8 in-line repeaters which were powered through the E-O cable. Data were transmitted full duplex (22 MB/s at 0.83 μm & 43 KB/s at 1.06 μm through a single optical fiber. Power consumption was 1.69 watts for each repeater. Telemetry BER through the 70-km cable path was better than 10^-9 at 22 MB/s. The repeater housings were designed for 1-km ocean depths. Their dimensions (including bend-limiting cable terminations) were 2.88-cm diameter by 30.5 cm length. Each repeater contained special circuitry so that it would be queried from shore in a fault diagnosis mode. Designs and performance are reported for the E-O telemetry system and for its major components.
    • DESIGN FEATURES OF A NEW REMOTE CONTROLLED TELEMETRY RECEIVER

      Knowles, Robert C.; Moore, John M.; Woodworth, Donald J.; Magin, Greg A.; Microdyne Corporation (International Foundation for Telemetering, 1981-10)
      This paper describes some design features of a new microprocessor controlled, single channel telemetry receiver which will have use in the automated telemetry systems beginning to emerge. The parameters controlled, and the methods used to interface the receiver with the controller or another slave receiver to create the equivalent of a dual channel remote controlled receiver are discussed. A general description of the software utilized by the receiver is included. A new four bandwidth FM demodulator is described which utilizes modern technology to provide FM demodulation over the full range of receiver IF bandwidths. It features a high gain limiter having excellent output waveform symmetry and a linear phase detector with PIN diode switched linear phase shift networks to realize a demodulator exhibiting excellent linearity. A wide angle PM demodulator is also described which features a novel antisideband circuit utilizing PM feedback to essentially unmodulate the received signal and thereby prevent sideband lock.
    • DEVELOPMENT OF A MILITARY COMMUNICATION SYSTEM: A MULTIPLE RATE PROCESSING APPROACH

      Kline, E. Lee; Naval Research Laboratory (International Foundation for Telemetering, 1981-10)
      This paper represents some considerations resulting from work conducted during a Navy study of secure voice system alternatives and the development of military communication systems. It begins by identifying a set of attributes for a “goal” military communication system. The paper then presents a realizable communication system concept which could be used as a basis for a future system design. The concept is based on an embedded multiple rate system where a basic mode, supported at the lowest transmission rate, is enhanced using additional transmission capacity, when it is available, to support a higher rate. The conclusion discusses the impact of this concept on some of the functions a military communication system must perform.
    • DIDON: DIGITAL DATA IN VIDEO

      BERNHEIM, J.-P.; Communications Enaineer (International Foundation for Telemetering, 1981-10)
    • DIGITAL DATA IN VIDEO PROCESSING SYSTEMS

      Morse, Bob A.; BELL TECHNICIAL OPERATIONS (International Foundation for Telemetering, 1981-10)
      Digital information in video systems is an expanding field. The use of digital video equipment is continuously being examined and updated at USAYPG. There are fully operational systems currently being used by BELL TECH. OPS at the proving ground. I shall cover some of the uses and capability of the systems as well as the individual pieces of equipment in the systems
    • DISPLAY, ANALYSIS AND DISSEMINATION OF METEOROLOGICAL INFORMATION

      Baker, Neal K.; The Aerospace Corporation (International Foundation for Telemetering, 1981-10)
      Meteorological forecasting is a combination of art and science. The need for the human intelligence process still remains. Computers have revolutioned the science of meteorology, but many forecasting tasks still require a large amount of human interpretation and interaction. The forecaster needs to have rapid access to information in order to verify, review, modify, and interpret the computer results. Currently the forecasters review the various data types separately. The system under development will synthesize and display to the forecaster satellite imagery, graphical overlays of the meteorological fields, and alphanumeric reports in a timely manner. A local network will place the forecaster directly on an electronic network which spans the world. Additional tools are provided to the forecaster, such as animation and pseudo-color, to enhance the human recognition processes. Multiple level zooms are utilized to span the range from global to mesoscale phenomena. The forecaster then draws in the human interpreted details. The system merges the human input and adds the computer generated portions. The combined forecast information is disseminated to the weather central and field users. The system will reduce the product generation time by fifty percent. In. addition, special products can be rapidly made up and sent to the users.
    • DISTORTION CONTROL IN ONBOARD PROCESSOR DESIGN

      Lytle, A. C.; The Aerospace Corporation (International Foundation for Telemetering, 1981-10)
      Attention is focused on distortion as an obstacle in achieving design performance goals of onboard processors used in satellite signalling systems. Despreader signal processing loss is expressed analytically as a function of the end-to-end passband differential phase distortion characteristic. Distortion sources are identified and examined for the type and amount of performance degradation. Coping methods are presented. Typical loss values are given graphically for standard reference purposes.
    • DIVERSITY TECHNIQUES FOR OMNIDIRECTIONAL TELEMETRY COVERAGE OF THE HiMAT RESEARCH VEHICLE

      Harney, Paul F.; NASA Dryden Flight Research Center (International Foundation for Telemetering, 1981-10)
      The control system for the highly maneuverable aircraft technology (HiMAT) remotely piloted research vehicle uses airborne and ground-based computers that communicate via uplink and downlink telemetry. It is imperative for this communication to be uninterrupted. Since antenna radiation patterns are normally less than ideal for continuous reception or transmission at all aircraft attitudes, a frequency diversity concept and an antenna diversity concept were developed, implemented, and tested on the HiMAT vehicle. This paper describes the system and the results of the flight tests.
    • DMSP PRIMARY SENSOR DATA ACQUISITION

      Lieske, Roger W.; Westinghouse Aerospace Divisions (International Foundation for Telemetering, 1981-10)
      A Data acquisition system which provides global pictorial cloud cover data for operational military meteorological purposes is described with emphasis on significant design features. These features include near constant geometric resolution through use of an oscillating scanner and variable instantaneous field of view (IFOV), thermal infrared channel output linear with temperature, visible wavelength sensitivity continuous from sub-solar to sublunar, along scan gain control permitting albedo images through the terminator, glare suppression enabling sensing of nighttime scenes in the presence of solar illumination on the spacecraft, wow/flutter correction of video data sampling to that of a reference scan motion, and dual geometric resolution capability from a single detector by synthesis of low resolution data.
    • DoD SATELLITE COMMAND AND CONTROL NETWORK

      Rugg, Charles J.; The Aerospace Corporation (International Foundation for Telemetering, 1981-10)
      Consideration of the command and control of the United States military satellites precipitated a review of the existing satellite control networks. This review cataloged the existing facilities and highlighted their differences and commonalities. Areas that have promise for providing mutual backup and interoperability are noted. A long-range goal is to achieve a degree of interoperability such that command and control of any particular satellite system can be supported by any of several ground control systems.