• 20 GHz Active Aperture for Communication Satellites

      Jones, Donald E.; Motorola, Inc. (International Foundation for Telemetering, 1980-10)
      The trend to higher frequencies for satellite to earth communications, together with requirements for increased reliability and graceful degradation, has resulted in the need for a 20 GHz active aperture transmitting array. In this paper the preliminary design of such an array is discussed. The array is designed for 35 dB of gain and -30 dB sidelobes. Quantized amplitude tapering, gain distribution, phase shifter quantization, prime power requirements, array and element trade-offs are discussed. The impact of multiple beam operation for frequency reuse is addressed.
    • 30/20 GHz Demonstration System for Improving Orbit Utilization

      Holmes, W. M., Jr.; TRW DSSG (International Foundation for Telemetering, 1980-10)
      The NASA LeRC 30/20 GHz Satellite Communications Program is developing a number of technologies to reduce satellite orbit/spectrum crowding and prevent saturation of our domestic United States Communications capabilities in the 1990 to 2000 decade. Developing the basic hardware technology to operate at 30 and 20 GHz provides 2.5 GHz of new communications bandwidth. This 2.5 GHz additional communications bandwidth is not the primary benefit of the program, however. Rain losses are severe at 30 and 20 GHz, and innovative techniques are required for systems which are both reliable and economic. Techniques being developed include large satellite antennas with simultaneous multiple fixed and multiple scanning beam capabilities. These provide high antenna gain to increase communications margin and frequency reuse capability through beam isolation, while providing complete coverage of the United States. Effective communication bandwidths from a single satellite location can reach ten's of gigahertz, with the communication capacity tailored to match the very nonuniform geographic demand pattern. Satellite onboard processing consisting of demodulation, adaptive forward-error-correction (FEC) decoding and coding, routing of hundreds of thousands of channels to thousands of terminals, and remodulation with independently optimized uplink and downlink modulation structures is being developed. The onboard processing reduces the scanning antenna requirements, allows more effective frequency reuse, and increases the rain margins by adoptively using system margins to support terminals currently experiencing rain. All of the functions described can be performed with reasonable satellite weight, thermal, and power impacts by using large scale integration (LSI) to implement the digital data processor. By designing the onboard processor with parallel internal structure, the hardware can be made extremely reliable (high level redundancy) and the number of LSI chip types required is relatively small. The antenna and onboard processing techniques are readily adaptable to C-band and Kuband, as well as Ka-band. Deployable antennas may be required at the lower bands, but precision deployable antenna designs are available and the feed structures scale directly. Frequency reuse of all three commercial communication bands should greatly ease the orbit crowding problems now being experienced in C-band, and should allow United States domestic communications to accommodate any desired expansion in the next two decades.
    • Adaptive Rain Fade Compensation

      Rautio, James C.; General Electric Space Division (International Foundation for Telemetering, 1980-10)
      Any satellite communications system operating near 20 GHz will occassionally experience deep fades due to rain attenuation. To maintain a high grade of service in spite of these fades such a system must have a large available margin. An approach to providing this margin in a high capacity FDMA communications satellite without requiring exorbitant spacecraft power or ground station antenna diversity is to dynamically provide a large margin to those links experiencing deep fades while maintaining only a small fade margin on all other links. This paper presents a brief description of FDMA systems; single beam SCPC operation, multiple beam satellite switched FDMA (SS-FDMA),and investigates the optimization of the dynamic FDMA links in a severely fading environment. A solution taking into consideration transponder intermodulation distortion, cochannel and cross polarization antenna interference (in multiple beam antenna systems) and rain fade statistics is derived. The system is optimized with respect to minimum required thermal signal to noise ratio under peak interference conditions. A sample system configuration is presented which shows that such systems can achieve availability approaching 0.9999 at Ka-Band.
    • 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.
    • Advanced Onboard Signal Processor

      Works, George A.; Basel, John; Raytheon Company (International Foundation for Telemetering, 1980-10)
      The Advanced Onboard Signal Processor (AOSP) in a distributed signal processing computer under development for space radar, electro-optic and communications applications in the post-1985 time frame. The processor architecture is based on an arbitrary-topology network of identical processing elements specialized to perform signal processing and controlled by a distributed operating system. Both the operating system and applications programs are written in a high order language which is efficiently supported by the processing elements. Examples of communication signal processing are presented which show the suitability of AOSP for this application. The design has been validated by extensive simulation and is presently in the breadboard hardware phase.
    • AFSCF Planning Towards the 1990's

      Rugg, Charles J.; The Aerospace Corporation (International Foundation for Telemetering, 1980-10)
      The Air Force Satellite Control Facility (AFSCF) came into being over twenty years ago, and since then has evolved into a satellite support network of major national importance. The present configuration of the AFSCF includes seven Remote Tracking Stations (RTS's) situated around the globe plus a central control facility, the Satellite Test Center (STC), located in Sunnyvale, California. (See Figure 1.) Ongoing plans will provide for significant upgrades and additions to the AFSCF network. Two of these which will have a major influence on the operations of AFSCF into the 1990's are the centralization of the real-time processing capability at the STC (Data Systems Modernization) and the implementation of a Consolidated Space Operations Center (CSOC) tentatively planned to be constructed in Colorado Springs, Colorado. These two upgrades to the AFSCF are discussed (see Figure 2) in detail elsewhere in these proceedings under their respective titles.
    • The Air Force Satellite Control Facility

      Konopasek, L. Ken; Kluetmeier, Jorn; The Aerospace Corporation (International Foundation for Telemetering, 1980-10)
      The Air Force Satellite Control Facility (AFSCF) originated over twenty years ago, and has evolved into a global satellite support network. This global network includes seven Remote Tracking Stations (RTS's), support elements, and the Satellite Test Center (STC) located in Sunnyvale, California. The AFSCF provides real-time telemetry, tracking, and command support to Department of Defense (DOD) spacecraft and launch vehicles. Since its inception in response to changing DOD space support requirements, the SCF network has grown through expansion and modernization of its tracking, data processing, and communication capabilities. This paper discusses the past, the present, and projected AFSCF in support of the DOD space programs and including the Space Transportation System (STS).
    • Ampex SHBR System

      Wood, Tracy G.; Ampex Corporation (International Foundation for Telemetering, 1980-10)
      An update on the Ampex Super High Bit Rate (SHBR) recorder program will be provided. Last year a paper was presented which reviewed the fundamental elements of the rotary helical approach being developed. This year's paper will concentrate on progress made during the past year, including photographs of engineering testbeds. Summaries of performance data which has been measured and demonstrated will be reviewed as it relates to the ultimate implementation of a 1 GIGABIT/SEC recorder/reproducer with continuously variable data rates.
    • Analytical Simulation of Nonlinear Satellite Links

      Braun, W. R.; LinCom Corporation (International Foundation for Telemetering, 1980-10)
      Performance predictions for nonlinear digital satellite channels are usually obtained by either purely analytical methods or Monte Carlo simulations. These approaches must work with very simple channel models or they become extremely costly to use. In this paper it is shown that through analytical modeling of the effect of the nonlinearity on the uplink waveform it is possible to obtain approximate performance predictions with a minimum of computer time. It is demonstrated that the results agree quite well with Monte Carlo simulations and that meaningful tradeoffs can be, performed with this tool.
    • Application of Advanced On-Board Processing to Satellite Communications - Cost/Performance Implications for Technology Development

      Ruddy, J. M.; White, B. E.; The MITRE Corporation (International Foundation for Telemetering, 1980-10)
      Rapidly growing communications services are creating a demand for large capacity communications satellites which are efficient and economical. This demand, coupled with the need for affordable earth terminals and the requirement for a mix of user types, means that future communication satellites must support a complex system structure. Technological development and implementation are clearly needed. The focus of this paper is on-board processing techniques and related technical issues regarding implementation of a multibeam communications satellite which would service a wide range of users in the 1990 time frame. The effect of various forms of on-board signal processing on satellite communication system performance and cost in the 20/30 GHz band is examined. The implications for technological development are discussed in the context of a specific system architecture suitable for use by wideband high rate trunking users and lower rate customer premises services. The particular impact of processing satellite architectures on earth terminal costs is emphasized.
    • Application of Intersatellite Links to Collocated Telecommunications Satellites

      Welti, G. R.; COMSAT Laboratories (International Foundation for Telemetering, 1980-10)
      A satellite communications system employing a pair of collocated advanced satellites is examined. The new 6/4-GHz bands allocated by the 1979 WARC are exploited to provide a nominal bandwidth of 5,440 MHz for a total capacity of 56,000 channels. The two satellites have an intersatellite link operating in the 32.5- and 23-MHz bands over a 6-km distance. Up to ten 80-MHZ transponders can be cross-strapped. The total mass of each spacecraft is about 1,135 kg.
    • Application of Telemetry to Geological Prospecting in China

      Fan-shuan, Zeng; Feng-kuan, Wang; Beijing Research Institute of Telemetry (International Foundation for Telemetering, 1980-10)
      This paper describes the application of telemetry to petroleum prospecting and coal mine prospecting in China and gives an introduction to the operational features of petroleum prospecting and coal mine prospecting. The logarithmic coding and depth synchronous coding have been adopted to fit these features. The paper also introduces briefly the system scheme and the effectiveness in use. The results of the equipments have abundant capacity, large dynamic range, comparatively high accuracy, flexibility, the high speed gained from computer-aided data processing, and the advantage of being easy to use and less expensive, and consequently are applicable to the developing countries.
    • 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.
    • The Communications Platform -- Key to Affordable Services for the Small User

      Bowman, R. M.; General Dynamics (International Foundation for Telemetering, 1980-10)
      The paper will start with a discussion of the economics of communications and small users. It will be shown that the key is reduction of ground segment costs (which today far exceed that of the space segment) by elimination of the "tails" and by reducing the size and complexity of earth stations. The resulting services are a Customer Premise Services (CPS) network and a mobile service. The basic technical requirements of these services are discussed.
    • 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.
    • 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.
    • Consolidated Space Operations Center

      Moffat, Margaret H.; Hollander, Sidney; The Aerospace Corporation (International Foundation for Telemetering, 1980-10)
      Now in the planning stage by the Air Force Systems Command Space Division, the Consolidated Space Operations Center (CSOC) will be a secure, dedicated space control center that will provide the Air Force enhanced command and control capability in the late 1980's and 1990's. Tentatively to be constructed in Colorado Springs, Colorado for an initial operational capability date of mid-1986, the CSOC will include a Satellite Operations Center (SOC) and a Shuttle Operations and Planning Center (SOPC). The SOC, an integral part of the Air Force Satellite Control Facility (AFSCF) network and functionally identical to the Satellite Test Center (STC) in Sunnyvale, California, will perform its command and control functions with a modernized data system now under development at the STC, and will support its assigned AFSCF workload. Also, in the event of a catastrophic failure, the SOC will provide austere backup support for workloads normally assigned to the STC, and vice versa. Additional land is being acquired to accommodate the construction of facilities for major new space programs as required. The SOPC, functionally equivalent to portions of the NASA Johnson Space Center Space Shuttle Complex, will perform preflight, flight, and postflight operations necessary to satisfy DOD Space Shuttle vehicle payload mission objectives. The SOPC and the Johnson Space Center (JSC) will be interoperable so as to provide limited backup support for DOD or NASA Space Shuttle missions in the event of catastrophic or extended failure at either location. The development of the CSOC requires major architectural changes for both the AFSCF and NASA. These changes include an expansion of the current AFSCF wideband communications system; interfacing of the AFSCF and NASA communications networks; inclusion of a 32 megabit-per-second (or higher) telemetry processing capability for scientific experiments that will be flown during Shuttle sortie missions; and provision of systems to coordinate operations between Shuttle payload specialists and associated ground controllers.
    • Control and Data Transmission System for a Balloon-Borne Ion Mass Spectrometer

      Sukys, Raimundas; Rochefort, J. Spencer; Northeastern University (International Foundation for Telemetering, 1980-10)
      A balloon-borne instrument package is currently being developed by the Aeronomy Division of the Air Force Geophysics Laboratory. The primary instrument is a quadrupole mass spectrometer. Its task is to detect ambient ion and neutral clusters at altitudes of 30 to 40 kilometers. Positive and negative ions in the range of 14 to 1000 atomic mass units (amu) are to be investigated. An aspirated Gerdien condenser and a low emission potential probe are included as supporting instruments. A flight from the AFGL Balloon Facility at Holloman AFB, New Mexico is planned for spring, 1981.
    • Cost Considerations for EHF Satellite Communications User Terminals

      Andrews, E. J.; Robinson, E. S.; Rockwell International (International Foundation for Telemetering, 1980-10)
      Mobile satellite communications at UHF have gained wide acceptance in the past several years. This acceptance has been largely a result of the improvement in communication reliability over other long-range systems such as HF. Deficiencies, however, have been noted with respect to the performance of UHF satellite communication (SATCOM) systems where anti-jam (AJ) or low probability of intercept (LPI) characteristics are of importance. Recent advancements in technology coupled with increased requirements for improved AJ and LPI have focused attention on the EHF frequency range for evolutionary replacement and/or augmentation of UHF SATCOM systems. RF equipment in this frequency range has the potential for the implementation of highly compact terminals for mobile application such as required for airborne force elements. In the next 5-10 years, a wide range of technologies will be applied to the development of EHF user terminals. Critical trade-offs exist between satellite and terminal complexity as well as within the terminal itself. Within the terminal, antenna gain versus HPA power, antenna mounted solid-state PA's versus TWT PA's, phased arrays versus advanced reflector antennas all must be considered. Although the antenna and HPA are the most significant cost drivers, secondary trade-offs, such as antenna gain versus use of paramps or FET's, and synthesizer approaches for fast hop and signal processing implementation also must be addressed. This paper addresses a typical terminal for a small mobile user such as an airborne force terminal. Typical system and spacecraft characteristics are defined and tradeoffs carried out on a parametric basis between various terminal elements to establish cost-performance relationships.