• 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)
    • 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.
    • 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.
    • 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.
    • Role of TDRSS in Tracking and Data Acquisition

      Spearing, Robert E.; NASA/Goddard Space Flight Center (International Foundation for Telemetering, 1980-10)
      In 1976, NASA committed to development and implementation of the TDRSS as a means of providing improved T&DA services to user satellites. This commitment completes a transition in T&DA operations planning initiated in early 1970's to provide a more efficient network with a broad range of telecommunications capabilities. The integration and operation of the TDRSS within the NASA network is described. Current status and plans for system implementation will conclude the presentation.
    • A PCM-PPK Telemetry System

      You-ping, Li; Institute of Telemetry (International Foundation for Telemetering, 1980-10)
      PCM-PPK telemetry system is one of digitized PPM systems. The PCM-PPK Coverter, synchronous timing circuit and detection device are described. Besides, communication efficiency from viewpoint of information theory is calculated. We come to conclusion, minimum received energy required per bit of PPK system are lower than the PSK and FSK systems.
    • Satellite Position Management

      Baker, J. P.; Davis, R. R.; Lawrence, F. P.; Rodriguez, T. M.; Air Force Systems Command; The Aerospace Corporation (International Foundation for Telemetering, 1980-10)
      Satellites located at synchronous orbital altitudes are a resource vital to the support of military operations. These satellites must be protected from radio frequency interference with their communications and from physical damage that could occur in space. Collateral damage to a synchronous satellite is possible, in the event of a nuclear attack on another satellite, when the spatial separation distance required between satellites is not maintained. Physical damage to a synchronous satellite can also result from collision with another satellite, active or inactive, or collision with space debris objects, some too small to be under surveillance by ground tracking systems. While only a few collision and collision-potential incidents have occurred, the growing number of satellites and objects being placed in synchronous orbit increases the likelihood of problems arising in the future. This paper examines these threats to satellite integrity and operation and the analysis which has been accomplished on ways to protect against them. Satellite Position Management requirements are outlined and problems associated with managing satellite orbital positions are discussed. The Air Force recognizes the need to protect its space resources and is establishing guidelines and responsibilities for offices involved in the management of geosynchronous orbital altitude satellites. The actions being taken by the Air Force and other agencies to regulate satellite spacing and to reduce space debris are enumerated. The paper concludes that full protection will only be realized when DoD combines efforts with NASA and with foreign countries to develop international agreement on satellite orbital spacing and space debris control policies.
    • 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.
    • Lock Detector Algorithms for Synchronization

      Holmes, Jack K.; Holmes Associates (International Foundation for Telemetering, 1980-10)
      Lock detector lock algorithms for both pseudonoise spread spectrum systems and carrier loops are discussed. Specifically, a theory based on discrete time Markov processes employing a generalization of some results of Kemeny and Snell(1) are derived and yield both the mean and the variance of the time it takes to have a false dismissal and a false alarm. Some examples of typical algorithms are given.
    • 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.
    • 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.
    • 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.
    • The Effects of Tape Dropouts on Pulse Compression Recording

      Waggener, W. N.; Sangamo Weston, Inc. (International Foundation for Telemetering, 1980-10)
      It is widely recognized that tape dropouts are the major impediment to error-free recording in high density digital recorders (HDDR). Conceptually, the effects of tape dropouts on error performance can be combatted by error correcting codes, signal design or a combination of the two. In this paper the effect of tape dropouts on wide time-bandwidth signals is considered. Wide time-bandwidth signaling techniques, commonly refered to as pulse compression, would appear to be capable of combatting the effects of short tape dropouts. Although the wide time-bandwidth signals are, to a certain degree, immune to short signal dropouts, an excessive performance penalty is paid when dropouts exceed about 10% of the signal duration. The effects of tape dropouts are shown to effectively reduce noise margin by decreasing the signal detection filter output and by introducing intersymbol interference through increased sidelobe levels.
    • Ground Mobile Forces Tactical Satellite Terminals

      Rurak, Stephen F.; US Army Satellite Communications Agency (International Foundation for Telemetering, 1980-10)
      To supplement its communication capabilities, the US Army has developed a family of small, mobile, relatively low cost, Satellite Communications Terminals. Designated as AN/TSC-85 and AN/TSC-93, the Ground Terminals provide Satellite Communication links using the SHF Band. The terminals have a similar design resulting in a high degree of commonality allowing for lower logistics and operational costs. A special signal processing equipment permits nodal (multi-point) and non-nodal (point-to-point) communications. Both terminals are designed to operate from a standard, field power generators as well as from a variety of other power sources. The terminals can establish communications within thirty minutes of arrival on site.
    • Scientific Balloon Telemetry, Command and Data Recording

      Cooper, Oscar L.; National Scientific Balloon Facility (International Foundation for Telemetering, 1980-10)
      The free balloon provides science with a very useful means of reaching the upper levels of the earth's atmosphere. To take full advantage of the balloon's capability as a scientific platform, methods for determining the balloon's trajectory, recovering the scientific data and controlling the scientific equipment and balloon system are required. Several modes of communication are available to accomplish this task. This paper describes the techniques used by the National Scientific Balloon Facility for data recovery, data presentation, recording and system control including standard telemetry methods and current and proposed satellite techniques.
    • 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.
    • GPS Receiver Simulation and Software Verification

      Holmes, Jerry D.; Budde, Steven R.; Texas Instruments Incorporated (International Foundation for Telemetering, 1980-10)
      The GPS receiver is a receiver capable of tracking the signal from a Global Positioning System (GPS) satellite containing carrier and code tracking loops characterized by their bandwidth and order. A math model of a CPS receiver that uses Monte Carlo techniques to simulate the many effects to be modeled if one is to predict the performance of a GPS receiver when it is operating near its SNR threshold is described. Among these are: (1) predetection filter characteristics, (2) dynamic stress effects, (3) phase or frequency loop error characteristics, (4) envelope detector algorithm, (5) postdetection filtering characteristics, (6) code loop error characteristics, (7) noise sample generation with proper degree of correlation, (8) effect on carrier and code loops when carrier oscillator has a frequency error, (9) effect on carrier and code loops when code loop has a phase error, (10) sampled data effects on carrier and code loop filters and digital oscillators, and (11) threshold improvement as a result of narrower loop bandwidths when inertial aiding is possible. By imbedding a modified version of this GPS receiver model in an interactive software development tool, the verification of actual digital receiver software in a simulated real-time environment can be performed. The design, implementation, and use of such an interactive software development tool is described in the second half of this paper.