• Super High Bit Rate Recording

      Wood, Tracy G.; Ampex Corporation (International Foundation for Telemetering, 1979-11)
      A radically different magnetic recording approach is proposed to solve the very high density and very high data rate requirements of the 1980's. In direct contrast to the industry's traditional approach of head-per-track longitudinal recording is a multi-track rotary helical recorder using narrow tracks. This technique is described. These narrow tracks, in conjunction with a novel development called "Automatic Scan Tracking" (AST), make possible the development of a family of recorders with data rates up to one (1) gigabits per second with user packing densities of five (5) megabits per square inch and a bit error rate performance better than one (1) part in a million (106) without aid of error detection and correction codes.
    • The LEASAT Communications Satellite

      Dutcher, G. L.; Lankford, J. G.; Hughes Aircraft Company (International Foundation for Telemetering, 1979-11)
      Beginning in 1982 communication services will be provided to the U.S. Navy by a series of UHF communications satellites known as LEASAT. The communications payload will be carried on a new spacecraft bus developed as an optimum bus for space shuttle launches; the program is the first of its kind to take advantage of the full 15 foot shuttle payload bay diameter. Several new spacecraft design concepts are employed in this optimized bus. The communications payload incorporates transponders in the UHF and SHF regimes. Four distinct types of transponders are employed: wideband, narrowband, relay, and fleet broadcast. The functional characteristics of each type is described in detail. The frequency plan leads to a significant potential for passive generation of intermodulation products, and intermodulation considerations are an integral part of the spacecraft design.
    • Correlation of Tape Dropouts with Data Quality

      Schoeck, Kenneth O.; Kobylecky, George M.; Vandenberg Air Force Base (International Foundation for Telemetering, 1979-11)
      When recording and reproducing telemetry data, signal dropouts are a prime concern to most tape users. The effect of particular depths and lengths of dropouts on data quality must be known before the acceptability of a tape for a specific application can be determined. This paper discusses the correlation of tape dropouts with data quality when recording predetection and post-detection telemetry data and IRIG timing on wideband instrumentation tape, as well as methods of reducing dropouts.
    • The Command and Data Management System of Spacelab

      Bolton, Gordon R.; European Space Agency (ESA) ESTEC (International Foundation for Telemetering, 1979-11)
      This paper describes the Spacelab command and data management system and its support capabilities for various types of experiments in terms of data processing, display, recording, and multiplexing.
    • A Compatible STS/PAM D/RCA SATCOM Telemetry and Command System

      Hoedemaker, R.; Staloff, C.; RCA Astro-Electronics (International Foundation for Telemetering, 1979-11)
      This paper presents a solution to the problem of providing the electrical interface with the NASA Shuttle and PAM D for an RCA Satcom Communications Satellite. The paper addresses the transition to the NASA Shuttle from the present era of expendable launch vehicles as it applies to the command and telemetry electrical interfaces. Final preparation of the spacecraft for launch into the transfer orbit rests with the Orbiter crew rather than the spacecraft contractor launch team. The added dimension of crew safety and the importance of simplifying the preparation task led the requirement for Electrical Airborne Support Equipment (EASE). The conceptual design of this microcomputer-based equipment is described. The EASE monitors the health of the spacecraft and takes adaptive action where appropriate. It also sends prestored command lists to the spacecraft in response to crew-initiated keyboard command functions.
    • Inertial Upper Stage/Shuttle Orbiter Communications

      Huth, G. K.; Udalov, S.; Axiomatix (International Foundation for Telemetering, 1979-11)
      The Inertial Upper Stage (IUS) system is intended for DOD and NASA space vehicle (S/V) launches from the Shuttle Orbiter. Prior to and during the IUS launch, commands must be transmitted to the S/V and IUS and the telemetry data must be communicated to the Orbiter. This paper describes the communication links between the IUS and the Orbiter, with particular emphasis on the RF link equipment and performance. The transponder equipment carried on board the IUS system is also described.
    • Navy Shipboard Weapon Information Telemetry System

      Dahl, Ernie A.; Bates, L.; Naval Ship Weapon Systems Engineering Station (International Foundation for Telemetering, 1979-11)
      The paper presented by NSWSES at the 1975 ITC Conference in Washington, DC, described the Portable High Frequency Telemetry System (PUTTS) being assembled for NATO. This system used the best of the then standard state of the arts commercial components and was used for shipboard missile data receiving/recording and for quick look missile performance evaluation. In 1977 the Naval Sea Systems Command made funds available to update the AN/SKQ-3 system by utilizing the RF assembly similar to that used in PUTTS. This new RF assembly provided dual antennas for (1) a wide angle for verticle launch and initial acquisition; (2) narrow beam high gain for long range tracking. The RF unit also included frequency scan with automatic lock when a signal was received, and sector search. In 1978 funding was received from Australia and Iran to procure additional PUTTS. These units (PUTTS III) were updated to handle faster intercept rates as well as improved range tracking and adapt the new RF features from the SKQ-3 Mod. Added to this were the capability to handle both PAM and PCM data with light weight hardware. These systems were completed and the Australian unit system was delivered after acceptance tests with U.S. fleet operation in the Gulf of Mexico. As a result of these successful improvements a new portable system has been built to (1) adapt microprocessors to the set-up of data format; (2) Provide automatic selection remote control of the RF head within the antenna frame; (3) provide the basic data to make automatic processing possible when and if desired; (4) Add the new low noise GASFET preamp to the system to increase the range; (5) Add capability for four receivers in the space presently occupied by the dual receivers to permit the handling of the new missiles with dual RF outputs and (6) provide the capability of system checking of all modules from the antenna through the system to the paper read-out device. This paper now presents the new updated system combining the state of the art development in programming, remote control, low noise preamps, miniature RF assembly, matrix control programming as well as automatic data set up and selection for data processing.
    • DMSP Block 5D-1 Computer Controlled Spacecraft

      McElroy, Stephen M.; Gomberg, Louis; Beest, Roger Te; SAMSO; RCA/AED (International Foundation for Telemetering, 1979-11)
      The Defense Meteorological Satellite Program (DMSP) Block 5D-1 satellite is the first of a new generation of DMSP long life satellites to utilize onboard programmable computers for spacecraft control functions. During ascent and orbit injection the computers perform the navigation, guidance, and control functions autonomously; during on-orbit operations, they perform attitude determination and control, command and control, and miscellaneous other control functions, with only modest interaction from the ground. Four DMSP Block 5D-1 satellites employing these computer controls are currently on orbit and operational. On-orbit experience shows that performance has exceeded all expectations with respect to reliability and satellite life-time. In addition to providing the control functions for which they were designed, the computers have provided additional benefits by allowing the control systems to be reprogrammed from the ground to overcome hardware failure and degradation in other on-board components. This paper describes the DMSP mission, gives a brief overview of the integrated spacecraft system configuration, and provides the details of the control systems used in the various mission phases. The hardware and software portions of the control systems are described and some examples are provided showing how the reprogrammable capability allowed several orbital anomalies to be overcome and satellite life extended.
    • Space Shuttle Technology Flight Instrumentation

      Dunstan, John; Rockwell International (International Foundation for Telemetering, 1979-11)
      The launch and orbital phase of the Shuttle is comparable to the Apollo flight. The entry phase, on the other hand, presents many new challenges to a reusable vehicle. To explore this area and provide more detailed data than that required for flight, the Shuttle technology flight instrumentation (TFI) system was proposed. This paper discusses the TFI, which records flight data during the operational phase of the Space Shuttle. It also deals with pertinent background information, such as Shuttle operation, flight verification, and instrumentation provided for the developmental and operational phase.
    • International Telemetering Conference Proceedings, Volume 15 (1979)

      International Foundation for Telemetering, 1979-11
    • Space Shuttle Communications and Telemetry - An Update

      Hoagland, J. C.; Rockwell International (International Foundation for Telemetering, 1979-11)
      During operational space flight, the communications and telemetry subsystem of the Space Shuttle orbiter uses S-band and Ku-band links to provide, in addition to tracking, reception of digitized voice, commands, and printed or diagrammatic data at a maximum rate of 216 kilobits per second (kbps). The subsystem also provides a transmission capability for digitized voice, telemetry, television, and data at a maximum rate of 50 megabits per second (mbps). S-band links may be established directly with a ground station and both S-band and Ku-band links may be routed through NASA's tracking and data relay satellite system (TDRSS). A simultaneous capability to communicate with other satellites or spacecraft, using a variety of formats and modulation techniques on more than 850 S-band channels, is provided. Ultrahigh frequency (UHF) is used for communication with extravehicular astronauts as well as for a backup subsystem for state vector update. Audio and television subsystems serve on-board needs as well as interfacing with the radio frequency (RF) equipment. During aerodynamic flight following entry, the S-band link can be supplemented or replaced by a UHF link that provides two-way simplex voice communication with air traffic control facilities.
    • Time and Frequency Transfer by the Master-Slave Returnable Timing System Technique - Application to Solar Power Transmission

      Lindsey, W. C.; Kantak, A. V.; LinCom Corporation (International Foundation for Telemetering, 1979-11)
      A classical method of transfering time and frequency from one network node to another is the Master-Slave (MS) technique. This method, though fairly simple and easy to implement, is plagued with the problems introduced by the variable propagation path delays between network nodes. The master slave returnable timing system (MSRTS) technique presented in this paper offers the flexibility and simplicity of the well established MS approach; however, it provides for a novel automatic delay compensation feature. Delay compensation between two nodes is achieved by measuring the delay between the two nodes and then using this knowledge about the delay to automatically update the phase of the transmitting node such that the phase at the receiving node is independent of the delay between the two nodes. A theory and analysis of this system is presented here in a noise free environment and an extension is made to cover the propagation of internally generated noise (clock phase noise) through the network.
    • Laser Sources and Space Optical Communications

      Barry, J. D.; Hughes Aircraft Company (International Foundation for Telemetering, 1979-11)
      Intersatellite optical communication systems may be based on a number of conventional laser sources allowing wavelength and operating parameter selection, and system optimization to a particular satellite system. Laser sources which are presently available for satellite use, due to the current status of technical and engineering developments, include the HeNe gas laser operating at 632.8 nm, the GaAlAs diode laser operating at 800 to 900 nm, the Nd:YAG laser operating at 1064.2 nm and 532.1 nm, and the CO₂ laser operating near 10600 nm. The applicability of each laser source to a satellite communication system is determined by on orbit requirements and attitude stability of the satellite, by the performance characteristics and operating needs of the laser source and its associated support equipment, and by the optical propagation properties of the laser system. Two general levels of the optical communication must be considered; initial satellite to satellite acquisition and possible reacquisition, and the transmission of data at the required rate. The general characteristics and system properties must evolve from the interrelated factors and occasionally contradictory requirements. It is the purpose of this presentation to provide insight into the applicability of a laser communication system to space and to indicate the dominating factors in the selection of a laser system.
    • Data Pattern Sensitivity in Tracking Performance of an AC Coupled Costas Loop with Hard-Limited In-Phase Channel

      Park, Young H.; California Institute of Technology (International Foundation for Telemetering, 1979-11)
      This paper is concerned with data pattern sensitivity in carrier tracking performance of an AC coupled Costas loop with a suppressed BPSK signal. The signal amplitude suppression factor is derived as a function of data "asymmetry ratio" - the ratio of "1"s to the total number of bits in a period of a periodic signal. For an asymmetric pattern, the effect of AC coupling is noticeable whereas there is almost no effect for symmetric squave wave. The tracking performance with an asymmetric pattern is worse than that with a symmetric pattern. However, it is also shown that as expected, the tracking performance of a DC coupled loop with an asymmetric pattern is better than that with a symmetric pattern.
    • Generalized Feedback Decoding of Convolutional Codes

      Ng, Wai-Hung; The Aerospace Corporation (International Foundation for Telemetering, 1979-11)
      The use of convolutional codes with feedback decoding is the most common error-correction technique in simple communication systems. A drawback of conventional feedback decoding is the limitation to a class of self-orthogonal codes which, in general, are non-optimum. Based on distance properties of the utilized code and test-error pattern analysis, we propose generalized feedback decoding that does not have the above mentioned limitation. This is minimum distance decoding and can be applied to any convolutional code while still maintaining its simplicity. Therefore, it has the advantage of being easily adopted in the existing systems. We can use complicated Viterbi or sequential decoder in large terminals and, with the same code, use the proposed decoder in small terminals; otherwise, both large and small terminals must utilize the same type decoder. Also, we may use the proposed decoding scheme to simplify and accelerate sequential type decoding. In addition, by means of the special recovery property of convolutional codes, advanced ARQ retransmission systems could be much improved; several practical applications are suggested and discussed in the last section of this paper.
    • Multigigabit Satellite On-Board Signal Processing

      Holmes, W. Morris; TRW Inc. (International Foundation for Telemetering, 1979-11)
      Satellite communications in the late 1980s and 1990s must provide reliable high-rate communications between very small inexpensive terminals with routing flexibilities approaching today's telephone system. The capabilities needed for successful competition with established and evolving terrestrial communications systems can be provided most efficiently using Satellite On-board Signal Processing. The rapid improvement of high-speed digital technology makes it possible and costeffective to demodulate, process, and remodulate individual data streams with rates approaching a gigabit. System processing capacity of several gigabits (ten in the example described) through a single satellite can be provided. The satellite communications system described provides communications for very small and very large (trunking) users. Independent combinations of FDMA and TDMA are used in the uplink and downlink designs to minimize terminal costs. Signal routing for small users is accomplished by a digital store-and-forward technique which greatly simplified the terminal receiver, compared to satellite-switched TDMA. Different processing techniques are used for very high data rate users, but complete interconnectivity between all users is maintained. This avoids double-hop routing with excessive transmission delays. On-board processing allows use of innovative responses to rain attentuation without requiring expensive, large signal-power margins. Terminal synchronization and timing is greatly simplified without a significant increase in satellite complexity, by integrating the synchronization loops with the downlink communication TDMA burst structure.
    • Space Shuttle Payloads and Data-Handling Accommodations

      Teasdale, William E.; Tu, Kwei; Lyndon B. Johnson Space Center; Lockheed Electronics Company, Inc. (International Foundation for Telemetering, 1979-11)
      The primary objective of the Space Shuttle Program is to provide an economical space transportation system that will support a wide range of scientific, defense, and commercial applications in Earth orbit. The Shuttle will be a manned, reusable space vehicle designed to accommodate these applications. The advent of the Space Shuttle will usher in an era of space industrialization and utilization which undoubtedly will result in new products, new services, and new sources of energy.
    • An Optimum Asymmetric PN Code Search Strategy

      Holmes, J. K.; Woo, K. T.; Holmes Associates; Aerospace Corporation (International Foundation for Telemetering, 1979-11)
      A theory is developed which allows one to obtain the optimum asymmetric acquisition search strategy of a PN code despreader when the a priori probability density function is given. The results developed here extend the theory of an optimum symmetric PN code search strategy to the more easily implementable asymmetric search pattern. In the case when the a priori probability density function is Gaussian and for an environment such as the TDRSS (Tracking Data Relay Satellite System), the acquisition time is reduced by about 40% compared to the more standard uniform sweep.
    • A High Performance 8 GHz, 8 PSK Digital Radio

      Russo, Giuseppe G.; Hartmann, Paul R.; Rockwell International (International Foundation for Telemetering, 1979-11)
      Rapid growth and modernization of microwave communications is currently taking place in both the commercial and military environments. Much of this growth is being accomplished through digital transmission, and calls for efficient utilization of frequency spectra allocated for LOS communications. As the bit efficiencies and data rates of digital radio systems have increased, the problems associated with multipath propagation phenomena have become more evident. This is due to the fact that the transmitter signal is randomized before transmission and the system behaves as though it has full loading at all times. To minimize outages and to meet path availability objectives, diversity protection alone, in many instances, is not sufficient. However, diversity protection, coupled with an acaptive equalizer, will meet the objective in all but a few severe cases. This paper describes a digital radio system operating in the 8 GHz band with 8 PSK modulation and nominal data rates of 45 Mb/s or 90 Mb/s. Multipath propagation and its effects on digital transmission are discussed. Improvements in bit error rate threshold obtained through the use of an adaptive equalizer designed into the receiver are also presented.
    • Future Performance Limitations for Ground and Spaceborne Millimeter Wave Receiver Systems

      Cardiasmenos, Apostle G.; Alpha Industries (International Foundation for Telemetering, 1979-11)
      Recent developments in the technology for millimeter wave receiving equipment make a much more promising case for increased utilization of millimeter waves in telecommunication links. Low system noise figure coupled with large achievable antenna gain in small earth terminals make a good case for millimeter direct satellite broadcast links. Future technology trends indicate that use of the 80-100 GHz region of the spectrum will be beneficial and useful in the 1985-1990 timeframe.