• 20/30 GHz Satellite Systems Technology Needs Assessment

      Stevens, Grady; Wright, David; National Aeronautics and Space Administration (International Foundation for Telemetering, 1978-11)
      NASA is involved in exploring the potential of the 20/30 GHz bands as evidenced by the propagation work in the ATS series by NASA-Goddard and, more recently, by the systems and market effort by NASA-Lewis. This paper focuses on the system and market work done by NASA-Lewis. Included are results of previous contractual and in-house studies, as well as preliminary results of on-going market and system studies. Baseline concepts for evaluating technology needs are also included.
    • Acquisition Processing for the TDRSS Simulator

      Heitzman, R. E.; Horwood, D. F.; Rose, B. E.; Hughes Aircraft Company (International Foundation for Telemetering, 1978-11)
      The TDRSS simulator forward link acquisition process requires that the epoch and frequency of the spreading code be acquired, and that the incoming carrier be phase locked. The time required for these two acquisitions must meet a specification of 20 seconds for S band and 4 seconds for K band operation. Calculations for the time required to acquire the carrier show that with the allowable sweep rates and frequency uncertainties the acquisition time specifications cannot be met with conventional sweep lock circuitry. Parallel processing is possible, but the requirements on local frequency control become difficult, and the additional circuits required make this approach unattractive. Because of these considerations, a frequency control strategy was developed which reduces the carrier acquisition time to fractions of a second. The specified acquisition time can then be allotted almost entirely to the spreading code acquisition process. This strategy is described in detail, including an experimental verification of the technique. The technique has an additional advantage of eliminating false lock to data sidebands in the carrier loop.
    • Advanced Marine Information Delivery

      Durstenfeld, Richard; NASA Jet Propulsion Laboratory (International Foundation for Telemetering, 1978-11)
      SEASAT-1 is now an established fact. It is providing continuous sensing of the world's oceans and related meteorological phenomena from its satellite platform in space. What is the next step? This paper considers the information delivery challenges of the follow-on programs to SEASAT as they progress through the next decade. These include coping with the vast quantities of data to be transferred, fulfilling the temporal requirements on data delivery, and the trade-offs and developments needed to accomplish the various levels of processing required to convert sensor output into useful information. A need for critical development is clearly identifiable in the areas of low cost ground terminals capable of image extraction and image correlation; dynamic data assimilation to accomodate forecasters; low resolution onboard correlators; and low cost user advisory (display) terminals. The system planners for the Ocean Satellite advanced programs are utilizing an end-to-end data systems approach in meeting these challenges. The economic and scientific impact of delivering decision making information to the marine community in real time and in useful form is recognized and is potentially achievable.
    • Aging of Magnetic Recording Tape

      Cuddihy, Edward F.; California Institute of Technology (International Foundation for Telemetering, 1978-11)
      The composition of magnetic recording tape is about 25 wt. % magnetic oxide particles, and 75 wt. % polymeric materials. With the exception of the recording properties of tape which are ascribable to the magnetic oxide particles, almost all of the other properties important to tape, such as aging, storage, tracking, etc., are ascribable to the chemical, physical, and mechanical properties of the polymeric materials.
    • Air Force Space Laser Communications

      Roland, Jay R.; Whited, Charles E.; Los Angeles Air Force Station (International Foundation for Telemetering, 1978-11)
      The Air Force Space Laser Communications (LASERCOM) Program started with system concept and component design in the early 1970's at the Air Force Avionics Laboratory. The communications system that evolved demonstrated, in 1973, data rates up to one gigabit per second with a bit error rate of 10⁻⁶ for 40,000 kilometer simulated links. System capabilities were demonstrated during the period 1975 to present using an engineering feasibility model of a gigabit-per-second space qualifiable transmitter and a brassboard receiver. The next phase of the program started in September of this year when the LASERCOM system began operation outside of the laboratory environment at the White Sands Missile Range in New Mexico. This six-phase demonstration will include ground-to-ground links up to approximately 20 kilometers and aircraft-to-ground links up to approximately 50 kilometers. During these demonstrations, dynamic far-field acquisition, tracking, and two-way communications will be demonstrated. The performance characteristics of the LASERCOM system make its potential application to certain satellite-satellite and satellite-aircraft links unique, while other potential LASERCOM links require a detailed cost analysis of the current investment in radio frequency terminals and systems versus the cost of developing and deploying LASERCOM terminals and systems. There are also some communications links that can be most effectively satisfied by a hybrid LASERCOM and radio frequency system.
    • An Airborne Meteorological Data Collection System Using Satellite Relay (ASDAR)

      Bagwell, James W.; Lindow, Bruce G.; National Aeronautics and Space Administration (International Foundation for Telemetering, 1978-11)
      The Aircraft to Satellite Data Relay (ASDAR) project was begun in 1975 as a joint NASA/NOAA program to provide an improved source of meteorological data for weather forecasting. The initiative for starting the project came from a recognition that much of our weather originates in the data sparse areas of the tropics and Southern Hemisphere. It was further recognized that these areas are frequently crossed by many of the modern, wide-body jet aircraft of the B-747, DC-10 type. These aircraft contain navigation and data systems capable of providing the following data: latitude, longitude, altitude, wind speed, wind direction, and outside air temperature. The ASDAR system consists of a data acquisition and control unit to acquire, store, and format this data; a transmitter to relay the formatted data via satellite to the ground; and a clock to time the data sampling and transmission periods. In cooperation with the National Oceanic and Atmospheric Administration (NOAA) the data is relayed to the ground via their Geostationary Operational Environmental Satellite (GOES) series and then to the National Meteorological Center (NMC) to aid in weather forecasting.
    • The American Satellite Transmission System

      Cacciamani, Eugene; Garner, William; American Satellite Corporation (International Foundation for Telemetering, 1978-11)
      In 1979, American Satellite Corporation will be the first on-line completely all-digital communications carrier. This will be accomplished when American Satellite Corporation's major trunking earth terminals are converted to operate TDMA at data rates up to 64 Mbps.
    • Analog- Digital LSI on the E⁺ᵗ Curve

      Constant, R. N.; Lekven, C. M.; The Aerospace Corporation (International Foundation for Telemetering, 1978-11)
      The title of this paper was selected to indicate that large scale integration (LSI) of analog (linear), digital and combined monolithic analog and digital (A & D) circuits for telecommunication systems is progressing at an exponential rate. As is the case with exponential functions, near term (i.e., when t is small) increases are rather modest, but, once started, the function grows rapidly. This is the case of A & D LSI: it is just starting to take hold, and impressive gains are expected in the future. The purpose of this paper is to explore, from the system point of view, some of the recent technology developments that have taken place and that are expected to impact the design of future telemetry, communication and sensor equipment.
    • An Analysis of a Tandem Queueing System for Flow Control in Computer Networks

      Chu, W. W.; Faylolle, G.; Hibbits, D.; University of California, Los Angeles; I.R.I.A. (International Foundation for Telemetering, 1978-11)
      A tandem queueing system with constant service times and threshold control is modeled and analyzed in this paper. The input to the first queue is controlled by the buffer occupancy of the second queue. When the second queue has more than No customers, the input to the first queue will be rejected. The input to the second queue consists of the output from the first queue and an external input which is assumed to be Poisson distributed. The behavior of such a queueing system is analyzed and portrayed in graphs. The threshold control rejects input traffic to the first queue and avoids congestion at the second queue. As a result, the delay for an arrival to be serviced by both of the queues is much lower than the case without threshold control. As N₀ increases, the system behavior approaches the case of the system without threshold control. Such a queueing model is motivated by congestion control in a computer network. An example is given to illustrate the applications.
    • Appendix: Sixteenth Annual Report of the Telemetering Standards Coordination Committee

      Jeske, Harold (International Foundation for Telemetering, 1978-11)
    • Application of a Technology: The Case of Fiber Optics and MIL-STD-1553

      Meador, Terrance A.; Naval Ocean Systems Center (International Foundation for Telemetering, 1978-11)
      Guidelines for the utilization of fiber optics transmission technology in the design of a standardized aircraft multiplex system interconnect have been difficult to establish. MILSTD-1553 is imprecise in the separation of transmission and operational functions with the result that the substitution of fiber optics for wire transmission specifications is impractical without redefinition of the 1553 word formats and data bus architecture.
    • Application of Microprocessors to Spacecraft Synthetic Aperture Radar Processing

      Arens, Wayne E.; California Institute of Technology (International Foundation for Telemetering, 1978-11)
      A ground-based digital synthetic aperture radar (SAR) processor capable of correlating images from raw spacecraft data at real-time rates is currently under development. The processor design requirements are particularly formidable due to (1) range migration effects resulting from planetary curvature and rotation, (2) antenna beam pointing errors, and (3) variation of the doppler reference function with changing orbital parameters. Based upon the current effort, this paper describes a candidate real-time on-board SAR processing implementation approach that might evolve for future spacecraft applications. Key features include the use of custom large scale integration (LSI) charge-coupled device (CCD) technology to accomplish the correlation functions and microprocessor technology to effect control.
    • Applied Telecommunication System [FATEC] Using Microprocessor for Versatile Data Acquisition and Supervisory Control

      Okamoto, Takashi; Atsuya, Kin-ichi; Higeta, Tsukumo; Kakehi, Gen; Iizuka, Masaru (International Foundation for Telemetering, 1978-11)
      It is required recently for data acquisition and supervisory system to provide transparent transmission of bit and message informations by packet or non-packet transmission method, and to provide various kinds of interface to I/O. In order to fulfill these requirements we have developed the new system called FATEC(Fujitsu Applied Telecommunication System) using microprocessor and bus technology.
    • Bandwidth Compression of Multispectral Satellite Imagery

      Habibi, A.; TRW Defense and Space Systems Group (International Foundation for Telemetering, 1978-11)
    • Bounded Error Data Compression at Constant Rate

      Gonsalves, Robert A.; Evans, Norman E.; Shea, Alicia; EIKONIX Corporation (International Foundation for Telemetering, 1978-11)
      We present a technique to compress M-bit data to N-bit data with a bounded error between the original and de-compressed data. The bounded error is established by quantizing the error signal of DPCM and by entropy encoding the quantized error. The fixed data rate is maintained by non-linear adaptation of the quantization interval on an intermittent basis. Examples of image data compression are given.
    • Bubble Memories for Spacecraft Mass Storage Status and Potential

      Murray, Glenn W.; Rockwell International (International Foundation for Telemetering, 1978-11)
      A combination of solid state technology, high storage density and nonvolatility makes Bubble Memory Technology an attractive option for spacecraft system designers. It has the potential for not only replacing conventional spaceborne mass store media such as tape but also the flexibility to be configured into mass store system resembling disks providing the designer with memory organizations for space applications not previously available. The current state of this technology is assessed in terms of memory element, memory element packaging and system design with special attention to those aspects particularly relevant to space applications. Future developments in the technology and their impact on the capability and application are also considered.
    • A Class of Programmable Satellite Receivers

      Klare, Stephen W.; Motorola, Inc. (International Foundation for Telemetering, 1978-11)
      The currently developed theory of optimal demodulation and synchronization systems for digital data has been applied to the design of a class of programmable satellite receivers. The primary purpose is to provide flexibility in application through digital control of the important functions of the receiver. This permits the acquisition and demodulation of medium to very low data rates in widely varying communications environments and over a broad range of modulation schemes. The receiver peripherals are controlled by a digital processor which can accept external commands to reconfigure to any of a preprogrammed set of algorithms.
    • Coherent Demodulation for Orthogonal Sideband and Carrier Tracking

      Udalov, Sergei; Axiomatix (International Foundation for Telemetering, 1978-11)
      A demodulation technique which permits simultaneous coherent and orthogonal tracking of a suppressed carrier and of the associated sidebands is described. The performance of a demodulator based on such a technique is defined for a general case and for a specific case of two-channel FM multiplexing. Experimental data supporting the analysis of the FM multiplexing mode of the demodulator is presented and discussed.
    • A Coherent Receiver for QPSK and SQPSK Signals

      Alem, W. K.; Weber, C. L.; Axiomatix; University of Southern California (International Foundation for Telemetering, 1978-11)
      A demod-remod type of coherent tracking loop for conventional QPSK and staggered QPSK (SQPSK) is presented. The phase detector characteristic (S-curve) is determined. The effects of power unbalance and arm gain unbalance on the S-curve are presented. The steady state rms phase error is shown as a function of the signal-to-noise ratio at the output of the arm filters.
    • A Comparison Between Coded MPSK and MFSK Systems

      Biederman, L.; Huang, T. C.; LinCom Corporation (International Foundation for Telemetering, 1978-11)
      The performance of two coded communication systems is compared. The first one is obtained when the system modulation is coherent PSK. The second system results when the modulation is noncoherent FSK. The coding parameter adopted to evaluate the system performance is the cut-off rate. A second parameter called coded throughput is derived from the cut-off rate and utilized to effectively compare the performance of the two coded systems under consideration.