• Engineering of a Multifunction Spread Spectrum System

      Winterkorn, John H.; The Aerospace Corporation (International Foundation for Telemetering, 1978-11)
      In the past ten years there have been dramatic strides in the spread spectrum communications system area. The knowledge of spread spectrum systems has progressed from a fragmented understanding of the techniques and their characteristics to the point where spread spectrum communication techniques are well documented and their characteristics are well understood. Thus, spread spectrum has progressed from analytical investigation into practical application. This presentation will provide a brief tutorial on spread spectrum techniques in the RF, modulation detection, and coding areas. The characteristics of these techniques will be addressed and related to specific communication functions. The presentation will address the application of spread spectrum techniques to a communication system design and will emphasize the suitability of spread spectrum for multiple applications in a given system. Specific examples of multiple spread spectrum usage will be given and a generalized approach to spread spectrum engineering will be presented. The application of this system approach to spread spectrum engineering results in spread spectrum taking on functions beyond its primary purpose of existence and becoming an integral part of a communication system rather than being an add-on, necessary but undesirable, appendage.
    • Considerations in AJ System Development, Operation and Definitions

      Goldman, H. B.; Hughes Aircraft Company (International Foundation for Telemetering, 1978-11)
      The conventional communication system is designed to work over a worst-case propagation environment with sufficient performance so that the probability of mission success is cost-effectively achieved. Conventional systems have been in a state of evolution and refinement since the early part of the 20th century. Their anomalies are well known. The jam-resistant communications system, however, with additional emphasis on low probability of intercept and exploitation (LPI, LPE) present a whole new list of uncertainties that affect deployment, operation and definitions of what AJ and LPI are in terms of performance against propagation anomalies, the jammer and the intercept system threat.
    • Appendix: Sixteenth Annual Report of the Telemetering Standards Coordination Committee

      Jeske, Harold (International Foundation for Telemetering, 1978-11)
    • Optimum Quantization for Minimum Distortion

      Caprio, James R.; Westin, Nancy; Esposito, John; Comptek Research, Inc.; State University of N.Y. at Buffalo (International Foundation for Telemetering, 1978-11)
      This paper treats the problem of optimal selection of data quantization levels for minimum error. No assumptions are made regarding the underlying statistics of the process to be quantized. A finite precursor sample of the data is analyzed to infer the underlying distribution. Selection of optimum quantization levels can then be related to the generation of an optimum histogram for the data record. The optimum histogram is obtained by a dynamic programming approach for both least mean square error and minimum Chebychev error criteria. Transmitted data can then be quantized according to levels specified by the histogram. The process can be repeated periodically either with a new data sample, if the underlying process is nonstationary, or performed on the accumulated record in the stationary case.
    • 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.
    • A SEASAT Synthetic Aperture Radar Preprocessor (SARP)

      Waltz, Edward L.; Bendix Aerospace Systems Division (International Foundation for Telemetering, 1978-11)
      A Synthetic Aperture Radar Preprocessor (SARP) for the SEASAT radar is described. The SARP system permits playback of Synthetic Aperture Radar (SAR) data for digital processing into ocean imagery. The system includes a High Data Rate Recorder, SAR Digital Preprocessing (SDP), array processor, mass storage disc, and host computer. Data tapes are played back at reduced rates and the SDP performs the functions of frame synchronization, decommutation of time and status data, presummation of adjacent azimuth returns and correction of gain as a function of range. The data are formatted into presummed range returns and are transferred to the array processor for buffering and subsequent storage on the mass disc. This preprocessing operation loads a 100 x 100 km swath of data on the disc for subsequent range and azimuth correlation to convert the SAR data to imagery. The SAR Data Preprocessor equipment is described and the implementation of the 35 Mbps frame synchronizer and presum arithmetic logic are detailed. A SAR Test Pattern Generator for simulation of SAR and other image data formats is also described. The test generator permits simulation of a wide range of digital data formats (including NASA and IRIG standards) and includes a programmable data pattern capability.
    • Bandwidth Compression of Multispectral Satellite Imagery

      Habibi, A.; TRW Defense and Space Systems Group (International Foundation for Telemetering, 1978-11)
    • Fast Fourier Transform Algorithm Formulation

      Thong, Tran; General Electric Company (International Foundation for Telemetering, 1978-11)
      A new unified formulation of the fast Fourier transform based on the unwrapping of a multi-dimensional array is presented. The decimation in time FFT algorithms is treated in detail. The decimation in frequency algorithms is then discussed.
    • 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.
    • Quantization for Signal Detection and Representation

      Kassam, Saleem A.; University of Pennsylvania (International Foundation for Telemetering, 1978-11)
      For digital representation of analog data the minimum mean-squared-error criterion is commonly used as a criterion for the basis of optimum quantizer design. In this paper we show that in some situations measures other than the minimum mean-squared-error may be more appropriate. For the signal representation problem, it is shown that the mean-absolute-error criterion has theoretical justification, as again for some signal detection problems it is shown that the mean-squared-error criterion is not the most appropriate criterion.
    • A Flexible User Oriented Approach to Communications Systems Simulation

      Fashano, M.; Austin, M. C.; Hughes Aircraft Company (International Foundation for Telemetering, 1978-11)
      An advanced software/hardware computer system developed for the simulation of communications systems is described. This user oriented system allows for flexible and efficient modeling and simulation of complex communications systems. Excellent agreement between simulation and measured results has consistently valididated the simulation approach.
    • Video Encoding for the Space Shuttle

      Habibi, A.; Batson, B. H.; TRW Defense and Space Systems Group; NASA Lyndon B. Johnson Space Center (International Foundation for Telemetering, 1978-11)
      The Space Shuttle will initially be using a field sequential color television system but it is possible that an NTSC color TV system may be used for future missions. In addition to downlink color TV transmission via analog FM links, the Shuttle will use a high resolution slow-scan monochrome system for uplink transmission of text and graphics information. This paper discusses the characteristics of the Shuttle video systems, and evaluates digitization and/or bandwidth compression techniques for the various links. The more attrative techniques for the downlink video are based on a two-dimensional DPCM encoder that utilizes temporal and spectral as well as the spatial correlation of the color TV imagery. An appropriate technique for distortion-free coding of the uplink system utilizes two-dimensional HCK codes.
    • Experimental 2 GBPS MM Wave System and 4 GBPS QASK Modulator

      Horwood, D. F.; Luke, R. T.; Lee, G. E.; Des Brisay, G. S., Jr.; Hughes Aircraft Company (International Foundation for Telemetering, 1978-11)
      A 2 GBPS QPSK modulator and demodulator were developed and BER performance was evaluated over a millimeter wave data channel. The error rate measurements taken with the breadboard equipment showed system performance to be less than 2 dB from theoretical at an error rate of 10⁻⁵. Additionally, a second QPSK modulator was constructed and combined with the first to generate 4 GBPS QASK data for future evaluation.
    • The Impact of LSI on Telemetry Systems

      Finn, W. J.; Karwoski, R. J.; TRW LSI Products (International Foundation for Telemetering, 1978-11)
      Any system which measures, transmits over a distance, receives, and processes signals can be defined as a telemetry system. Video transmission systems, satellite communications systems wideband data links, and TDM/FDM transmultiplexers all have one thing in common: an increasing need for high-speed digital signal processing. This paper is intended to serve as an introduction to the application of LSI to telemetric signal processors.
    • Solid State Microwave Power Amplifiers - An Overview

      Lewinter, S. W.; The Aerospace Corporation (International Foundation for Telemetering, 1978-11)
      This paper summarizes results that have been achieved with various types of microwave solid state power amplifying devices and presents some projections of advances that can be expected within approximately a five year period. The frequency band surveyed extends from 1 to 100 GHz. The emphasis is on CW or high duty cycle pulse applications, where long life is of great importance, such as in a satellite communication system. The types of devices considered include the gallium arsenide field-effect transistor (GaAs FET), IMPATT diodes, bipolar transistors, Gunn diodes, TRAPATT diodes and electron bombarded semiconductor (EBS) devices. An overview of the technology of microwave power combiners is also included.
    • MNOS Spacecraft Recorders

      Brewer, J. E.; Westinghouse Electric Corporation (International Foundation for Telemetering, 1978-11)
      MNOS memory components are well suited for use in spacecraft recorders. Recorder design considerations and MNOS chip requirements are reviewed, and projections for 10⁸ and 10⁹ bit recorders are presented.
    • SEASAT-A: An Experiment in End-to-End Information System Design

      MacMedan, Mervyn L.; NASA Jet Propulsion Laboratory (International Foundation for Telemetering, 1978-11)
      The SEASAT-A ocean dynamics monitoring satellite was designed with a keen awareness of the problems of handling huge volumes of data from an Earth-orbiting applications mission. An "End-to-End" approach to the entire information system was adopted very early in the life of the Project. Some innovations introduced include the provision of a "Packet Telemetry" system which is very similar to the NEEDS program objectives, and the incorporation of an adjustable satellite clock which directly time-tags the sensor data in GMT. This paper will review the mission and information system performance, and will summarize lessons learned from the experiment in system design.
    • Wafer Integrated Semiconductor Mass Memory

      Geiderman, William A.; Solomon, Allen L.; McDonnell Douglas Corporation (International Foundation for Telemetering, 1978-11)
      This paper describes a light-weight, small-volume, low-power semiconductor mass memory which will provide high reliability operation in a variety of environments. The memory employs two new technologies: adaptive wafer scale integration where large numbers of memory arrays are interconnected on the wafer substrate using nonvolatile latching circuits; and a nonvolatile charge-coupled device memory element. The nonvolatile charge-coupled devices and peripheral circuitry are fabricated on a single silicon substrate using metal-nitride-oxide-semiconductor (MNOS) transistor structures. The adaptive latching circuits enable malfunctioning arrays to be replaced in situ by spare arrays which are available on the wafer substrate through the use of error detection/ correction circuitry. The paper also describes a specification for a spaceborne mass memory system including peripheral circuits. A memory system with a gigabit data storage capacity (total active storage elements = 1.2 gigabits can be fabricated within 0.6 cubic feet at an estimated weight of 26 pounds.
    • Subcarrier Phase Recovery Performance in Bent-Pipe Mode of Shuttle Data Transmission

      McKenzie, Teresa M.; Braun, W. R.; LinCom Corporation (International Foundation for Telemetering, 1978-11)
      The subcarrier phase recovery is analyzed for the bent-pipe mode of Space Shuttle detached-payload data transmission on the Tracking and Data Relay Satellite System (TDRSS) Ku-band return link. The high-power component of the subcarrier modulation is unrestored payload data, either at baseband or modulating another subcarrier. At the receiver a Costas loop recovers the subcarrier phase. To analyze its performance in the baseband case, we obtain the loop S-curve, the power spectral density of the equivalent noise process, and the loop phase error variance.
    • Space Shuttle Payload Communication Links

      Springett, James C.; Udalov, Sergei (International Foundation for Telemetering, 1978-11)
      One mission of the Shuttle is to place payloads into Earth orbit or on escape trajectories and to recover payloads from Earth orbit. In order to properly deploy and retrieve such payloads, operational and diagnostic communications must take place between the payloads and the Shuttle. The results of such communications, in the form of tracking, commands, and telemetry, will be interpreted both aboard the Shuttle and on the ground. To accommodate a diverse set of payloads for both NASA and DOD programs, multimode avionic equipment dedicated to payload communications is being installed aboard the Shuttle. This equipment, operating at RF and baseband and providing capability for digital and analog signal forms, will furnish all required capabilities to communicate with both attached and detached payloads.