• Bandwidth Compression of Multispectral Satellite Imagery

      Habibi, A.; TRW Defense and Space Systems Group (International Foundation for Telemetering, 1978-11)
    • High Performance Circulators, Isolators and Electronic Waveguide Switches

      Piotrowski, Wieslaw S.; TRW Defense and Space Systems Group (International Foundation for Telemetering, 1978-11)
      This paper presents the results of a most recent high technology development program that has led to significant state-of-the-art advances in the design and development of circulators, isolators and electronic waveguide switches at microwave and millimeter wave frequencies. These components are constructed by the use of an analytical design procedure. They are characterized by excellent electrical and environmental performance and feature a simple mechanical configuration, which results in significantly reduced prices. These units are presently commercially available from Aertech Industries, Sunnyvale, California, a TRW subsidiary.
    • Performance Evaluation of Communication Channels by Computer Simulation

      Poza, H. B.; TRW Defense and Space Systems Group (International Foundation for Telemetering, 1978-11)
      A computer simulation model capable of aiding in the design and predicting the performance of complex end-to-end communication systems is described in this paper. The model is used to choose the optimal modulation scheme under certain communication channel constraints, define the signal distortion characteristics introduced by realizable channel components and select the demodulator/bit synchronizer designs for minimization of bit error rate. A parameter sensitivity analysis is conducted to demonstrate the usefulness of the model in evaluating the effect of different signal distortion phenomena on overall link performance.
    • Performance of Bandlimited and Hardlimited PSK Signals

      Rey, R. D.; TRW Defense and Space Systems Group (International Foundation for Telemetering, 1978-11)
      Transmission of a signal through a channel, such as a satellite communication channel, results in distortion of the signal due to bandlimiting in the individual channels and hardlimiting. The purpose of this paper is to study the effects that channel distortion due to filtering and hardlimiting have on the performance of BPSK and QPSK. The results will be used to determine the maximum bit rate which can be transmitted through a channel having a particular bandwidth with a specified limit in degradation of performance.
    • Shallow Bulk Acoustic Wave Devices - A New Type of Acoustic Wave Device for Communication Systems

      Lau, K. F.; Yen, K. H.; Kagiwada, R. S.; TRW Defense and Space Systems Group (International Foundation for Telemetering, 1978-11)
      This paper reviews the present status of a new type of acoustic wave device which has many potential applications. These devices are called Shallow Bulk Acoustic Wave (SBAW) devices because the signal propagates just below the surface of the piezoelectric substrate. These waves can be efficiently generated and detected by interdigital transducer and fabricated by techniques similar to those of surface acoustic wave (SAW) devices. These planar devices have been configured into bandpass filters, delay lines, oscillators and resonators. Because they utilize bulk waves rather than surface waves, SBAW devices possess many advantages over SAW devices. They have a higher frequency of operation, lower loss, better temperature stability, and, most likely, better aging characteristics. With these advantages, SBAW devices promise to replace both bulk crystals and SAW devices in many future communication systems.
    • Space Shuttle Orbiter PN Code Synchronization

      Houston, Sam W.; TRW Defense and Space Systems Group (International Foundation for Telemetering, 1978-11)
      The S-band Communications link to the Space Shuttle Orbiter from ground stations via TDRSS are transmitted spread spectrum to reduce the incident power flux density on the Earth's surface. This paper describes the requisite spread spectrum processing onboard Shuttle.
    • TDRSS - User Satellite Acquisition and Tracking

      Franklin, S. B.; TRW Defense and Space Systems Group (International Foundation for Telemetering, 1978-11)
      The Tracking and Data Relay Satellite System (TDRSS) will provide communications and tracking services to the Space Shuttle and most other NASA missions of the 1980's. Relay services are provided between NASA's near earth satellites and a ground terminal at White Sands, N.M. via synchronous Tracking and Data Relay Satellites. Establishing and maintaining the communications links is a complex task which includes spatial, signal and data acquisition involving crosslinks between the TDRS and NASA's user satellites. Concepts and capabilities are presented for antenna acquisition, and for PN code and carrier acquisition. Total acquisition times, including bit synchronizer and decoder acquisition are also provided.
    • TDRSS Multiple Access Receiving Phased Array System

      DuPree, J. E.; TRW Defense and Space Systems Group (International Foundation for Telemetering, 1978-11)
      A 30-element phased array, with remote beamforming and multiple access signal design, is the basis for a new multiple access concept to be used by the Tracking and Data Relay Satellite System (TDRSS). System tradeoffs evolved a control and calibration concept which parallels modern estimation theory in dynamic systems and reduces the complexity of adaptive control while maintaining the necessary accuracy. A system dynamic model propagates "open loop" estimates of optimal weight vectors based on user satellite ephemerides derived from tracking data. A sampled-data closed loop adaptive control system periodically updates the beam-steering vector to eliminate parameter drifts and modeling errors, and to maintain the weight vector near optimum. The concept is primarily useful in the specified noninterference environment, though some nulling capability is possible.
    • 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.