• THE NEED TO MEASURE MAN-MADE RADIATION FROM ORBIT FOR SPECTRUM MANAGEMENT

      Eckerman, Jerome; Wolff, Edward A.; National Aeronautics and Space Administration (International Foundation for Telemetering, 1973-10)
    • A NEW ERA IN WORLDWIDE TACTICAL COMMUNICATIONS

      Reid, Charles E. Jr; Naval Electronic Systems Command (International Foundation for Telemetering, 1973-10)
      The Fleet Satellite Communication System (FLEETSATCOM) now under development will provide the first U. S. military satellites designed from the start as operational transponders for tactical communications with and among mobile users. FLEETSATCOM is a logical outgrowth of earlier experimental projects, principally the Tactical Satellite Communication (TACSATCOM) project of the late 1960’s. When the globe-girdling system goes operational in calendar year 1976 it will quite literally revolutionize both Air Force and Navy tactical communications by providing availability and reliability of over-the-horizon communications that can never be matched by conventional high-frequency circuits.
    • NEW MAJORITY-LOGIC DECODABLE CODES

      Chen, C.L. (International Foundation for Telemetering, 1973-10)
      A method of the construction of majority-logic decodable codes is presented. Many of the codes constructed are more efficient than any other comparable majority-logic decodable codes previously known.
    • ON DETERMINATION OF OPTIMAL ACCUMULATION TIME IN PARTICLE FLUX REGISTRATION

      Babkin, V. F.; Institute for Space Research (International Foundation for Telemetering, 1973-10)
      Poisson particle flux is considered which intensity is a random process. The equations are presented for the construction of the intensity realization estimate corresponding to the minimum of a mean-square reconstruction error. The condition is derived the filfulment of which assures the existence of the optimal accumulation time minimising the reconstruction error. The calculation results are given to illustrate the dependence of a mean-square reconstruction error on the accumulation time.
    • Optran® AN INFRARED LED TRANSCEIVER FOR DATA COMMUNICATIONS

      Meyer, Andrew W.; Harting, Stephen W.; National Aeronautics and Space Administration (International Foundation for Telemetering, 1973-10)
      The following discussion reviews operating experience with a non-coherent infrared (IR) optical data link at several installations in the United States. Optran is a commercial digital data link, manufactured by Computer Transmission Corporation, for computer-to-computer or computer-to-terminal data transfer applications. It uses a nonlasing gallium arsenide diode as the transmitter and a silicon diode as the receiver. Simple optics collimate the transmitter output and focus the captured receive energy on the receiver diode. A digital interface unit at each terminal end presents a standard interface to business equipment and encodes/decodes data from the optical head.
    • A PCM DATA SEQUENCE CONTROLLER

      Sandia Laboratories; Johnson, Charles S. (International Foundation for Telemetering, 1973-10)
      The PCM Data Sequence Controller described in this paper is used to interface a memory-controlled PCM encoder with a plated wire memory to form a unique digital data compression and storage system. The memory-controlled PCM encoder is used to select formats and convert input analog data channels into a PCM bit stream which is both transmitted and stored in a plated wire memory. The encoder is also used to retrieve information from the plated wire memory and retransmit it. The system provides both temporary and permanent data storage for the telemetering of data in a severe environment.
    • PERFORMANCE OF A 350-Mb/s ADAPTIVE EQUALIZER

      Ryan, Carl R.; Stilwell, James H.; Motorola Inc. (International Foundation for Telemetering, 1973-10)
      This paper applies baseband adaptive equalization techniques to rf multipath and transmitter/receiver distortions. Included are test results comparing 350-Mb/s adaptive equalized and unequalized receivers. These comparisons are made with distortion typically encountered in a high data-rate line-of-sight microwave system such as demodulator quadrature errors, demodulator phase offset errors, and moderate rf multipath distortion. The design and construction techniques are also illustrated.
    • PLANETARY PROGRAM DATA SYSTEMS STANDARDS

      Glahn, Earl W.; Planatary Programs Data Systems Working Group (International Foundation for Telemetering, 1973-10)
    • PRINCIPLES AND HEAD CHARACTERISTICS IN VHF RECORDING

      Krey, K. H.; Lieberman, A. G.; Harry Diamond Laboratories; University of MD (International Foundation for Telemetering, 1973-10)
      Concepts of VHF analog magnetic recording are discussed; problem areas are reviewed; and solutions are outlined. Attention is drawn to the conductive-gap-spacer recording head. The unique field contours of this recording head with Alfesil pole faces are analyzed in relation to the recording of very short wavelengths. The field gradients of the unloaded head are computed for various conditions such as maximum magnetization depths, positions in the tape coating, and gap lengths. Comparison of the driven-gap-spacer head using Alfesil pole faces with the ferrite driven-gap-spacer head and the conventional ring-core head shows the Alfesil type to be the most effective for a-c bias VHF recording at very short wavelengths. Problems associated with short-wavelength recording and reproduction are reviewed. In spite of good short-wavelengths capabilities of the Alfesil head, the requirement for a high head-to-tape speed continues to be mandatory to minimize wavelength reproduction losses.
    • A PROGRAMMABLE SAMPLING FORMAT TELEMETRY SYSTEM

      Peterson, Max B.; Johns Hopkins University (International Foundation for Telemetering, 1973-10)
      This paper describes the programmable sampling format telemetry system to be used by the near-earth Small Astronomy Satellite-C (SAS-C) and possible future SAS missions. The concept of the programmable sampling format is introduced and the features of the system are illustrated by an example. The SAS-C telemetry system is described at the block diagram level and redundancy of the system is discussed briefly.
    • RCC TELEMETRY STANDARDS

      Reynolds, R. Stanton; Range Commanders Council (RCC) Telemetry Group (International Foundation for Telemetering, 1973-10)
    • A REAL-TIME HADAMARD TRANSFORM SYSTEM FOR SPECIAL AND TEMPORAL REDUNDANCY REDUCTION IN TELEVISION

      Noble, S. C.; Knauer, S. C.; National Aeronautics and Space Administration (International Foundation for Telemetering, 1973-10)
      A digital Hadamard transform system has been developed for the real-time compression of standard NTSC television signals. The system digitizes the video signals and subdivides four successive frames of data into suppictures of sixty-four picture elements. The subpictures are cubes four elements on a side, in horizontal, vertical and temporal directions. Subpictures are transformed and processed to reduce special and temporal redundancy. Implementation and performance results of the system will be described and discussed.
    • RECONSTRUCTION OF DISTORTED SAMPLES IN DIGITAL TELEMETRY

      Berezin, V. I.; Sviridenko, V. A.; Trofimov, A. M.; Shtarkov, Yu. M. (International Foundation for Telemetering, 1973-10)
      The problem of processing of an analog-digital message, that is transmitted via the noise channel is digital form, is considered. A simple algorithm of correction of distorted samples is proposed with the use of one symbol for even parity checking and linear interpolation. The expression for a resulting mean-square error is obtained, that allows to evaluate the influence of noises in a channel. Possible generalizations of the formulated problem are presented.
    • THE REDUNDANCY OF A SIMPLE SYNCHRONIZATION METHOD FOR VARIABLE LENGTH CODES

      Shtarkov, Yu. M.; Academy of Sciences of the USSR (International Foundation for Telemetering, 1973-10)
      Prefix insertion prior to the coded representation of every fixed length block of data provides a simple synchronization method for variable length coding. Unlike fixed length coding where the prefix appears with a set period, the appearance time of each prefix word in the variable length coded representation is a random variable. At the receiver a synchronization decision is made whenever a pattern within a threshold Hamming distance of the prefix is received. In this paper an expression is found for small synchronization error probabilities. This egression depends on the coded block length only through its average value L. The optimal value for the recognition threshold is found. The necessary and sufficient condition for an arbitrarily small synchronization error probability is shown to be that the prefix length grows as log L. The results are discussed from the viewpoint of data compression and source encoding.
    • RELAY TECHNIQUES FOR MOBILE SERVICES

      Vandenkerckhove, J.; ESRO/ESTEC (International Foundation for Telemetering, 1973-10)
      Dr. Vandenkerckhove will discuss system considerations involved in providing communications services to aeronautical and maritime users via Synchronous Relay Satellite.
    • A REVIEW OF MULTIPLE AMPLITUDE-PHASE DIGITAL SIGNALS

      Smith, Joel G.; California Institute of Technology (International Foundation for Telemetering, 1973-10)
      This paper reviews the data rate, error rate, and signal-to-noise ratio relationship for various uncoded M-ary digital amplitude modulation (AM), phase modulation (PM), and combined AM-PM systems. These signal systems have the common virtue that expanding the number of possible signals to be transmitted increases the data rate but not the bandwidth. The increased data rate generally requires an increased signal-to-noise ratio to maintain constant error probability performance. Thus, these systems use power to conserve bandwidth. A general treatment of the error rate of M-ary digital AM-PM permits development of a simple yet accurate expression which approximates the increase in average signal-to-noise ratio (over that of binary phase shift keying) required for constant error performance. This equation provides insight into why arrays differ in their signal-to-noise ratio requirements.
    • RFI ANALYSIS APPLIED TO THE TDRSS SYSTEM

      Jenny, J.A.; ESL Incorporated (International Foundation for Telemetering, 1973-10)
      The effect of radio frequency interference (RFI) on the proposed Tracking and Data Relay Satellite System (TDRSS) was assessed. The method of assessing RFI was to create a discrete emitter listing containing all the required parameters of transmitters in the applicable VHF and UHF frequency bands. The transmitter and spacecraft receiver characteristics were used to calculate the RFI contribution due to each emitter. The individual contributions were summed to obtain the total impact in the operational bandwidth. Using an as yet incomplete enitter base, we have concluded that the 136-137 MHz band should be used by TDRS rather than the whole 136-138 MHz band because of the higher interference levels in the 137-138 MHz band. Even when restricting the link to 136 to 137 MHz, the existing link design is marginal and it is recommended that interference reduction units, such as the Adaptive Digital Filter, be incorporated in the TDRS ground station. RFI is less of a problem in the 400.5 to 401.5 MHz band and can probably be handled by restricting command transmissions to low RFI areas or if that is not acceptable, by using simple automatic notch filters to notch out the few interferers present.
    • SATELLITE-AIRCRAFT DIGITAL TRANSMISSION EXPERIMENT RESULTS AT L-BAND

      Wilson, Stephen G.; Boeing Commercial Airplane Company (International Foundation for Telemetering, 1973-10)
      Results of an experiment involving the synchronous satellite relay of digital information at L-band between a ground station and a jet aircraft are described. Specific tests studied the performance of PSK signalling in conjunction with three distinct detection strategies for both the classical additive noise channels and the composite multipath channel (direct signal plus multipath). Tests were conducted at various signalto-noise ratios and direct signal-to-multipath ratios. Reasonable agreements with available non-fading and Rician fading channel theory is shown. Implications for the operational aeronautical satellite case are discussed.
    • A SHOCK HARDENED PCM SYSTEM WITH DATA STORAGE

      Barnes, D. E.; Sandia Laboratories (International Foundation for Telemetering, 1973-10)
      A miniature shock hardened PCM system with data storage capability has been developed by Sandia Laboratories for use in test where RF transmission either difficult or impossible. The PCM has 16 channel input capacity and encodes the data with 6 bit accuracy. The data rate is selectable from 1k bit per second to 250 k bit per second. The encoder has been harbarized and packaged in a volume of less than 4 cubic inches. The data storage is selected in 6 k bit increments with a maximum storage of 600 k bits. Typical applications involving earth and water penetrating are described.
    • A SHORT RANGE 15 MEGABIT/S LED COMMUNICATOR

      Dworkin, L. U.; Coryell, L.; USAECOM (International Foundation for Telemetering, 1973-10)
      The design, development, and testing of a short range (distances up to 100 ft) data communications equipment that utilizes a GaAs light emitting diode (LED) source is discussed. Data rates of 15 Mb/s are accommodated by a transmission terminal which consists of a line of sight (LOS) atmospheric portion and a fiber optic link. The system has an all weather capability, is relatively inexpensive and is intended for tactical military applications. This is the first attempt at developing a wideband optical communicator that has a similtaneous LOS and cable capability often needed in a tactical military environment.