• MILITARY COMMUNICATION SATELLITES

      Wall, Virgil W.; The Aerospace Corporation (International Foundation for Telemetering, 1973-10)
    • A MULTI-PURPOSE, DUAL-CHANNEL MODEM FOR C/No THRESHOLD

      Baghdady, Elie J.; Info Systems (International Foundation for Telemetering, 1973-10)
      A description is given of a newly developed modem based on the synthesis of a constant-envelope quadra-phase signal with dual-channel frequencydivision multiplexing of analogvoice with data, data with data, time code With data, ranging signal with d:Ata, etc. The technique is capable of providing low-threshold operation down to carrier power-to-(noice power density) ratios, about 40 db, and includes a built-in, on-line measurement and display of the C/N(o) for quantitative performance monitoring purposes.
    • MULTIMEGABIT OPERATION MULTIPLEXER SYSTEM

      Giri, Ronald R.; Maxwell, Marvin S.; Radiation; Goddard Space Flight Center (International Foundation for Telemetering, 1973-10)
      The Multimegabit Operation Multiplexer System (MOMS) is a high data rate PCM telemetry unit capable of sampling and encoding 60 scanning radiometer and 4 vidicon channels at 250 kilosamples/second and 5 megasamples/second, respectively. This sampling capacity plus the 7-bit quantization requires a total throughput rate of 40 megasamples/second and 280 megabits/second. To produce these rates efficiently, the system was divided into a pair of identical 140-megabit blocks. A low-power 20-MHz analog multiplexer and analog-to-digital converter were developed together with a video sample-and-hold that features an aperture time error of less than 50 picoseconds. Breadboard testing of these basic building blocks confirmed the design prediction that the total system would consume 27 watts of power. Two 140-megabit output ports are suitable for quadraphase modulation.
    • MULTISTATE ANALOG AND DIGITAL INTEGRATED CIRCUITS

      Abraham, George; US Naval Research Laboratory (International Foundation for Telemetering, 1973-10)
      Several independent physical phenomena in unipolar and bipolar semiconductor pn junction devices and integrated structures lead to voltage and current-controlled negative resistance without the use of external feedback. These include avalanche breakdown, quantum mechanical tunneling, and minority carrier storage. Two complementary types of negative resistances may be utilized as a basis for generating multistable energy levels. The number of stable states and their relative spacings can be readily varied. Without negative resistance interaction, M+1 stable states can be generated where M is the number of negative resistance devices involved. With negative resistance interactions, additional multistability occurs, resulting in a total number of (M+1) + (M-1)!stable states. S-S, N-N, and S-N interactions are analyzed. In the latter case, complementary negative resistances can be made to annihilate each other. Multistate tunnel and avalanche negative resistances have been made to occur in single devices resulting in tristable, quadristable and higher order energy levels. Variable radix counters, oscillators, frequency dividers, and high density memory elements have been fabricated both as hybrid and monolithic integrated circuits.
    • 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.