• Supervisory Control and Telemetry Using Emulation-Type Microcomputer

      Yanaka, Masao; Takahashi, Masahiro; Kobayashi, Kazuhiko; Hasegawa, Syuzi; Hitachi Ltd. (International Foundation for Telemetering, 1976-09)
      An advanced Supervisory Control and Telemetry system has been developed to meet the diversified requirements from the widening range of application fields such as utility industries, highways and railways. The transmission procedure employed is Cyclic Digital Transmission (CDT)a procedure most widely adopted in Japan, especially in the electric power control field. The master station possesses the capability of accomodating equivalently as many as 32 remote stations linked over 1200 b/s carrier channels on a realtime basis. This processing power has been achieved by the use of an emulation-type microcomputer, into which a specially developed set of microinstructions are incorporated as part of firmware to get the optimal tradeoff between hardware and software.
    • MFSK Frequency Acquisition and Synchronization for the Jupiter Probe-to-Relay Communication Link

      Fluchel, R. B.; Lee, G. M.; Paddon, E. A.; McDonnell Douglas Astronautics Co. (International Foundation for Telemetering, 1976-09)
      This paper discusses the coarse frequency acquisition problem and the fine frequency tracking problem for a communication link between a spacecraft and a probe entering the atmosphere of Jupiter. A coded noncoherent MFSK modulation format is assumed along with a severely fading link. Fine frequency tracking is shown to be a more serious problem than coarse acquisition.
    • An Adaptive Intrusion Data System

      Johnson, Charles S.; Sandia Laboratories (International Foundation for Telemetering, 1976-09)
      An Adaptive Intrusion Data System (AIDS) was developed to collect data from intrusion alarm sensors as part of an evaluation system to improve sensor performance. AIDS is a unique digital data compression, storage, and formatting system. It also incorporates capability for video selection and recording for assessment of the sensors monitored by the system. The system is software reprogrammable to numerous configurations that may be utilized for the collection of environmental, bi-level, analog and video data. The output of the system is digital tapes formatted for direct data reduction on a CDC 6400 computer, and video tapes containing timed tagged information that can be correlated with the digital data.
    • Pulse Code Modulation Recording for Telemetry Applications

      Waggener, William N.; EMR-Telemetry (International Foundation for Telemetering, 1976-09)
      The problems of signal design and detection and multitrack synchronization are examined for pulse code modulation high-density digital recording. Theoretical bit error probability results are compared with experimental data taken for bandlimited conditions typical of tape recorders. The problem of synchronizing multiple-track data is considered and the maximum likelihood synchronizer is obtained. Variations on the maximum likelihood synchronizer are considered.
    • Reduction of Base Television Bandwidth by Special Sampling Techniques

      Miller, Don C.; Naval Avionics (International Foundation for Telemetering, 1976-09)
      There are many possible ways to reduce the bandwidth of a wideband television system. One of these methods is called Spiraldot which samples the pixels in such a way to keep the data rate resolution high in the center of the TV display but permits reduced resolution and data rate at the extreme edges of the TV image. Bandwidth reductions of 8/1 are possible. A random access memory is required at each end of the data link.
    • Predicting Performance of Convolutional Coded Communication Systems

      Huth, G. K.; Axiomatix (International Foundation for Telemetering, 1976-09)
      The probability of error for a convolutional coded communication system can be predicted using three approaches. The first approach is using Gallager's [1] exponential bound for random codes. The second technique is the use of transfer function union bounds developed by Viterbi [2]. Finally, an approximation to the transfer function developed by Huth and Weber [3] can be used. This paper compares the three approaches for predicting performance and presents results for Viterbi decoding bit error probability, burst error probability, and decoder memory length.
    • Timesharing without Synchronization

      McEliece, Robert J.; Rubin, Arthur L.; Caltech’s Jet Propulsion Laboratory (International Foundation for Telemetering, 1976-09)
      The capacity region of a multiple-access channel has recently been identified as the convex hull K̄ of a certain set K of points in the first quadrant of the (R₁,R₂) plane. For a pair of rates in K, a more or less standard random coding argument can be used to show the existence of a good pair of codes. But for points in K̄-K, it is apparently necessary for the two senders to use some form of timesharing to achieve the desired rates. However, in order to timeshare, at least one of the senders must have knowledge of the other's phase; and in many practical situations this knowledge does not exist. In this paper we investigate the problems which arise in coding for multiple access channels when the senders cannot synchronize with each other.
    • Simulation of the Effects of Hard Limiting on Image Quality of Synthetic Aperature Radar

      Lipes, Richard G.; Butman, Stanley A.; Caltech’s Jet Propulsion Laboratory (International Foundation for Telemetering, 1976-09)
      Starting with a magnetic tape of a scene viewed by the ERTS (Landsat) satellite, we simulated the radar return of reflectors whose average intensity matched that of the picture elements in the scene. The returns were processed in three ways: normally or with no quantization, with a procedure simulating IF (intermediate frequency) hard limiting, and with a procedure simulating video (baseband) hard limiting. For each type of processing we developed an image for a one, two, and four-look system. We found that IF limiting is slightly better than video limiting, while both can be reasonable trade-offs of image quality for reduced data rates when the number of looks is four or less. These conclusions are supported by photographs representing the different processing techniques.
    • A Digital Instrumentation System for Automotive Impact Tests

      Hu, A. S.; Bean, S. P.; Maure, J. J.; New Mexico State University (International Foundation for Telemetering, 1976-09)
      Automotive impact tests require the transmission of large amount of measurement data through drag cables. The traditional practice of using FM technique is tedious and expensive. An on-board PCM system which accepts 112 analog inputs and 91 bi-level inputs has been used successfully at the Daisy Impact Sled Test Track located at the Holloman AFB. This system utilizes a two-conductor pair drag cable. It can also be telemetered by pulse modulating a radio frequency carrier.
    • Distributed Control ... Relevance & Ramification for Utility and Process Applications

      Keyes, M. A.; Bailey Meter Company (International Foundation for Telemetering, 1976-09)
      Distributed digital control systems have appeared structurally desirable for many years. The concepts of hierarchial control and distributed risk were advanced as necessary structural considerations in the control of large scale systems almost coincidentally with the advent of modern electronic instrumentation and digital process control computers. The logarithmic growth patterns of semiconductor technology over the last two decades and the availability of microprocessors and other manifestations of large scale integrated circuitry have finally converted the distributed digital control system from a structurally desirable nicety to an economic inevitability. This paper examines the relevance of distributed digital control systems in the rigorous industrial environment of energy, utility, and process control applications. Design considerations leading to minimization of total installed system costs while retaining the necessary system flexibility to allow user reconfiguration to meet changing process or product needs are delineated. The twin problems of reliability and maintainability are examined in the context of allowable structural degradation concepts which must be inherent in the design of any distributed system.
    • Frequency Response of Tape Transport Servo Systems

      Law, E. L.; Pacific Missile Test Center (International Foundation for Telemetering, 1976-09)
      A method of measuring the frequency response of the tape servo system of analog magnetic tape recorder/reproducers is presented. The servo responses of three tape machines were measured using this method. The results of these measurements are shown to be in good agreement with the difference (in decibels, (dB)) between the flutter spectra in tachometer and tape servo modes. It is also shown that all three servo systems amplified some flutter components. Therefore if the flutter spectrum of the record machine is known, the total flutter can be reduced by carefully choosing the reproduce machine.
    • MIDISS: A Unique Multi-Processor Telemetry Ground Station

      Feinberg, Donald L.; Spacetac, Inc. (International Foundation for Telemetering, 1976-09)
      An optimum architecture for real-time telemetry data acquisition and display has been developed. It provides a high degree of flexibility and throughput while using a minimum of hardware: as applied to the MIDISS system, this approach enables users to specify data processing for each sensor on several satellites independently of downlink formats. Each user can specify and modify CRT displays without interrupting the data processing performance. Processing may include algebraic manipulation, logical branching, logic products, time averaging, etc. This flexibility is provided by SPACETALK, a FORTRAN-like language that enables the user to deal with each sensor by name. Users can also format and transmit uplink commands. Hardware minimization is evidenced by MIDISS's compactness. It consists of a 16-bit minicomputer and a SPACEPIPE (microcomputer-based, front-end processor) that decommutates multiple downlinks, provides rate-buffering, and performs data compression and alarm-checking. The minicomputer is thus free to perform extensive data processing for those downlink channels that are changing at significant rates,
    • Maximum Likelihood Decoding Scheme for Convolutional Codes

      Ng, Wai-Hung; Kim, Frank M. H.; Tashiro, Satoru; The Boeing Aerospace Company (International Foundation for Telemetering, 1976-09)
      In recent years the application of coding techniques to enhance digital data transmission has become widely accepted. In general, one would assume that a maximum likelihood decoding of convolutional codes would be impractical for long constraint length codes because the general approach of sequential decoding algorithms utilize very few properties of the code and hence require a considerable effort to decode the received data sequence. In this paper, several structure and distance properties of the convolutional codes for different constraint lengths are derived and utilized in developing an efficient maximum likelihood decoding scheme. Under the proposed decoding threshold conditions, which are functions of the distance properties of the utilized codes, the required number of decoding operations can be reduced markedly. The analysis has been supported by computer simulations and by the development and testing of a prototype decoder. Key results are presented and discussed.
    • The Joint AEROSAT Evaluation Programme

      Geigner, Oskar L.; AEROSAT Coordination Office (International Foundation for Telemetering, 1976-09)
      The Joint AEROSAT Evaluation Programme has been established by several European States, the United States and Canada in response to recommendations of the 7th Air Navigation Conference of the International Civil Aviation Organisation (IACO) held in April 1972 in Montreal. This group of 11 States has agreed to conduct a single international progranne of experimentation and evaluation in order to facilitate the application of satellite technology to international civil aviation needs. The institutional arrangement devised for such a joint international programme is defined in a Memorandum of Understanding, which was executed in 1974 between the Federal Aviation Administration (FAA), the European Space Agency (ESA), representing the European States, and Canada, with provisions for participation by other countries in the future. An AEROSAT Council was established to oversee this international cooperative effort. The authority and responsibility for the day-to-day implementation of the Coordinated Programme rests with the AEROSAT Coordination Office (ACO), which was established in June 1975.
    • A Microprocessor-Based Computer Developmental System for Satellite Application

      Redman, Paul C.; COMSAT Laboratories (International Foundation for Telemetering, 1976-09)
      This paper describes the hardware and software requirements for a microprocessor-based onboard computer developmental system. In particular, it describes the use of standardized modules which may be assembled in flight form to permit the microprocessor to become a viable alternative to dedicated hard-wired logic implementation in satellite electronic control applications. In addition, it addresses the problem of using electronic control hardware which is common to a majority of applications, with the uniqueness contained in the software. The processor development system includes the basic characteristics of the onboard processor as well as those of the ground-based software development system. The use of these two components to realize a finished onboard processor system is described, and the efficiency advantages of the developmental system are indicated.
    • Performance Bounds on Spread Spectrum Multiple Access Communication Systems

      Yao, Kung; University of California (International Foundation for Telemetering, 1976-09)
      Several approaches for the evaluation of upper and lower bounds on error probability of spread spectrum multiple access communication systems are presented. These bounds are obtained by utilizing an isomorphism theorem in the theory of moment spaces. From this theorem, we generate closed, compact, and convex bodies, where one of the coordinates represents error probability, while the other coordinate represents a generalized moment of the multiple access interference random variable. Derivations for the second moment, fourth moment, single exponential moment, and multiple exponential moment are given in terms of the partial cross correlations of the codes used in the system.
    • On Zero Memory Nonlinear Transformations of Gaussian Processes

      Wise, Gary; Thomas, John B.; University of Texas; Princeton University (International Foundation for Telemetering, 1976-09)
      This paper treats the second moment properties of a zero memory nonlinearity, given that the input is a stationary Gaussian process. The output autocorrelation function is shown to be expressed conveniently in terms of the input autocorrelation function and a set of coefficients describing the ZNL. Two theorems are proved concerning the output process bandwidth. The first shows that the output bandwidth is generally greater than the input bandwidth. The second gives necessary and sufficient conditions for the output process to be strictly bandlimited.
    • Distribution of Intelligence and Input/Output in Data Acquisition Systems

      Rose, Charles W.; Schoeffler, James D.; Case Western Reserve University; Cleveland State University (International Foundation for Telemetering, 1976-09)
      Low cost, high performance microprocessors are being used in several distributed intelligence architecture to replace conventional data acquisition systems. Each distributed topology has certain attributes which affect its suitably for data acquisition applications: cost and position modularity, behavior in the presence of a fault, logical complexity, and bottlenecking. The software organization of these systems is impacted by the distribution of intelligence and input/output, particularly in the areas of task communication, error recovery, data base management, and operating systems structure. A ring structure has been developed for data acquisition and control, which uses distributed microprocessor intelligence and modified serial CAMAC protocol. A general purpose instrument and communications control module based upon INTEL 3000 microprocessors has been built.
    • A Low Level Amplifier for Precision Multiplexing

      Temkin, Bruce M.; General Dynamics (International Foundation for Telemetering, 1976-09)
      An amplifier has been designed for high or low level multiplexing for aerospace PCM data acquisition systems. It was designed to provide "instrumentation amplifier" quality under conditions of high common mode, high or low rate random access operation and broad operating temperatures. It has shown versatility in operation, provides common mode rejection in excess of 125 db (RTI) and can be tailored for a drift temperature coefficient of less than 0.2 μV/°C (RTI)
    • An Operational Video Tape Recording System Utilizing Irig Standard 129-73 [1] Segmented Helical Scan Recording Format

      Damron, S. S.; Schoettmer, G. L.; Strahm, A. E.; Echo Science Corp. (International Foundation for Telemetering, 1976-09)
      Part I. An Operational Video Tape Recording System. An Operational Video Tape Recording (OVTR) system has been developed which fulfills the requirements of the USAF prime specification ASD/ENACC-73-4. The system is comprised, in part, by a highly versatile MIL-E-5400 Airborne Video Recorder and Remote Control Unit which are designed to produce high band [2], [3] video recordings in the environments encountered on deployment in jet fighter aircraft. The companion ground system consists of a video recorder/reproducer for playback of mission tapes and a video Discassette® recorder/reproducer with slow motion/stop action capability for complete analysis of the recorded data. The system design incorporates multi-line rate flexibility to provide record capability of video signals from a multitude of electro-optical sensors including FLIR, LLTV and scan converted radar. The high band performance of the OVTR system makes it suitable for utilization with numerous weapon systems such as PAVE TACK, TISEO, MAVERICK, WALLEYE, HOBO and PAVE SPIKE and various airborne ASW applications. Part II. Expanded Capability for a Wide Range of Instrumentation Applications. The OVTR system is easily expanded in capability to enable the recording of any type of instrumentation data that fits within a 6.5 MHz bandwidth, such as an 8 mB/s serial digital stream, radar, spread spectrum or other down converted communications data. The system features continuous data reproduction capability with no switching transients resulting from sequentially recombining the segmented scan data. The very precise timebase stability and high linearity are key performance factors in enabling the handling of these signals with extremely high fidelity. Further extensions in bandwidth, SNR and time-base stability are under development. Predictions are made on expected performance improvements. Other developments to extend the versatility of the transport systems will be discussed.