• 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.
    • Method for Determination of System Parameters in Telemetry Baseband Modulation Systems

      Rosen, Charles; Microcom Corporation (International Foundation for Telemetering, 1976-09)
      The purpose of this article is to complete the work for specifying the system parameters for all types of modulation used in telemetry systems. The original work is contained in the ITC Proceeding Volume 10 1974, and deals only with FM/FM systems. The combined works of the two articles will consider single type modulation formats, or a combination of the different types of modulations used in present day system.
    • Digital Data Transmission in a PAM Communication System

      King, D. A.; Pacific Missile Test Center (International Foundation for Telemetering, 1976-09)
      This paper presents the results of an experimental evaluation of the effectiveness of digital data transmission in a pulse-amplitude modulation (PAM) communication system. A PAM communication system was simulated and equipment was developed to obtain experimental results indicative of PAM's effectiveness in transmission of digital data. The results consist of word, channel, and bit error probability curves for different numbers of digital bits per PAM channel. The digital bits were converted to analog voltage levels which amplitude-modulated selected PAM channels. After decommutation the digital bits were recovered from the analog voltage levels by an analog to digital conversion. The data indicates that the number of bits per channel should be 4 or less depending upon the digital data quality requirements. The error probability curves can be used to determine whether or not a PAM communication system can telemeter digital data within given constraints. In addition, the results provide guidelines for the implementation of digital data in a PAM system.
    • 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,
    • Optimal Link Capacity Assignments in Teleprocessing and Centralized Computer Networks

      Rubin, Izhak; UCLA (International Foundation for Telemetering, 1976-09)
      We consider a centralized network model representing a teleprocessing or a centralized computer communication network. The network is topologically described by a tree structure. A single central node represents a data-processing center, while the other nodes correspond to remote terminals. A maximal average message delay value is prescribed. A cost function is assumed to incorporate a term representing link costs, dependent only on the link flows, and a term involving weighted (distance related) sum of the powers of the link-capacity values. We then solve for the optimal link capacity assignment, yielding the minimal value of the cost function under the prescribed maximal message delay value.
    • Broadcast Channels: Some Recent Developments and Open Problems

      Leighton, William J.; Tan, Harry H.; Princeton University (International Foundation for Telemetering, 1976-09)
      In this paper we consider some recent developments and open problems on broadcast channels. In particular we consider general discrete memoryless broadcast channel with two information sources. For the case where the two sources are independent we define a rate region R and show that arbitrarily reliable transmission of information over a general broadcast channel may be achieved with suitable coding at all rates in R. For the special case of degraded broadcast channels, R reduces to a previously known expression for the capacity region. R is calculated for a nondegradable broadcast channel which shows that previously known achievable rate regions can be substantially improved upon. We also define an achievable rate region for the case of dependent information sources. Finally, some open problems are discussed.
    • 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.
    • 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.
    • 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.
    • 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.
    • Universal Source Coding of Finite Alphabet Sources

      Omura, Jim K.; University of California (International Foundation for Telemetering, 1976-09)
      The application of Shannon's rate distortion theory to real data compression practice has been limited by a lack of effective distortion measures for most real users and incomplete statistical knowledge of real sources. Universal source coding techniques attempt to overcome the latter limitation by developing codes that are effective (in the sense of approaching the theoretical rate distortion limit) for a large class of sources. Here we examine one such technique for sources with finite alphabets where source sequences are divided into composition classes and a universal code is formed from codes designed for each composition class.
    • Calibration of Analog Measurement and Telemetry Systems

      Grant, Eugene; Martin Marietta Aerospace (International Foundation for Telemetering, 1976-09)
      A basic requirement of modern telemetry and instrumentation is a reference or standard to measure against. A brief survey of early flight tests and missile measurement systems shows the development of analog calibration. Frequency Modulation (fm), telemetry, Pulse Amplitude Modulation (PAM), and commutator calibration will be discussed, as well as measurement resistance calibration comparison and the newer actual instrument stimulation techniques. Factors influencing calibration stability and accuracy will be reviewed with a qualitative discussion of accuracy and frequency of calibration as a function of system requirements and measurement accuracy. Digital techniques and components now allow greater accuracy, stability and minaturization of calibration systems. Low power Schottkey transistors, transistor logic (TTL) and Complementary Metal-Oxide Semiconductor (CMOS) circuitry allows ease of design of calibration systems. With these newer calibrators, no measurement system should suffer from a lack of accurate calibration.
    • An FSK/FDM Multiplexed Fiber Optics System for Multichannel Asynchronous Digital Data Transmission

      McDevitt, F. R.; Patisaul, C. R.; Harris Corporation (International Foundation for Telemetering, 1976-09)
      In this paper the use of frequency division multiplexing to reduce the cost of fiber-optic digital data interconnects is investigated. An analysis is performed to determine the level of multiplexing achievable for a typical optical cable link and the cost of the multiplexed link is compared to that of all-parallel transmission for link distances of 0.5, 1.0 and 2.0 km and data rates of 100 kb/s and 1 Mb/s. The results of this work show that for the present and the near-term future, at least, multiplexing offers substantial cost savings over all-parallel transmission.
    • Cost-Effective Coding Implementations for Computer Communication Systems

      Chien, R. T.; Coordinated Science Laboratory (International Foundation for Telemetering, 1976-09)
      Due to the recent developments in computer hardware and cost reduction, many powerful coding techniques can now be implemented to achieve high reliability at low cost. In this paper we examine the necessary ingredients for successful applications and delineate the systems variables and their inter-relationships. A number of sample applications will be presented to illustrate a systematic procedure to evaluate, select design and implement high performance and low cost systems for error correction and error detection. Implementation approach is considered including hardware, software, microprogramming ROMs, RAMs and LSI.
    • Dual-K Convolutional Codes for Noncoherently Demodulated Channels

      Odenwalder, U. P.; LINDABIT Corporation (International Foundation for Telemetering, 1976-09)
      While the advantages of convolutional coding for coherently demodulated channels have become widely accepted, less work has been done on coding techniques for noncoherently demodulated channels used in channels experiencing fading or intentional interference. Here we describe a simple class of convolutional codes called dual-k [1] codes for use on 2ᵏ-ary orthogonal signal modulated channels and show how they can be used with soft-decision Viterbi decoding on noncoherently demodulated channels. The main result of this paper is a derivation of a closed form expression for the transfer function [2], T(D,N,L), for optimum (in the sense of best Hamming distance) dual-k convolutional codes. Examples of the technique of obtaining upper bounds on the bit error probability using this transfer function are also given for a noncoherently demodulated Rayleigh fading channel.
    • Comparison of PCM Codes for Direct Recording

      King, D. A.; Pacific Missile Test Center (International Foundation for Telemetering, 1976-09)
      The bit packing performance of randomized-non-return-to-zero (randomized- NRZ,) odd parity-NRZ, delay modulation, and bi-phase (Bi-Ø) in direct recording was experimentally compared at a bit error probability (BEP) of 10⁻⁶. The effect of bit patterns, record and reproduce levels, bias level, tape speed, tape recorder bandwidth, bit synchronizers, and crossplay between tape recorders on bit packing density was investigated. At high bit packing densities, significant variations in data quality were found for changes in these parameters. This imposes limitations on practical bit packing densities. Some bit synchronizers were found to seriously reduce bit packing densities. Results show randomized-NR.Z to be superior to the other codes in bit packing density.
    • A Wideband-PCM Recorder for the Space Shuttle Orbiter

      Petit, R. D.; Odetics, Inc. (International Foundation for Telemetering, 1976-09)
      A wideband-PCM recorder has been developed for use in the avionics instrumentation subsystem of the Space Shuttle Orbiter. In direct contrast with the single function Apollo and Skylab recorders, this recorder is designed to meet a variety of present and future applications. The Shuttle recorder uses the tape transport and motor drive design from the NASA-Goddard Space Flight Center (NASA-GSFC) Standard Tape Recorder. This design was directed by the NASA-GSFC with funding provided by the Low Cost Systems Office at NASA Headquarters. Recording is accomplished on up to 14 data tracks with analog or digital data inputs. FM multiplexed analog frequencies of up to 2 MHz and digital rates of 1 Mb/s are accommodated at a tape speed of 120 inches/second. Recording time in the analog mode varies between 4 minutes for 2 MHz data to 80 minutes for 100 KHz data. The total digital data storage is 3.44 x 10⁹ bits with recording times from 1 hour for 1 Mb/s data to 19 hours for 50 Kb/s data in the serial track switching mode. A versatile command decoder and control interface are used for eight primary modes of operation. The recorder responds to over 7,000 commands which are combinations of the eight modes, four tape speeds, four delay times, four run periods and track selection. The commands are formatted as 16 bit words by onboard computers or simple, single switch panel commands initiated by the astronauts. The Shuttle recorder uses a hermetically sealed transport unit, occupies approximately 2,000 cubic inches and weighs 41 pounds. Operation through launch and re-entry vibration environments is accomplished by use of isolators which mount the transport unit to the electronics unit. Tape life is in excess of 20,000 passes without maintenance.
    • Candidate Receivers for Unbalanced QPSK

      Weber, Charles L.; University of Southern California (International Foundation for Telemetering, 1976-09)
      Candidate receivers for unbalanced QPSK signal foremats have been studied. The fourth power receiver is shown to be an unsatisfactory choice unless the power division is close to 50-50 or 100-0. The Costas loop receiver which tracks on the high data rate signal of the unbalanced QPSK waveform is shown to perform satisfactorily. Approximate error rate computations, show that the Costas loop considered performs within a few tenths of a dB of the ideal receiver.
    • 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.
    • Magnetic Tape Synchronizer/Controller

      Schoeck, K. O.; Martin, S. W.; Vandenberg Air Force Base; Datatape (International Foundation for Telemetering, 1976-09)
      A method has been developed to time synchronize multiple wideband magnetic tape recorder/reproducers to allow realtime data merging of tapes from various tracking stations. The system operates using either IRIG A and/or IRIG B time codes, and maintains synchronization within 10 microseconds using IRIG A and 50 microseconds using IRIG B.