• The Apollo Launch Data System

      Quinn, M. J.; Nasa Manned Spacecraft Center (International Foundation for Telemetering, 1966-10)
      The development of the Apollo Launch Data Telemetry System, the real-time interface between the Merritt Island Launch Area (MILA) and the Mission Control Center-Houston (MCC-H), is reviewed from its beginning through the system planning stages, and then into the final hardware implementation.
    • Application of Walsh Functions to Data Acquisition Systems

      Morton, Walter (International Foundation for Telemetering, 1966-10)
      The Walsh functions are considered with respect to the following system functions: 1. Concise signal representation. 2. Arithmetic operations. 3. Convolution and filtering. 4. Transfer function analysis. 5. Special measurements and functions: 5.1 Phase. 5.2 Digitally controlled function generator (DCFG). 5.3 Power density spectrum. 5.4 Correlation functions. The foregoing operations are required of equipment in the following areas of application: 1. Seismic data processing. 2. Hybrid data systems and simulation studies. 3. Special purpose Instrumentation.
    • Channel Noise - A Limiting Factor on the Performance of a Class of Adaptive Techniques

      Raga, Gerald L.; Electro-Mechanical Research Inc. (International Foundation for Telemetering, 1966-10)
      The effects of channel noise on a class of adaptive sampling techniques based on the concept of removal of redundant data samples were investigated. Assuming a system of fixed bandwidth and fixed transmitter power, the channel noise forces the adaptive system to operate at a lower bit error probability than the equivalent PGM system since in the adaptive system each transmitted bit represents more information. This limitation was partially overcome by adding error criterion of unequal weighting to the data which enabled the system to operate at essentially the same bit error probability as the PCM system with a net coding efficiency greater than the coding efficiency of the error-correction code. Experimental results from subjective tests, and the RMS error demonstrate that a new error criterion must be developed for the class of adaptive techniques.
    • A Compatible Double Sideband/Single Sideband/Constant Bandwidth FM Telemetry System for Wideband Data

      Frost, W. O.; Emens, F. H.; Williams, R.; Marshall Space Flight Center (International Foundation for Telemetering, 1966-10)
      This paper reviews the telemetry problems involved in transmission of wideband phenomena such as shock, vibration, and acoustic measurements. Three approaches to this problem have recently received considerable attention from the telemetry community: SS/FM, DSB/FM, and constant bandwidth FM/FM. The relative capabilities and limitations of these three techniques are discussed and their S/N performance and r-f bandwidth utilization efficiency are compared. An arrangement whereby the three techniques may be flexibly intermixed on a single RF carrier is then described. Examination and consideration of the merits of this arrangement as a future standard telemetry technique is proposed.
    • Computer Controlled Telemetry Station

      Strock, O. J.; Defense Electronics, Inc. (International Foundation for Telemetering, 1966-10)
      A telemetry ground station under complete operational control of a general-purpose digital computer is described. The six subsystems which comprise the station are examined in some detail to show the method of control and the flexibility and speed of operation. A specific application is described and other potential applications are explored.
    • Desired Telemetry System Characteristics for Shock, Vibration, and Acoustic Measurements

      Himielblau, Harry; Subcommittee G-5.9 on Telemetry Requirements; SAE Committee G-5 on Aerospace Shock & Vibration (International Foundation for Telemetering, 1966-10)
      For over a decade structural dynamicists and acousticians have registered general dissatisfaction concerning the limitations of telemetry systems, especially the insufficient number of channels and insufficient data bandwidths. To spell out the users' need for present and future telemetry, a representative group of dynamicists was organized under the SAE. Requirements for number of channels per flight, data bandwidths, minimum dynamic range (with stationary and transient data signals considered separately), certain accuracy, phase and other characteristics were established. The subcommittee is hopeful that this information will spur the telemetry community into developing and standardizing on new systems with superior characteristics.
    • Error Detection and error Correction Under the Conditions of Quarternary Decision Logic Techniques

      Brothman, A.; Yanis, C.; Halpern, S. J.; Miller, A. H.; Sangamo Electric Company (International Foundation for Telemetering, 1966-10)
      The hardware and theory of a multi-threshold bit decision technique called Quarternary Decision Logic are described. Quartenary Bit Decision Logic results in two simultaneous decisions on each received bit of a binary digital transmission: (1) a binary status decision; and, (2) a reliability decision which reflects on the presence/absence of multilation in the bit. Both decisions are based on a Shannon Integration of the received information over the whole bit interval. The ability to assess bit mutilation is then used to develop adjustable security-enforcing restraints on error correction and the receiving process itself. These restraints are developed by a Word Security Logic which keeps a "mutilation count" on each received word, The "mutilation count" per word results in a "Correction Permit/Inhibit" and a "Receiving Permit/Inhibit" output on each word. The "Correction Permit/ Inhibit" output bars error correction when the risk of a spurious correction is high. The "Receiving Permit/Inhibit” output blocks receiving when the risk of a direct evasion of security is high. The improvement in bit decision security and the improvements in security against spurious correction and direct evasions of Error detection are evaluated quantitatively in comparison to conventional single-threshold techniques, These improvements enable secure operation with lower redundancy coding systems because of the information gain which Quarternary Decision Logic provides. The possible contributions of Quarternary Decision Logic to self-adaptive data transmission systems and to automatic line equalization are explored in the section entitled "Conclusions".
    • Evaluation of Redundancy Reduction Algorithms

      Simpson, R. S.; University of Alabama (International Foundation for Telemetering, 1966-10)
    • An Experimental Investigation of the Capture Performance of FM Receivers

      Castellano, A. J., Jr.; Data-Control Systems, Inc. (International Foundation for Telemetering, 1966-10)
      This paper reports on the investigation of the effect of telemetry receivers capture ratio on overall system accuracy. Receivers with normal and improved capture ratio were compared to evaluate the methods used to measure capture ratio, determine the effect of I-F filter characteristics on capture ratio, and establish the penalty of bandwidth and distortion results including waveforms, photographs and spectral diagrams for various values of co-channel interference.
    • Factors Limiting UHF Telemetry Systems Operation

      Gong, H.; Herman, R. T.; Konop, P. L.; The Mitre Corporation (International Foundation for Telemetering, 1966-10)
      Demands on the use of that portion of the radio spectrum from 225 MHz to 400 MHz for military tactical operations have made it necessary to vacate the VHF telemetry band from 215 MHz to 260 MHz by I January 1970 and to convert such operations to UHF telemetry bands from 1435 MHz to 1540 MHz and 2200 MHz to 2300 MHz. The environmental, physical, and practical limitations imposed on telemetry system performance when operation is moved from VHF to UHF are described in this paper. The topics which are discussed include path loss, multipath, flame plasma effects, expected Doppler shift and Doppler rates, natural noise limitation, UHF transmitter power and stability, receiving system noise figures, airborne antennas and ground antennas. UHF telemetry operation in support of missions for aircraft, ballistic, orbital, and deep-space vehicles is evaluated mainly through a comparison with similar operations at VHF. The results of this study show that there are no technological factors which limit the instrumentation of an adequate UHF conversion.
    • International Telemetering Conference Proceedings, Volume 02 (1966)

      International Foundation for Telemetering, 1966-10
    • Low Level F. E.T. PAM Multicoder

      Gregory, Terence R.; General Devices, Inc. (International Foundation for Telemetering, 1966-10)
      This paper describes a new all solid state airborne low level PAM multicoder that employs N-channel FET for all the analog switching functions of the system. The unit features a 72KHz true chopper amplifier that affords complete isolation between input and output. This unit is fully developed and went into production in June 1966 offering many advanced features to airborne telemetry system users. Each input channel presents a true differential analog switch into the low level D. C. amplifier. The operating characteristics such as C. M. R. (100 db) out to 1KHz, no D. C. drift or gain-change, and selectable pedestal levels add to ease of operation and flexibility. Heavy use of integrated circuits was also made including monolythics, hybrids and discrete elements. The gating logic, chopper amplifier front end, and carrier amplifier/synchronous demodulator each have a separate power supply winding thus providing excellent isolation for user applications. Mechanical construction employs plug in boards affording ease of manufacture and complete interchangeability of boards between units. The system is discussed as to unique features and techniques necessary to build the unit and satisfy stringent specifications.
    • Magnetic Memory Techniques for High Accelerations

      McAlexander, J. C.; Cook, S. C.; Bell Telephone Laboratories; Sandia Corporation (International Foundation for Telemetering, 1966-10)
      A system to obtain and record impact data at accelerations of 3000 g’s has been designed around a 1024 word, 12 bits per word, piggyback twistor memory. Memory construction and potting techniques were developed to minimize the effect of large acceleration forces. The memory and system tests prove that the memory can withstand shock signatures beyond its original design requirements.
    • Magnetic Recording of Radar Data

      Young, Ronald E.; Ampex Corporation (International Foundation for Telemetering, 1966-10)
      The methods presently utilized for magnetic recording of radar data are explained with reference to basic radar types. The PPI radar has a time continuous video signal and generally requires a transient free recorder of moderate data bandwidth. In addition, means must be provided to record the azimuth information in either synchro, sine-cosine or digital form. Such means are available and recommended approaches for each type of data are given. Time discontinuous radar such as the missile tracking monopulse group may utilize recorders normally designed for video service if certain pulse spacing criteria are observed. The wider data bandwidth of this type of signal makes the use of rotary head recorders mandatory. There are many applications for radar recording. Some of those described include operator training, debriefing and scoring and operational evaluation of the radar facility. The radar recorder can be a significant aid in data analysis for signature determination of satellites and planetary mapping. The radar recorder also furnishes a close facsimile of the operating radar signal for system evaluation when there are no targets to observe or when the main radar is shut down for any reason. As an illustration of the application of magnetic recording to the radar system an airborne data acquisition recorder is described along with a companion ground reproducer. These two units are presently in use in the evaluation of an airborne radar system and offer significant advantages over previously available recording equipment. The development of time base stable magnetic tape recorders capable of handling data bandwidth in excess of 5 MHz has added another facet to the instrumentation field - that of recording radar data on a real time basis for analysis at a later time. The discussion that follows illustrates the methods used in magnetic recording of radar data and cites a typical recording system.
    • Magnetic Tape Recorder Spectral Purity

      Bradford, R. S.; 3M Company (International Foundation for Telemetering, 1966-10)
      The data recovery and reduction processes of various telemetering systems have clearly demonstrated the critical role of flutter and time errors in instrumentation recording and reproduction. One of the effects of these errors is that of "frequency smearing" of individual recorded/reproduced sine wave components. The advent of precision tape speed servo control has reduced these errors to a point where a detailed examination of the residual effect becomes both possible and profitable. The detailed measurements of the resultant spectrum of a recorded/reproduced sine wave component are described. These are quantitatively analyzed and interpreted in terms of the flutter and time error characteristics of the recording/reproduction system.
    • Microsecond Resolution Telemetry

      Moore, Jerry D.; Sandia Corporation (International Foundation for Telemetering, 1966-10)
    • A Miniaturized RF Acceleration Measuring System

      Trapp, D. L.; Sandia Corporation (International Foundation for Telemetering, 1966-10)
      This paper will describe the design and development of a miniaturized high-shock package utilizing an FM modulated 19.8 mc transmitter and a piezoresistive accelerometer. This program was initiated in October 1965 for the purpose of measuring deceleration profiles generated by small diameter (1-1/4 inch) vehicles that penetrate targets of known composition with input velocities up to 1500 feet per second. Shock levels were anticipated to be in the 0 - 10,000 g range, with rise times varying as a function of projectile ogives and anticipated to be as fast as 100 μsec. The system was designed to an existing volume described by a right circular cylinder, 1 inch in diameter by 6 inches in length, and an allowable volume of 3/4-inch diameter by 4-inches long was allocated for the 19.8 mc transmitting antenna. The first operational usage of this system was in late January 1966.
    • A New Analog Magnetic Recording Technique

      Johnson, W. R.; Jorgensen, F.; Fairchild Winston Research (International Foundation for Telemetering, 1966-10)
      The magnetic recording process using ac bias is reviewed and applied in a discussion of recording heads. The difficulties in obtaining a sharp gradient are explained. A new magnetic recording head that overcomes the weaknesses of conventional heads is described and compared with the conventional ring core head. Performance data are listed and show improvement in frequency response, decrease in harmonic and intermodulation distortion, reduced electronics and higher reliability.
    • New Concept in High Reliability Tape Recorders for Spaceborne Data Storage

      Burdorf, D. L.; Kinelogic Corporation (International Foundation for Telemetering, 1966-10)
      The need for large bit capacity in on-board data storage for deep-space probes, spacecraft, satellites, and aircraft, has created a requirement for a tape recorder of ultra-high reliability. In an ideal recorder, the conventional capstan would be eliminated and the reels would be driven such that the linear velocity and the tension of the tape between reels would be constant from the beginning to the end of the reel. The heads would also be the only elements in contact with the tape. Reliability would be enhanced by driving the reels, rather than the tape, through a reduction in the number of moving parts. Reducing the number of elements in contact with the tape would also increase tape life. The Iso-Elastic Drive, closely approaches the ideal recorder drive system. The reels are driven by a seamless polyester belt which is in direct contact with the periphery of the tape reel. The belt is driven at constant linear velocity (resulting in low flutter) and in such a manner that it generates a constant tension in the tape connecting the two reels and passing across the heads. Constant tape tension in a high-reliability recorder is necessary in order to optimize 1) tape tracking and guidance, 2) effective bias level on the tape during direct-type recording, 3) playback level, 4) head wear, and 5) drop-outs. The Iso-Elastic Drive reduces the number of moving parts by approximately 30% as compared with conventional recorders. The tape drive has the additional desirable characteristic of operation equally well in either direction.
    • New Concepts for Telemetry Converters

      Friend, Larry; Motorola, Inc. (International Foundation for Telemetering, 1966-10)
      Future requirements to convert present VHF telemetry receivers to L and S-bands can be satisfied by relatively simple solid state microwave converters. Use of the recently developed Schottky barrier diodes in balanced mixers along with high frequency field effect transistors in the intermediate frequency VHF preamplifiers, show considerable promise of providing low system noise figure (e.g. 5.5 dB) and low intermodulation distortion. These broadband converters have the potential advantages of minimum cost, size, weight, and power consumption, thereby providing a convenient and practical means for converting existing telemetry systems to the new frequency bands. Design considerations and predicted performance characteristics are presented for solid state converters of this type.