ABOUT THE COLLECTION

The International Telemetering Conference/USA (ITC/USA) is dedicated to the promotion and stimulation of technical growth in telemetering and its allied arts and sciences. It is the premier annual forum and technical exhibition providing telemetry specific short courses, technical papers from professionals and students, and exhibits of the industry’s leading companies. ITC/USA is sponsored by the International Foundation for Telemetering (IFT), a non-profit corporation dedicated to serving the technical and professional interests of the telemetering community.

This collection contains the proceedings of the second International Telemetering Conference, October 18-20, 1966. The conference, sponsored by the International Foundation for Telemetering, was held at the Ambassador Hotel in Los Angeles, California.

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Recent Submissions

  • Predetection Diversity Combiner

    Casson, William Holton; Defense Electronics, Inc. (International Foundation for Telemetering, 1966-10)
    Pre-detection diversity combining provides a number of advantages in telemetry data reception, particularly when used in conjunction with pre-detection recording equipment. These advantages include optimal ratio signal combining before pre-detection recording, pre-detection signal-to-noise ratio and threshold improvement, higher improvement in demodulated signal-to-noise ratio as compared with postdetection combining, and a number of operational simplifications, which are further enhanced when the combiner is used with dual channel receivers. Laboratory tests verify predicted performance. Additional quantitative field data is needed, but preliminary results indicate excellent performance, and no problems in maintaining phase lock have been experienced.
  • Polarization-Diversity Telemetry Receivers

    McCann, R. P.; Jones, R. D.; Sandia Corporation (International Foundation for Telemetering, 1966-10)
    Studies at the Langley Research Center of the National Aeronautics and Space Administration have shown that certain physical properties of extraterrestrial surfaces can be determined by analysis of impact-acceleration, time-history signatures obtained by instrumented projectiles (penetrometers). This paper considers the theory and design of a polarization-diversity receiver developed to receive and combine FM/FM penetrometer telemetry data. The signals are radiated by a set of orthogonal magnetic dipoles fed in time quadrature to obtain an omnidirectional radiation pattern similar to the pattern from a conventional turnstile. A special polarization-diversity receiving system is required to reduce the effects of fading of the RF carrier resulting from random changes in the orientation of the radiating antenna system. Various combining techniques are evaluated. Finally, a maximal-ratio, postdetection, dual-channel receiver with dual conversion and subcarrier discrimination developed specifically for the application is described.
  • RF Intermodulation Characteristics of VHF Telemetry Preamplifiers and Receivers

    Jeske, Harold O.; Sandia Corporation (International Foundation for Telemetering, 1966-10)
    Tests have been conducted on ten preamps and six receivers to quantitatively determine their linear operating range. The range of linear operation was determined by the measurement of, or the effects of, intermodulation (IM) products that were produced by the simultaneous application of two input signals. Measurements were made at a frequency equal to twice the frequency of one signal source minus the frequency of the other signal source. Tests of the ten preamps, which included eight solid state units, indicated that their dynamic range varies from approximately 46 to 70 db. Since the IM products of interest vary as the cube of the input signal, the output IM products may vary over a 72 db range, between the preamps tested, for a given input condition. It was found, under the best conditions with some receivers, that their proper operation was prevented by the presence of two signals that were less than 30 db larger than the desired signal. The two interfering signals were located well outside the rated - 60 db bandwidth of the receiver. The results of the tests should provide receiving system designers and operators with a better insight into the problem of RF intermodulation interference. Since no known military interference specifications consider intermodulation as investigated, it is believed that some standard test procedures should be developed by the telemetering community for preamp and receiver testing.
  • Requirement for a Data Quality Assurance Program

    Nichols, M. H. (International Foundation for Telemetering, 1966-10)
    The requirement for a Data Quality Assurance Program for telemetry ground station operations is outlined. Examples are given for frequency division and time division formats to demonstrate that a practical and meaningful program is within the state-of-the-art and in fact that the basic modules have already been developed for commercial communication systems. A program is recommended for expansion of the IRIG Standards to include performance criteria and specifications of end-to-end ground station tests for determining that the criteria are satisfied for each mission.
  • 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.
  • Reconstructing a Serial Pulse Train from Parallel Data Recorded on Magnetic Tape

    Hadady, R. E.; Kinelogic Corporation (International Foundation for Telemetering, 1966-10)
    On-board data stores in deep-space probes, spacecraft, satellites, and aircraft, frequently require the extensive bit storage capability of a magnetic tape recorder. For compatibility with other systems, it is necessary in some cases to be able to reproduce the data in serial form at a synchronous rate. To take maximum advantage of the storage capability of magnetic tape, however, it is desirable in many instances to record the data in a parallel format; i.e., the technique used in magnetic tape recorders used with ground based computers. Reconstructing a serial pulse train with a synchronous bit rate from parallel data recorded on magnetic tape involves some problems which are peculiar to magnetic tape recording equipment. Variations in tape speed (flutter), dynamic skew (wobble) of tape as it passes over the record and playback heads and static skew of the data on the tape resulting from head gap scatter and mean gap azmuth alignment results in nonsynchronous data being generated during playback. To provide synchronous data output, it is therefore necessary to provide a buffer between the output of the magnetic tape recorder and the system accepting the data. Recorder characteristics are examined with respect to their effect on the degree of non-synchronism. Furthermore, the size and complexity of buffers necessary to provide synchronous output data is considered.
  • 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".
  • Refinements on Analysis of PCM Synchronization

    Williard, Merwin W.; Symetrics Engineering (International Foundation for Telemetering, 1966-10)
    In this paper, the author reconsiders some of his previously reported assumptions on an analysis of mean time to establish PCM synchronization, and he provides further insight into the effect of specific synchronization patterns and parameters of the synchronization process. An improvements in one assumption shows how the analysis can provide slightly more accurate results. Specific recommendations are made for standardization of PCM sync patterns.
  • PCM Transmission with Minimum Mean-Square Error

    Clark, G. C.; Totty, R. E.; Radiation Incorporated (International Foundation for Telemetering, 1966-10)
    One source of error in PCM transmission of analog waveform is the bit errors made in the binary sequences representing a particular level. Using a mean-square error criterion, the contribution of this (channel) error to the overall reconstruction error is examined. In particular, general simplified error expressions are derived for arbitrary sequence assignments including error correcting coding. Results are given for the power gain resulting from use of several error correcting codes. The criterion used here is mean-square error (rather than word probability of error) and the coded sequence is constrained to occupy the same time interval as the uncoiled sequence.
  • 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.
  • 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.
  • 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.
  • 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.
  • A Report on the Application of Data Abbreviation on Actual Range Telemetry Data

    Maestre, N. E.; Radio Corporation of America (International Foundation for Telemetering, 1966-10)
    The growing interest in the practical applications of data abbreviation and compaction to efficiently handle large quantities of significant information have led to numerous investigations and studies of this discipline. Although there is great potential in both the airborne and ground applications, it is primarily the latter that led RCA to initial independent data abbreviation and compaction studies. It is the purpose of this report to present results of the practical application of data abbreviation to actual telemetry data recorded on magnetic tapes. The presentation will include the affects of routine parameters, the amount of redundancy information removal, and, the reduction in processing time and recording facilities. Even though these studies involved the use of telemetry data from a mission that has already occurred, the need for the inclusion of data abbreviation devices into the existing ranges to process data in real time is becoming more apparent.
  • 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.
  • Evaluation of Redundancy Reduction Algorithms

    Simpson, R. S.; University of Alabama (International Foundation for Telemetering, 1966-10)
  • Transistor-Magnetic Logic in Aerospace Timing

    Goldman, Samuel C.; Stern, Michael M.; Goldman, David J.; Di/An Controls, Inc. (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.
  • Microsecond Resolution Telemetry

    Moore, Jerry D.; Sandia Corporation (International Foundation for Telemetering, 1966-10)

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