• Intermodulation Effects in FDM Telemetry Systems

      Johnson, C. S.; Sandia Laboratories (International Foundation for Telemetering, 1971-09)
      The performance of a telemetry system is affected by three principal sources: the noise of the electronics, the noise of the transmission link, and the intermodulation noise. Intermodulation noise is a significant contributor to signal-to-noise ratio of a telemetry system and can sometimes be more serious than the other noise sources. The experimental results described in this paper are aimed at showing how serious the intermodulation noise can be to a multichannel telemetry system.
    • A 2-kw S-Band Re-Entry Telemetry System

      Trapp, D. L.; Williams, P. K.; Sandia Laboratories (International Foundation for Telemetering, 1971-09)
      Instrumentation of high-velocity re-entry rocket systems at Sandia Laboratories has been complicated because of dependence on onboard magnetic tape recorders to store data until the carrier emerges from the radiofrequency blackout. This paper describes an approach designed to minimize the effect of the RF blackout by means of employing a sampled data system the output of which consists of 1-μsec pulses of 2-kw RF power level. The effort was initiated in the spring of 1970 for the purpose of obtaining real-time data during the re-entry blackout phase of a Sandia re-entry flight test. Re-entry velocities in the vicinity of 25,000 fps are expected.
    • On the Selection of an Optimum Design Point for Phase-Coherent Receivers Employing Band-Pass Limiters

      Simon, Marvin K.; California Institute of Technology (International Foundation for Telemetering, 1971-09)
      In the design of phase-coherent receivers employing bandpass limiters, it is customary to specify system performance relative to its value at a fixed design point. For a given design point, it is well known that an optimum tradeoff can be found between the power allocated to the carrier and sideband signals. This paper describes an attempt to further improve the performance of such coherent carrier systems by optimizing the design point based upon a given practical optimization criterion. The single-channel system is treated in detail and a brief discussion is given on how to extend the optimization technique to a two-channel system.
    • Electrocardiogram Transmission, the State of the Art

      Firstenberg, A.; Huston, S. W.; Olsen, D. E.; Hahn, P. M.; University of California (International Foundation for Telemetering, 1971-09)
      A comparative analysis of available clinical EKG telemetry systems was conducted. Although present day electrocardiogram diagnosis requires a high degree of measurement accuracy, there exists wide variations in the performance characteristics of the various telemeters marketed today necessitating careful consideration of specifications prior to procurement. The authors have endeavored to provide the physicians with a clear understanding, in terms of the effects on the electrocardiogram, of the factors he must evaluate in order to ensure high fidelity EKG reproduction. A tabulation of comparative parameter values for each unit obtained from manufacturers' specifications and substantiated by standardized performance tests conducted in our laboratory is presented.
    • Coherent Demodulation of Continuous Phase Binary FSK Signals

      Pelchat, M. G.; Davis, R. C.; Luntz, M. B.; Radiation Incorporated (International Foundation for Telemetering, 1971-09)
      This paper gives achievable bounds for the probability of error of continuous phase binary FSK signals on the white gaussian noise channel. Phase continuity, like convolutional encoding, introduces a dependence between adjacent transmitted signals which can be used to advantage in the demodulation process. It is shown that continuous phase binary FSK can provide a given probability of error with 0.8 db less signal-to-noise ratio than antipodal PSK. The paper also shows how the ideas developed for decoding convolutional codes apply to the demodulation of continuous phase FSK with rational deviation ratio.
    • Projectile High-G Telemetry for Long Range Dynamics Measurements

      Mermagen, William H.; Aberdeen Proving Ground (International Foundation for Telemetering, 1971-09)
      Devices to measure the pitching, yawing, and rolling motion of a projectile from on board and telemeter the measurements to ground receiving stations have been developed. Two of these devices, a solar aspect sensor and an accelerometer, are described in detail. The complete telemetry system with g-hardening to survive gun-launch accelerations is described and techniques for high-g are discussed. The results of several recent flight tests of these yawsondes are presented and show the unique usefulness of the instruments for measuring dynamical behavior of projectiles over their entire flight paths. Hitherto such information has not been available to the shell designer or the aerodynamicist.
    • Performance Results for a Hybrid Coding System

      Hoffman, L. B.; NASA (International Foundation for Telemetering, 1971-09)
      Computer simulation studies of the hybrid pull-up bootstrap decoding algorithm hive -been conducted using a constraint length 24, nonsystematic, rate 1/2 convolutional code for the symmetric channel with both binary and 8-level quantized outputs. Computational performance was used to measure the effect of several decoder parameters and determine practical operating constraints. Results reveal that the track length may be reduced to 500 information bits with small degradation in performance. The optimum number of tracks per block was found to be in the range of 7 to 11. An effective technique was devised to efficiently allocate computational effort and identify reliably decoded data sections. Long simulations indicate that a practical bootstrap decoding configuration has a computational performance about 1.0 dB better than sequential decoding and an output bit error rate about 2.5 x10⁻⁶ near the R(comp) point.
    • Preliminary Report on the Development of a Crystal-Controlled L-Band Artillery Telemetry Transmitter

      Richardson, J. F.; Harry Diamond Laboratories (International Foundation for Telemetering, 1971-09)
      Harry Diamond Laboratories (HDL) has a need for gun-rugged UHF telemetry transmitters for use in research and fuze testing programs. An in-house design program was started because of the specialized performance requirements for artillery electronics. This is the first status report on the effort. UHF transmitters are extremely sensitive to physical deformation because small dimensional changes produce reactance changes that can cause an appreciable change in frequency. Since ruggedized crystal-controlled oscillators limit the frequency shift to low levels and therefore permit early acquisition of artillery telemetry signals; a prototype transmitter was constructed to determine the degree of efficiency and compactness that could be obtained at L band. A compact 1510-MHz transmitter having an efficiency of 6 percent at an output power level of 160 mW is described. Physical dimensions are such that the transmitter can be readily potted in any artillery telemetry housing currently in use. Temperature compensation and gun ruggedization tests are currently in progress.
    • A Multispectral Scanner Data Decommutator/Processor for the Earth Resources Technology Satellite

      Waltz, Edward L.; Bendis Aerospace Systems Division (International Foundation for Telemetering, 1971-09)
      This paper describes the design of the telemetry decommutator/processor for multispectral scanner data to be returned by the first two Earth Resources Technology Satellites (ERTS). This unit, referred to as the Multispectral Scanner Tape Decommutator/processor (MSS TDP), is a versatile data handling system which accepts multipletrack tape inputs, providing output formats compatible with a multipletrack tape recorder or a single channel film recorder. The system is organized as a parallel processor, being capable of decommutating and formatting five spectral bands of digital video data. Synchronization and decommutation of skewed multiple-track data is performed with housekeeping and calibration data being transferred to a control computer. A six scan line buffer is asynchronously loaded and synchronously unloaded to remove data skew and reformat the video data. The unit includes a highspeed arithmetic processor which performs radiometric calibration of a single spectral band of video data prior to film recording. The primary function of the MSS TDP will be the processing of receiving site data tapes for conversion to film images.
    • Signal Processing Techniques for a 1000 MB/S Microwave Communication Link

      Ryan, C. R.; Motorola Government Electronics Division (International Foundation for Telemetering, 1971-09)
      Special circuit design techniques must be used for wideband signal processing systems. These techniques are based on the use of a limited number of circuit types with the multiplier/signal switch as the dominant active signal processing element. The capability of this approach is illustrated in the construction of a 1000 MB/S QPSK Modem and a 200 MB/S data regenerator which uses a true reset integrator for optimum bit-by-bit data reconstruction.
    • L-/S-Band Calibration Error Analysis

      Taylor, Ralph E.; NASA (International Foundation for Telemetering, 1971-09)
      A statistical error analysis is performed to determine the degree of uncertainty encountered when calibrating steerable receiving antennas with the solar calibration method. The analysis considers the propagation of precision error indexes. It is shown that a worst-case one-sigma (1σ) uncertainty of ±0.8 dB in system noise temperature occurs for a solar calibration at L-band. Somewhat better precision can be achieved by monitoring the antenna gain-to-noise temperature (G/T) ratio at a station; a worst-case uncertainty of ±0.5 dB (1σ) can be realized. An error analysis is made of a method to determine absolute antenna gain based upon solar flux density. The uncertainty in this type measurement is ±0.7 dB (1σ) at L- and S-band frequencies.
    • An Instrumentation Tape Winder/Cleaner/Certifier

      Read, G. W.; Youngwist, R. J.; Minnesota Mining and Manufacturing Co. (International Foundation for Telemetering, 1971-09)
    • Radiotelemetry for Research on Large Land Mammals

      Buechner, H. K.; Smithsonian Institution (International Foundation for Telemetering, 1971-09)
      The use of radiotelemetry for simultaneously monitoring physiological and environmental parameters, while an animal is being tracked in its natural ecosystem, provides new opportunities for increasing our knowledge about the larger land mammals by the acquisition of new information on their migratory movements, social behavior, bioenergetics, and physiological processes such as thermoregulation and water balance. The perfection of satellite tracking and monitoring systems specifically designed for wild animals, such as caribou and elephants, in remote areas of the Earth is feasible; and such systems hold considerable promise in providing access to information that has been exceptionally difficult to obtain in the past. Challenges in the development of practical radiotelemetry systems include: light-weight, long-lasting sources of power; developing systems that require little power; increasing the variety of implantable physiological sensors; improving the resolution of locations (to 100 m or less) for tracking an animal by satellite; improvement of antennas for greater efficiency in transmissions without interfering with the animal's activities; and interfacing implanted sensor-transmitters with long-range transmitters on the animal's surface. The perfection of systems for attachment of instrument packages to polar bears, elephants, and other wild animals is also demanding.
    • VHF and HF Field Tests with an Interleaved 1/3 Rate Block Code

      Juroshek, J. R.; Institute for Telecommunications Sciences (International Foundation for Telemetering, 1971-09)
      A one-way error correcting system that employs a onethird rate, interleaved, block code was constructed and tested at teleprinter speeds. All system functions including timing and synchronization were tested over a 1300 km VHF ionoscatter path and a 1500 km HF path. The decoder used "minimum-distance decoding." The results showed that coder performance was close to theoretical predictions. A useful secondary output, called the inversion count, was analyzed. A difference in coder performance was noted between the VHF and HF channels.
    • A Technique for Measuring the Behavior of a Navigational Buoy

      Babb, Lowell V.; Wilmarth, Robert W.; Budridge, Gerald J.; Transportation Systems Center; U.S. Coast Guard (International Foundation for Telemetering, 1971-09)
      A prototype instrumentation package has been designed and fabricated to furnish quantitative information about the stability of an ocean navigational buoy. A total of fourteen electro-mechanical transducers were included in the package to yield attitude, acceleration, and mooring chain tension information about the buoy. By utilizing a six channel telemetry data system and a 4-channel command telemetry system, continuous data from selected sets of transducers were recorded and used to determine the types, sensitivities, and ranges of instrumentation best suited to this application. The number of telemetry channels chosen represents the "best guess" number required in the final program which will consist of five separate instrumentation packages. By integrating the two telemetry systems in the prototype unit, a flexibility of operation was realized that yielded large amounts of useful data at a minimal cost.
    • Modulation/Demodulation Techniques for an Optical One-Gigabit/Sec Intersatellite Data Transmission System

      Hance, H. V.; Chow, K. K.; Ohlmann, R. C.; Peterson, D. G.; Ward, R. B.; Lockheed Palo Alto Research Laboratory (International Foundation for Telemetering, 1971-09)
      In selecting a modulation format and modulation/demodulation techniques for a 1-Gbit/sec intersatellite data link, a judicious balance must be struck between a number of more or less contradictory factors for the choice to be an optimum one. Particularly important are the factors that determine the average transmitter input power required, as this has a large influence on launch weight and hence on cost. In this connection, both the inherent efficiency of the modulation format and the power losses involved in the implementation chosen obviously must be taken into account. The latter choice depends, in turn, upon the status of component development assumed, or, alternatively, on the amount of development risk that can be tolerated. Finally, in some applications, the ability of the system chosen to handle a variety of data signal formats and, in particular, to handle asynchronous data streams without requiring complex onboard signal processing such as bit stuffing and bit stream reclocking must be considered.
    • Birds, Large and Small

      Sladen, W. J. L.; Johns Hopkins University (International Foundation for Telemetering, 1971-09)
    • Digital Filtering Techniques for X-Ray Image Enhancement

      Hall, E. L.; University of Missouri-Columbia (International Foundation for Telemetering, 1971-09)
      Image enhancement techniques are designed to improve image quality for human viewing and are especially important in X-ray imaging systems since radiation levels must be minimized. Recursive spatial digital filtering and gray level transform enhancement techniques which may be implemented with small memory requirements and fast computation times will be described. A comparison of computations shows that this method is competitive with fast transform methods in terms of the number of computations and advantageous in terms of memory requirements. The most common method for evaluating enhancement results is subjective human evaluation. An experimental comparison of subjective evaluations and some objective measurements for a series of chest X-rays illustrate the evaluation problem and a possible solution.
    • Measurement and Analysis of Urban Radio Channels for Communication System Design

      Frasco, L. A.; Goldfein, H. D.; U.S. Department of Transportation (International Foundation for Telemetering, 1971-09)
      This paper outlines a program to measure VHF and UHF urban radio channels for playback and analysis in the laboratory. These measurements are required for the design of high data rate communication equipment which makes efficient use of the radio spectrum. We include in this category data communication and surveillance equipment necessary to meet the demands of the variety of command and control functions envisioned for transportation systems by federal, state, and local governments. Included in the paper is a qualitative description of the channel followed by a discussion of the measurement techniques and hardware that will be used. The goal of the measurement program is to develop both analytic and experimental tools for the design and evaluation of advanced communication techniques specialized for signalling over the urban radio channel. These techniques will include modulation waveform design, coding, and the design of receiver structures including those which adapt to measured channel behavior. Future technology will permit complex hardware designs to be used in the implementation of these techniques while maintaining low system cost. The same techniques and approach used here for the urban channel can be applied to other radio channels that occur in transportation systems. In particular, they are applicable to data links for air-ground and high speed ground transportation system uses.
    • Microwave Crash Sensor for Automobiles

      Holmstrom, F. R.; Hopkins, J. B.; Newfell, T.; White, E.; U.S. Department of Transportation; Lowell Technological Institute (International Foundation for Telemetering, 1971-09)
      A prototype microwave radar anticipatory crash sensor for automotive applications is described. This system is for prospective use in conjunction with passive occupant restraints--protective devices that require no action on the part of the occupant to insure their effectiveness. Appropriate antenna configuration and circuitry permit position, velocity, and size discrimination of the target in a simple manner. Results of field tests are discussed, including the manner in which system parameters and target characteristics relate to the tradeoff between false alarm rate, miss rate, and system complexity.