Now showing items 1-20 of 66

    • International Telemetering Conference Proceedings, Volume 07 (1971)

      International Foundation for Telemetering, 1971-09
    • Appendix A: Tenth Annual Report of the Telemetering Standards Coordination Committee

      Pruss, Hugh (International Foundation for Telemetering, 1971-09)
    • VHF/UHF Stellar Calibration Error Analysis

      Taylor, Ralph E.; Stocklin, Frank J. (International Foundation for Telemetering, 1971-09)
      A statistical error analysis is performed to determine the degree of uncertainty encountered when calibrating steerable VHF /UHF receiving antennas with the stellar calibration method. The analysis considers the propagation of precision error indexes. It is shown that an antenna gain calibration by the stellar method has a one-sigma (1σ) uncertainty of ±0.65 dB at 1440 MHz (L-band), and ±0.8 dB (1σ) at 136 MHz (VHF). Somewhat increased precision can be achieved by monitoring the antenna gain-to-noise temperature (G/T) ratio at a station; a worst-case uncertainty of ±0.4 dB (1σ) can be realized at both L-band and VHF. Finally, field test measurements of antenna gain, obtained at 136 MHz in the NASA space tracking and data acquisition network (STADAN), demonstrate an uncertainty of ±1.0 dB, or less, which effectively confirms the analytical result.
    • 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.
    • 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.
    • Dielectric-Loaded Conformal Slot Antennas for Telemetry Applications

      Jones, H. S., Jr.; Harry Diamond Laboratories (International Foundation for Telemetering, 1971-09)
      The design and construction of a variety of slot antennas that conform to conical, ogival and cylindrical surfaces are described. These antennas are dielectric-loaded cavities or waveguide radiators with very thin metallic walls that are efficient and simple to fabricate. Some are fabricated from low-loss copperclad dielectric materials. Other designs involve the process of electroless copperplating over a dielectric substrate to form the cavity. Radiating slots are cut after the cavity configuration is formed. The feasibility of these antenna designs and the construction methods employed have been fully demonstrated. Many important advantages are derived from the use of the technique. It is highly suitable for the design of telemetry antennas in the L-band region. Antennas of this type lend themselves to flushmounting and can be easily designed to radiate through a dielectric window. Design parameters are easily controlled, thus allowing good overall electrical performance with consistent and reliable results for production quantities. Because they can be constricted to conform to the structures on which they are mounted, very good radiation pattern coverage is obtainable. Most models tested have good voltage standing-wave ratio characteristics and are capable of operating over at least a 101, bandwidth. Complete antenna systems with varied configurations have been designed in the frequency range from 1.0 to 2.5 GHz, yielding highly satisfactory results and at very low cost.
    • 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.
    • 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.
    • High Density Digital Recording with Video Techniques

      Curtis, D.; Rolfe, J.; International Video Corporation (International Foundation for Telemetering, 1971-09)
      A digital recorder which writes or reads digital data at 8 megabits per second and has a storage capacity of 84 billion bits per reel of tape is described. The packing density is in excess of I million bits per square inch on conventional one-inch magnetic tape. The high packing density and transfer rate was achieved through the combination of phase-encoded digital electronics with a helical scan video transport. The use of the helical scan technique permitted extremely efficient utilization of the tape and permitted inclusion of other features, such as high-speed search (400 ips), individually addressable records, and self-threading and cartridge-loading capability.
    • Half Speed Recording with Ferrite Heads and High Energy Tape

      Price, R. L.; Youngquist, R. J.; Minnesota Mining and Manufacturing Co. (International Foundation for Telemetering, 1971-09)
      This paper describes the results obtained with several new techniques which are being used to extend the frequency bandwidth limits and the signal to noise ratios of instrumentation magnetic tape record/ reproduce systems. During the past decade, wideband magnetic tape information recording densities have advanced in several stages to the currently used 60 to 80 micro inch wavelengths. The new techniques described in this paper now make it practical to record and reproduce wavelengths in the order of 30 to 40 micro inches. This results in a frequency bandwidth of 1.0 MHz at a tape speed of 30 inches per second. In comparison with present wideband systems this means an improvement of 2X in bandwidth, or a reduction of tape speed by one half is now possible while maintaining approximately 20 dB broadband signal to noise ratio with a track width of .025 inches. This width provides 28 tracks per inch of tape width. This improved performance has been obtained by combining recent improvements in "High Energy" tape, narrow gap ferrite record heads and ferrite reproduce heads. Using a systems approach, electronic signal processing circuits have been developed which coordinate these improvements in tape and heads, resulting in optimized "high performance" record/ reproduce systems.
    • High Speed, High Density Digital Recording

      Isabeau, John G.; Data Recording Systems, Inc. (International Foundation for Telemetering, 1971-09)
      The wide signal bandwidth attainable with the 960 inch per second longitudinal tape transport, combined with high density recording at about 20,000 bits per inch provide a multichannel 20 Megabit/second recorder with a 64:1 time expansion capability. The tape transport mechanism consists of two solid, flangeless tape packs placed in direct contact with a large capstan. Stability of the tape movement is achieved by use of a control system which provides instantaneous adjustment of the pack contact forces as a function of direction, velocity, acceleration and pack diameter. This results in full versatility when programming the transport motion. The high density digital signal is phase encoded and processed through the recorder as an analog signal, then is demodulated using a phase lock loop to recover the clock. The sample and hold phase comparator controls a VCO at a fixed nominal frequency, followed by a divider. This configuration permits operation at all bit frequencies in a 128:1 range and allows the clock to coast through a 50 bit dropout without bit slip. Demonstrated bit error rate is 10⁻⁶ maximum.
    • 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.
    • 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.
    • 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.
    • 136 MHz Interferometer Error Due to Galactic Nucleus

      Kyriakopoulos, N.; Taylor, R. E.; Reich, R. (International Foundation for Telemetering, 1971-09)
      Spacecraft orbits are determined by means of direction cosines generated from electrical phase data provided by the 136 MHz Minitrack radio-interferometer system. The phase data thus determine the direction cosines of the position vector as the spacecraft passes across Minitrack's fan-shaped antenna beam. Uncertainties introduced into the output electrical phase due to undesirable interfering sources limit the basic accuracy of the Minitrack system. Although a knowledge of the spacecraft orbital dynamics may be used to improve the accuracy of the system, nevertheless there remains a fundamental error due to interference caused by the passage of the galactic nucleus. This paper determines the error due to a distributed noise source. Furthermore, it develops an expression for the lower bound of the phase error when the noise source is not uniformly distributed across a zenith-pointed fan beam. In addition, it determines the threshold of the Minitrack input power levels below which the electrical phase is no longer determined unambiguously. The effect of the passage of the galactic nucleus coincident with the presence of a space craft has been analyzed, and the corresponding phase error determined.
    • Aquatic Mammals - Pinnipedia and Cetacea

      Ray, G. Carleton; Johns Hopkins University (International Foundation for Telemetering, 1971-09)
    • 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.
    • Birds, Large and Small

      Sladen, W. J. L.; Johns Hopkins University (International Foundation for Telemetering, 1971-09)
    • 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.
    • A Shock Hardened Delayed Transmission System for Transient Data Acquisition

      Bentley, R. D.; Fritz, R. L.; Sandia Laboratories (International Foundation for Telemetering, 1971-09)
      A shock hardened, delayed transmission PCM system for use in an artillery projectile instrumentation program is reported. The output of the projectile mounted PCM encoder is coupled to an MOS shift register memory to delay data transmission until projectile flight, thus eliminating the requirement for a real-time transmission link for in-barrel data. The capabilities to monitor both in-barrel phenomena and flight performance parameters are included. Windowing of the transient, in-barrel data is accomplished by threshold discrimination within the projectile mounted system. System design, operation and ground support requirements are discussed with flight test results presented.