• 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.
    • 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.
    • Appendix A: Tenth Annual Report of the Telemetering Standards Coordination Committee

      Pruss, Hugh (International Foundation for Telemetering, 1971-09)
    • Applicability of Implantable Telemetry Systems in Cardiovascular Research

      Krutz, Robert W.; Rader, R. D.; Meehan, John P.; Henry, James P.; USAF; University of Southern California (International Foundation for Telemetering, 1971-09)
      This paper briefly describes the results of an experimental program undertaken to develop and apply implanted telemetry to cardiovascular research. Because of the role the kidney may play in essential hypertension, emphasis is placed on telemetry's applicability in the study of renal physiology. Consequently, the relationship between pressure, flow, and hydraulic impedance are stressed. Results of an exercise study are given.
    • Aquatic Mammals - Pinnipedia and Cetacea

      Ray, G. Carleton; Johns Hopkins University (International Foundation for Telemetering, 1971-09)
    • Bias and Spread in EVT Performance Tests

      Smith, Joel G.; California Institute of Technology (International Foundation for Telemetering, 1971-09)
      Performance tests (measurements of probability of error) of communication systems characterized by low bit rates and high reliability requirements frequently utilize classical extreme value theory(EVT) to avoid the excessive test times required by bit error rate (BER) tests. If the underlying noise is gaussian or perturbed-gaussian, the EVT error estimates have either excessive bias or excessive variance if an insufficient number of test samples is used. EVT is examined to explain the cause of this bias and spread; experimental verification is made by testing a known gaussian source, and procedures that minimize these effects are described. Even under these conditions, EVT test results are not particularly better than those of BER.
    • Biomedical Telemetry - A Review and Overview

      Caceres, C. A.; Slater, L. E. (International Foundation for Telemetering, 1971-09)
      Biomedical telemetry has yet to fulfill the high promise generated by its first significant use ten years ago. Most of the progress has been in research biotelemetry; in the monitoring of animal physiology and behavior to gain new insight into both the normal and pathological state. Many clinical applications have developed but few, with the notable exceptions of telephone telemetry systems in cardiology and the monitoring of astronauts, have achieved wide acceptance. The nub of the problem has been the bias in equipment design and system orientation towards research criteria. There is a compelling need and opportunity for telemetric systems specifically designed for clinical, or on-the-spot, use.
    • Birds, Large and Small

      Sladen, W. J. L.; Johns Hopkins University (International Foundation for Telemetering, 1971-09)
    • Characterization and Measurement of Receiver Performance in the Presence of Interference

      Baghdady, Elie J.; Infor Systems, Inc. (International Foundation for Telemetering, 1971-09)
      The performance failure mechanisms of a receiver that may be activated by interference are reviewed and methods of characterizing and measuring this performance to bring out the receiver susceptibility to interference, and the nature and degree of its performance degradation under specified conditions of interference and background thermal-type noise, are presented.
    • Clinical Biotelemetry

      Kilpatrick, David G.; Kilpatrick Associates, Inc. (International Foundation for Telemetering, 1971-09)
      Telemetry and telemetric techniques are of increasing significance in clinical medicine. Diagnostic data is acquired in this way for both manual and automated interpretation or processing. It has become practical to assemble clinical monitoring systems from non-custom equipment. Clinical biotelemetry is reviewed briefly, and a recent composite system is described in some detail.
    • 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.
    • Comparison of Phase Tracking Schemes for PSK

      Cahn, Charles R.; Magnavox Research Laboratories (International Foundation for Telemetering, 1971-09)
      Based on straightforward approximations to evaluate the error rate with phase jitter in the reconstituted carrier and phase slips in the tracking loop, comparison is made of three schemes for biphase and quadriphase data transmission: 1. Track phase on carrier component, 2. Track on suppressed carrier - use differentially encoded PSK, 3. Track on suppressed carrier - retain a carrier component to resolve the inherent ambiguity. For operation at relatively high P(E), as with error correction, schemes 1 and 3 both avoid the inherent degradation of differential encoding; however, both require a relatively narrow band phase tracking loop. Scheme 3, suppressed carrier tracking with ambiguity resolution, achieves the minimum E(b)/N(o) degradation at high P(E) when the loop bandwidth parameter is held fixed by system requirements.
    • Computer Image Manipulation for Restoration and Enhancement

      Andrews, H. C.; University of Southern California (International Foundation for Telemetering, 1971-09)
      This paper briefly outlines a few ideas involved in the use of the versatility of high speed digital computers for natural photographic quality image restoration and enhancement. The subject of image digitization is briefly mentioned followed by three models for image restoration. The linear shift invariant (isoplanatic) model relies on a rich body of knowledge in the form of two dimensional linear systems theory. While the linear isoplanatic model is useful for a variety of degradating phenomena, the linear anisoplanatic and nonlinear models often provide further insight into specialized phenomena. Image restoration may often be followed by enhancement techniques which focus on image manipulations for presentation purposes. The psychophysics of vision play a major role in the development of this aspect as do heuristic techniques which tend to focus on known but often unexplainable human viewing responses. Examples from certain nonlinear enhancement processes are presented.
    • Design of a Memory Controlled PCM System

      Temkin, B. M.; Sherlin, R. E.; General Dynamics Corporation (International Foundation for Telemetering, 1971-09)
      Airborne PCM Telemeters are essentially alike in that they multiplex digital and analog data from numerous sources and format it into a serial data stream. Because of radical format differences in data requirements, however, frequent redesign of format generation logic is mandatory. The recent development of small non-volatile Read Only Memories with large bit capacities has suggested a telemeter whose characteristics can be altered merely by replacing a memory. The authors solution to the problem of the "universal encoder" is the design of the MPS-101 whose word format is controlled by a MOS-FET Read Only Memory. The MPS-101 can store six reasonably complex formats in its 6144 bit plug-in memory card. To insure flexibility, a bit rate oscillator and a premodulation filter are included within the interchangeable module. A program plug enables the user to address (select) the desired format, control the word size, select parity and vary the bit rate. Data rates can be clocked up to 750 KB/S, with no effect on system accuracy. This work has resulted in an encoder whose format is totally arbitrary and whose data structuring and major/minor frame synchronization techniques are strictly under "software" control. This work was performed under Sandia Laboratories Contract Number 72-3233.
    • 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.
    • 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.
    • Digital Transmission Over the RC Channel

      Hoffman, E.; Bell Telephone Laboratories (International Foundation for Telemetering, 1971-09)
      This work evaluates the performance of digital transmission links over a lumped RC channel when one of three static equalization schemes is utilized: 1. Use of a Sidelobe Transmitter 2. Transversal Filter at the Receiver 3. Frequency Compensation of the Transfer Characteristics to form a rectangular Nyquist Channel. The effect on the probability of error of thermal noise and intersymbol interference is considered. In each of the equalization schemes, the intersymbol interference is reduced to zero, and the waveshape at the transmitter which maximizes the SNR at the receiver decision instant is transmitted. It is found that the performance of the Sidelobe Transmitter and the Transversal Filter Receiver are equal theoretically and that Frequency Compensation provides the poorest results. The comparisons carried out in this work have utilized the RC channel as an example. Detailed generalization of the comparative performance as a function of the impulse response of the channel utilized would be desirable but cannot be made readily. An analysis of the coaxial line is planned for the future. The eigenfunctions and corresponding eigenvalues of the system are required in order to evaluate the optimal performance of the Sidelobe Transmitter and Transversal Filter Receiver. For arbitrary impulse responses, these eigenfunctions are usually complex to obtain. However, one is able to state in general that since the Sidelobe Transmitter or Transversal Filter combined with transmission of the optimum waveshape represent the best linear filter, their performance will not be inferior to the Frequency Compensated rectangular Nyquist channel. This follows since frequency compensation networks fall into the class of linear filters.
    • 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.
    • Error Bounds in Coherent Digital Systems

      Prabhu, V. K. (International Foundation for Telemetering, 1971-09)
      We present simple upper and lower bounds to the distribution function of the sum of two random variables in terms of the marginal distribution functions of the variables. These bounds are then used to obtain upper and lower bounds to the error probability of a coherent digital system in the presence of intersymbol interference and additive gaussian noise. The bounds are expressed in terms of the error probability obtained with a finite pulse train, and the bounds to the marginal distribution function of the residual pulse train. Since the difference between the upper and lower bounds can be shown to be monotonically decreasing function of the number of pulses in the finite pulse train, the bounds can be used to compute the error probability of the system with arbitrarily small error.
    • FM/FM Telemetry of Physiological and Force Data During Military Parachuting and During High Speed Aerial Tow

      Reid, D. H.; Doerr, J. E.; Martin, J. D.; Terry, D. M.; Naval Aerospace Recovery Facility (International Foundation for Telemetering, 1971-09)
      15- and 9-channel FM/FM physiological/force-field telemetry data acquisition systems utilizing microminiaturized signal conditioning modules, IRIG subcarrier oscillators and 220 or 1485.5 MHz transmitters have been utilized to monitor the responses of military test parachutists throughout intentional free-fall parachuting and continuously during highspeed (110-150 KIAS) through-the-air-tow by C-130 aircraft. No in-depth physiological studies of parachutists have previously been conducted and no reference to intentional aerial tow of humans was found in the literature. The objective is to provide better human engineered egress and retardation equipment for the aircrewmember, to describe parachutists physiologically, and to assess biomedical response to aerial tow so that mid-air retrieval systems can be developed for rescuing ejectees over enemy territory. Mean heart rate profile to parachuting exhibits a double peaked curve with the highest values near parachute deployment (157.7 BPM) and second highest rates near landing (155.7 BPM) compared with baseline values of 77.4 BPM one hour pre-jump. Respiratory rate more than doubles during the jump (32.1 BrPM) at deployment when compared with baseline conditions (15.6 BrPM). Total riser forces at parachute deployment average 1632 lbs (8.34 +G(z)), Preliminary air tow data indicate that heart rate increases linearly with speed to 150 KIAS. One subject, who averaged 131.5 BPM at landing during nine parachute descents, had heart rates of 128 BPM at egress during tow, 171 BPM at 110 KIAS, and 182 BPM at 150 KIAS. Thermistors and subjective data indicated no significant chilling after 14 minutes in the air-stream.