• A Long Term Remote Intragastric pH, Temperature, Motility and Electrical Activity Monitoring System

      Wise, Leslie; Jones, Paul W.; Womack, G. J.; Ballinger, Walter F.; Washington University School of Medicine; McDonnel Douglas Astronautics Company (International Foundation for Telemetering, 1970-10)
      The system under development can monitor intragastric physiological changes over time periods exceeding fourteen days. Prior to this development, long term intragastric measurements were impossible in freely mobile subjects. The electronic instrumentation includes a tethered sensor capsule, automatic titration unit, telemetry system, and data display. The system requires minimal maintenance during the prolonged monitoring period. The sensor capsule utilizes a pH sensitive glass electrode with wet reference, a thermistor, a solid state pressure sensitive transducer, and impedance matching electronics which develop the physically related electrical signals. Signal acquisition is via tether hardline to the multichannel telemetry unit and subsequent RF transmission to a central data receiving system for display and storage. Automatic titration functions, a myograph to record voluntary muscle movement, and the measurement of skin resistance as an indicator of stress, may also be included in the telemetry data. Capsule system tests in vitro indicate these accuracies: ± 0.2 pH units over a range of 1 to 10 pH; ± 0.2°C over a temperature range of 25°C to 45°C; and ± 10% over a pressure range of 0 to 15 inches of water. Life tests of the capsule in vitro show useful life times of the order of 30 days. Preliminary human in vivo experiments have confirmed the capsule sensitivity and stability.
    • The Lunar Communications Relay Unit System Design

      Trachtenberg, B.; RCA Corporation (International Foundation for Telemetering, 1970-10)
      Lunar Surface Exploration by Early Apollo Astronauts was limited by the range capabilities and configuration of the surface communications. To permit greater scientific yield from manned lunar exploration, it was necessary to provide improvements in crew mobility plus communications compatible with extended extravehicular activity. Expansion of EVA and video communications capability was constrained by the requirement of interfacing with existing earth and lunar surface facilities, vehicle payload requirements, and crew operational considerations. Various trade-off s were conducted to permit rapid development of a feasible communication's system which are described herein. The revision of the EVA mission profile necessitated establishment of new signal design parameters compatible with mobile and fixed site relay configurations. The design approach selected required strict discipline to enable integration of the electrical, mechanical, thermal and human factor fields. The resultant design of the Lunar Communications Relay Unit is a portable communications package to provide relay-to-earth of voice, data and color television from lunar surface locations far beyond the LM landing site and relay of ground voice to the EVA crew.
    • Machine-to-Machine Compatability in Wideband recording

      Levy, Avner; Ampex Corporation (International Foundation for Telemetering, 1970-10)
    • Manned Space Flight Network Telemetry System

      Underwood, Thomas C., Jr.; Goddard Space Flight Center (International Foundation for Telemetering, 1970-10)
      This paper discusses the Manned Space Flight Network (MSFN) Telemetry System as it has been developed through the Mercury, Gemini, and Apollo programs and is now being modified to meet Skylab, Earth Resources Technology Satellite (ERTS), and Apollo "J" mission (Apollo 16 and subsequent lunar missions) requirements. The existing telemetry system must be modified to meet the requirements of these future programs. This modification will consist of the implementation of automated configuration switching, centralized control of telemetry subsystems, tunable FM and PSK modulators/ demodulators, high frequency PCM signal conditioners, and the upgrading of both the wide band instrumentation magnetic tape recorders and the PCM decommutation capability. The resulting telemetry system, which will be capable of supporting various manned and unmanned space missions, is described here. Data flow diagrams are delineated and equipment electrical characteristics are discussed.
    • Manned Space Flight Network Unified S-Bond System 1970

      Spearing, R. E.; Goddard Space Flight Center (International Foundation for Telemetering, 1970-10)
    • Micro Miniature Intraoral Telemetry System

      Scott, Ian S.; Ash, M. M.; University of Michigan (International Foundation for Telemetering, 1970-10)
      Intraoral telemetry is often-the only method of evaluating dental problems involving environmentally dependent relationships between occlusion, jaw movements, and the neuromuscular system, and between pH, Eh and bacterial ecology. To study these dental problems a small transmitter (the size of a molar tooth crown) with low power requirements and capable of monitoring eight physiologic parameters has been developed. Such transmitters are now being used to evaluate the design of dental bridges and related neuromuscular dysfunction.
    • A New Comcept for Equalization of Magnetic Tape Reproduce Systems

      Byers, Robert A.; Bell & Howell Company (International Foundation for Telemetering, 1970-10)
      A new approach to the problem of equalizing direct reproduce channels of instrumentation tape recorders has been developed. The technique employed utilizes active circuits and signal processing to develop the required transfer function. The principal advantage of the approach is that it requires only one operational adjustment to obtain the equalization characteristics. This allows a significant reduction in operator setup time and an increase in reliability by the reduction in the number of variable circuit elements. This is achieved by a slight increase in overall circuit complexity, the effect of which is minimized by the repetitive use of simple, functional circuits. The overall system approach is suitable for hybrid or monolithic technology.
    • Noiseless Linear Feedback and Analog Data Tranmission

      Butman, S.; California Institute of Technology (International Foundation for Telemetering, 1970-10)
      It is well known that noiseless linear feedback achieves channel capacity for the additive Gaussian channel. It has also been shown that it can be used to achieve the rate-distortion bound on the mean squared error for an arbitrary Gaussian source sent over the infinite bandwidth white Gaussian channel. However, it is shown here that noiseless linear feedback by itself does not suffice when the channel is bandlimited. It is shown that, out of the more than countable variety of Gaussian sources that ordinarily exist, only a countable subset can be transmitted via the bandlimited noiseless feedback link at the theoretical efficiency predicted by Shannon's rate-distortion bound. Thus, some nonlinear operations are necessary in almost all cases even with feedback.
    • Notch Noise Loading Data on Baseband Tape Recording

      Heideman, W. R.; Nichols, M. H.; Aerospace Corporation (International Foundation for Telemetering, 1970-10)
      Notch power ratio tests were performed on a magnetic tape recorder/ reproducer, using direct recording in the baseband. For the equipment tested, it is concluded that the IRIG method of setting the record power level as that which produces 1% third harmonic on a single tone, does not necessarily result in an optimum record/reproduce cycle. It is concluded that the input and output levels should be set with reference to notch noise test data to optimize baseband tape recording performance for baseband recording of frequency division multiplexed systems. In order to interpret the notch noise data, it was necessary to assume two non-linear processes, one acting in conjunction with the record process and one in conjunction with the playback process.
    • On Linear Information-Feedback Schemes for White Gaussian Channels

      Fang, Russell J. F.; COMSAT Laboratories (International Foundation for Telemetering, 1970-10)
      For the transmission of a Gaussian information source over an additive white Gaussian-noise (AWGN) channel, several noiseless, linear-feedback schemes are shown to be the same in the sense that they not only achieve the rate-distortion bound on the minimum attainable mean-square error (MSE), but also possess identical system parameters. These equivalent schemes can be easily applied to solving the problem of optimally matching a colored Gaussian source with an AWGN channel. These equivalent schemes can further be employed to send messages from digital information sources over AWGN channels. It can be shown that any of these equivalent schemes as a decision-error probability which is the smallest among the class of all linear schemes. The condition of noiseless feedback can be relaxed to cover the more general noisy information-feedback case. A suboptimal scheme is proposed for transmitting data from a Gaussian source, whose output process has a power spectral density function which is uniform in some frequency range and zero elsewhere, over some AWGN channels to some destination. This suboptimal noisy feedback scheme can also be used to send data from a digital information source over an AWGN channel with better performance than can be achieved without noisy feedback.
    • Optical Processing Interfaces

      Shulman, Arnold Roy; Goddard Space Flight Center (International Foundation for Telemetering, 1970-10)
      A brief introduction to coherent optical data, processing is given. Several problems are discussed concerning the implementation of coherent optical data processing for general use. The major problems discussed are concerned with the imaging qualities of coherent systems and the material requirements for recording these images. The solution to several problems is presented and the state-of-the-art in other areas is indicated.
    • PCM Processing in Bandpass Signals

      Shaver, F. H.; Aerospace Corporation (International Foundation for Telemetering, 1970-10)
      Several types of errors are generated when a bandpass analog signal is sampled such that it can be encoded into a sequence of digital words. Two of these types of errors are particularly dependent on the frequency band occupied by the input signal. These are: (1) the aliasing errors due to generation of unwanted spectral components and, (2) pulse width errors due to the use of finite width, flat topped pulses when regenerating-the analog signal. Expressions are presented for the spectral densities and total power of these error sources. The particular dependence of each on the location in frequency of the input signal is investigated and discussed. Quantization noise and distortion due to the smoothing filter which is used to reconstruct the signal are not considered in this paper. It is determined that the aliasing noise power as a function of the ratio of the signal center frequency to the sampling frequency has a series of relative minimums and maximums. A relationship defining the ratios at which the minimums occur is presented. An approximate formulation for the sample pulse width error is presented which allows a simple estimate of its magnitude to be made without knowledge of the smoothing filter transform or the sampling frequency. Quantitative results are presented as a function of the percentage bandwidth of the signal and the ratio of the sample pulse duration to the period of the center frequency of the signal. The results of the analyses are interpreted as design constraints.
    • Performance Evaluation Medthos for PCM Bit Synchronizer/Signal Conditioners

      Peavey, B.; NASA/Goddard Space Flight Center (International Foundation for Telemetering, 1970-10)
      PCM Bit Synchronizer/Signal Conditioners (BSSC) possess 3 basic performance characteristics which directly affect the processing of PCM telemetry data. These characteristics are: bit error rate (BER), bit slippage rate (BSR), and bit sync acquisition (BSA). This paper describes proven methods to meaningfully, and accurately measure these characteristics with particular emphasis on BSR and BSA. These methods require relatively simple and inexpensive procedures and instrumentation, and could be used by manufacturers and users to evaluate and acceptance test BSSC. The basic principle employed in these methods is "fixed threshold frame synchronization" with a unique strategy. Thus, there is no requirement for bit delay between the reference and BSSC output data, and synchronization of the reference data in the comparator with the BSSC output data takes place automatically. Moreover, this approach to testing BSSC represents the actual situation in which the BSSC would be operating as part of the telemetry data system, and hence would provide a direct measure of system performance. In actual application, these methods proved to be very effective and accurate for input SNR of E(b) /N(0) > O dB, and slightly less accurate for E(b) /N(0) < O dB (data having more than 10% errors). In general, BSA and BSR measurement accuracies of 20-30 bits can be achieved. A detailed discussion of accuracy is presented in the paper. In addition, the BSR and BER measurement methods are applicable to assessing the performance of tape recorders (TR) as it affects the actual system performance, rather than just the peculiar TR characteristics of TBE (time base error), bit dropout, and wow and flutter.
    • Pre-Emphasis for Constant Bandwidth FM Subcarrier Oscillators for FM and PM Transmitters

      Campbell, Allan; Sandia Laboratories (International Foundation for Telemetering, 1970-10)
      This paper shows that the proper pre-emphasis for the inputs of constant bandwidth subcarrier oscillators into an FM transmitter is a straight line through the origin, and into a PM transmitter is one of equal amplitude for all subcarrier oscillators. The proper method for calculation of the pre-emphasis for a mixture of channel bandwidths is to use the square root of the bandwidth ratio of the subcarrier channels for both FM and PM transmitters. Examples are given.
    • Processing of NRZ PCM from 10 MB/Sec to 200 MB/Sec

      Gray, J. S.; Radiation Systems Division (International Foundation for Telemetering, 1970-10)
      The type of functions required to optimally process PCM plus noise are the same at low and high bit rates. At high bit rates there are severe constraints in synthesizing these functions due to limitations of present day devices and logic; and due to extrinsic effects of networks over broad baseband bandwidths. Techniques developed for signal conditioning, bit synchronization, group synchronization, and decommutation of NRZ PCM from 10 Mb/sec to 200 Mb/sec are presented. Multiple techniques were investigated in each area over the complete bit rate range of interest to ascertain performance versus complexity and cost effectiveness among different techniques at different bit rates.
    • A Projectile Telemetry System for In-Barrel Data

      Bentley, R. D.; Ruttle, C. J.; Sandia Corporation (International Foundation for Telemetering, 1970-10)
      Sandia Corporation is developing a projectile telemetry system and required ground support to monitor the performance of components mounted in a 155 mm projectile. The telemetry system is to provide the data link required to monitor component performance during and following launch from a 155 mm "long-tom" cannon. The projectile experiences a 16,500g setback acceleration of 15 msec duration coupled with an angular acceleration of 328,000 rad/sec². A P band FM/FM telemetry system has been developed to provide a data link while the projectile is in the barrel as well as out of the barrel. The technique has been successfully tested in a 155 mm projectile with a setback acceleration of 12,500g 20 millisec duration and in a 81 mm mortar round with a setback acceleration of 7,000g 7.5 millisecond duration. A parachute recovery system is used to obtain a "soft" recovery of the 155 mm projectile mounted components and telemetry system.
    • Quartz Crystals Units for High G Environments

      Bernstein, M.; U.S. Army Electronics Command (International Foundation for Telemetering, 1970-10)
      Quartz crystal units are commonly used to achieve frequency accuracy of the order of 100 parts per million or better. The usual crystal mechanical environments are quite benign compared with those encountered In high g telemetry, however, and the normal shock tests are only 100 g's. The preliminary, design of a ruggedized high frequency crystal unit is shown as well as test date on the behavior of these units when subjected to 15,000 g's of impact shock. A crystal resonator is quite fragile since at 20 MHz an AT resonator is only 3 thousandths of an inch in thickness. Higher frequency units appear to have a g limit only slightly in excess of 20,000 g's. At lower frequencies, the resonator is not the limiting element but the supports and bonds become unreliable. A trade-off must be made between a very stiff support, which will increase the acceptable g level, and the concomitant frequency instability due to changes in mechanical stress on the quartz resonator. These stress changes can be caused both by differential thermal expansion of the mount and quartz as well as by shock Induced effects.
    • Signal Designs for Apollo Scientific Data Systems

      Hood, B. H., Jr.; Dawson, C. T.; Loch, F. J.; NASA Manned Spacecraft Center (International Foundation for Telemetering, 1970-10)
      The Apollo lunar-exploration missions are being planned for the purpose of obtaining comprehensive scientific data. The system descriptions and key signal-design considerations for two data transmission systems - the Phase II Scientific Data System and the Particles and Fields Subsatellite - are discussed. In both cases, the designs are constrained by the requirements to (1) use the existing spacecraft systems where possible, (2) use the existing ground stations, and (3) maintain the existing Apollo communications capabilities.
    • Studies of Life Before Birth

      Mackay, R. Stuart; Boston University Medical School (International Foundation for Telemetering, 1970-10)
      By surgical procedures, small physiological monitoring transmitters are placed within the body of fetal animals within the uterus of the mother. After a brief recovery period, various parameters are followed before, during, and after birth, the little animals being born with functioning transmitters already in place. The purpose of such studies is to determine normal values of various cardiovascular parameters in relatively undisturbed subjects and also to follow surgically-produced anatomical and physiological defects which mimic congenital embryologic abnormalities with the goal of learning to cope with these through fetal surgery. Transmission of fetal vectorcardiograms and intrauterine pressure will be described.
    • Synchronization of Pseudo Noise Sequences for PCM Testing

      McClellan, Wade C.; Nichols, M. H.; White Sands Missile Range; Duke University (International Foundation for Telemetering, 1970-10)
      Coherent and noncoherent methods of synchronizing PN sequences for testing PCM telemetry receiving stations are compared. Test results are given for each method using a typical range S-band receiver, bit synchronizer and tape recorder. Effects of time-base-error from the tape are calculated and checked by test results. The laboratory tests indicated that for bit-error probabilities less than 0.01, the noncoherent synchronizer functioned satisfactorily.