• 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.
    • 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.
    • Field Testing of Telemetry Systems

      Pickett, R. B.; Vandenberg Air Force Base (International Foundation for Telemetering, 1970-10)
      Tests have been developed and implemented at the Western Test Range for calibration of telemetry receiving systems. The tests serve an additional function as diagnostic aids.
    • 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.
    • 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.
    • 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.
    • Format and Address Equation Generation by Computer

      Leighou, R. O.; Hill, K. H.; Martin Marietta Corporation (International Foundation for Telemetering, 1970-10)
      Addressable remote multiplexed time division telemetry systems are being used more and more. Most of these systems operate with serial addresses generated by a central unit where each data source has a unique address. Thus the address sequence determines the particular format. In one type of system, the address sequence is determined by transfer logic between a counter and an address shift register. It takes several man-weeks of effort to develop a format and the logic equations to implement the address sequence for that format. To avoid this effort, an algorithm and computer program that generates the formats and the logic equations has been developed and is described. The program data inputs are: the basic format configuration of addresses (channels or data sources) per frame and the frames per master frame; and the number and types of channels at each samples per master frame (S/MF) rate. The program outputs are: address assignments by program ID, telemetry formats sequences with program ID, and the set equations for the address output shift register. Several checks are made during the program and if program restrictions are violated or format generation is impossible, error messages are printed and the program may be halted.
    • A Burst-Trapping Code for Feedback Communication Systems

      Weinstein, S. B.; Bell Telephone Laboratories, Inc. (International Foundation for Telemetering, 1970-10)
      Many data communication channels are perturbed by "bursts" of noise separated by long intervals of comparatively low noise level. The block code described in this paper, a modification of the forward-acting scheme of S. Y. Tong, retransmits information which has been damaged by a noise burst in place of the parity-check digits of future blocks. The responsibility for error detection and correction is divided between the receiver and (via the feedback channel) the transmitter in such a way as to maximize the defense against both noise bursts and the occasional random errors between bursts. There is a fixed delay for decoding, in contrast to the variable buffering delay of ordinary retransmission-request systems. As a result, storage requirements are minimized and there is a constant throughput rate. The feedback channel can incorporate as much delay and be as noisy as the forward channel without significantly impairing performance. Simulation results are provided to illustrate the performance.
    • Instrumentation Systems Engineering Management

      Warren, J. R.; Norton Air Force Base (International Foundation for Telemetering, 1970-10)
      Examples of practical, effective, tools for the management of systems engineering have been presented. The usage of those tools is further examined. Management, as used here, pertains to the technical management of the systems engineering Job. The techniques described are structured around a medium/large data transmission/ acquisition/processing system. The principles can be applied to other systems also. Fundamental to the discussion is the use of models, criteria, and selected data for evaluation which results in decisions and program direction for systems optimization.
    • 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.
    • Apollo Lunar Communications

      Sawyer, Ralph S.; NASA Manned Spacecraft Center (International Foundation for Telemetering, 1970-10)
      The Apollo unified S-band system was developed to handle ranging, telemetry, and voice data using one carrier. Television is transmitted in another mode with the same system. Frequent references are made to the unified S-band system in this report because other systems must work in conjunction with it; however, no description is provided because the S-band system is discussed thoroughly in numerous other reports. The astronauts must coordinate their activities on the lunar surface, and communications are required between them as well as between them and Mission Control Center. A VHF system that has performed excellently in providing voice and telemetry information for lunar-surface use is described in this report. Interest in television has progressed from casual to intense as the Apollo Program has matured; technology has evolved to provide color presentations using the same RF system that was once limited to black-and-white transmissions. The cameras that were developed for both black-and-white and color transmissions are described. Future lunar-surface operations will require traverses too long to be accomplished easily on foot. A system that permits long-range communications from a motorized vehicle on the lunar surface is described. Finally, brief descriptions of several communications-related lunar-environment experiments that have been proposed for the Apollo Program are discussed.
    • 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.
    • Feedback in Data Transmission

      Ebert, P. M.; Bell Telephone Laboratories (International Foundation for Telemetering, 1970-10)
      A survey of the possible gains to be realized by the use of various feedback techniques is given. Noiseless information feedback is considered in detail, and a transmission system for this latter case is given and analyzed. This system is shown to achieve a transmission rate very close to the largest rate possible.
    • Disc Recording: Signal Acquisition and Reduction

      Calfee, R. W.; Data Disc, Incorporated (International Foundation for Telemetering, 1970-10)
      During the last several years, magnetic recording on plated discs has been developed and now can be applied to instrumentation recording. The disc recorder is available in a fixed head configuration for multichannel parallel recording and in a moving head configuration for one or two event parallel recording with extended time. The disc recorder can capture transient analog signals with bandwidth from DC to 6MHz or more for periods of time from microseconds to 20 seconds or more. The analog signal is stored on the disc after being processed through a proprietary period modulator. The disc recorder allows the user a natural base from which to reduce the analog data to computer understood words. Data reduction equivalent to 100 megabit conversion is possible at data rates compatible with the data device. Thus the disc recorder can capture transient analog signals and will allow simple data reduction.
    • Analysis of the Modified Integrate and Dump Decision Device

      Quinn, Mathew J., Jr.; Hayre, H. S.; NASA Manned Spacecraft Center; University of Houston (International Foundation for Telemetering, 1970-10)
      The purpose of this paper is to describe a system which exhibits better bit error rates for Frequency Shift Keying (FSK) signals than those now used to make the bit decision The system is similar to the popular Integrat6 and Dump device., but it is modified to take advantage of the information contained in the FM "clicks" resulting from the demodulation process to aid in making the proper bit decision. The paper is divided into four parts: First, a brief review of the Integrate and Dump Detector is presented. Then the "click" mechanism is described and such properties of this mechanism as the number of "clicks" in a channel are reviewed. Third, a method of using the information in the "clicks" to one's advantage is discussed. Fourth, and finally, the hardware needed to implement such a system is described in general and certain suggestions are made to improve the over-all decision making capabilities of the system.
    • The Upper Bounds of the Confidence Intervals of Bit Error Probabilities Based on a Markov Chain Bit Error Model

      Mizuki, M.; Vandenberg Air Force Base (International Foundation for Telemetering, 1970-10)
      Confidence intervals for the bit error probability of an actual PCM telemetry data can be determined based on the analysis of received redundant bits. The procedure usually requires the assumption of independence of bit errors. However, bit errors may occur in clusters under various conditions of multipath, injection of nonthermal noise of long duration, and bit jitters. As a representation of bit errors in clusters, a Markov chain model is introduced. Some results on the confidence interval of bit error probability are obtained as functions of a Markovian parameter, which designates the degree of departure from the binomial model. The computations are quite laborious compared to the case of the binomial model. This paper gives step-by-step instructions for computing the probabilities that r error bits occur among mn received bits which can then be used for the derivation of the confidence interval.
    • Data Tranmission Over Channels with Noisy Feedback

      Tong, S. Y.; Bell Laboratories (International Foundation for Telemetering, 1970-10)
      A low-cost error control technique is proposed for bulk data transmission with noisy feedback link. The scheme is ideally suited for tape-to-tape bulk data transmission as well as the store-and-forward type of data transmission system. By partition data into superblocks, the technique can be used for any feedback retransmission system. We also show that the scheme can be modified to correct synchronization errors and that noise in the feedback link can be made extremely unlikely to contribute to decoding errors.
    • Telemetry and Communications to Apollo Flight Controllers

      Glines, Alan; Lazzaro, Joseph A.; NASA Manned Spacecraft Center (International Foundation for Telemetering, 1970-10)
      The focus of this paper is on the use of telemetry and communications as essential tools in Apollo flight operations. The operational capabilities of the spacecraft and ground systems are described briefly to provide a background for detailing the management of the Apollo data system. The Mission Control Center is the central point of the operations and the recipient of all real-time Apollo data. Therefore, the operational structure within the mission operations control room is outlined briefly, with emphasis on the flight controllers who are the prime users and manipulators of telemetry data. The Instrumentation and Communications Officer (INCO) and the Operations and Procedures Officer (PROCEDURES) in the mission operations control room are responsible for the compatibility control of both the spacecraft and ground telemetry and communications systems. Their mission duties in four areas are detailed: (1) space-vehicle/ground communications compatibility, (2) telemetry subcarrier and bit-rate control, (3) spacecraft antenna management, and (4) data retrieval. The INCO and the PROCEDURES, through effective management of the many communications-systems modes of operation, maximize the amount of preferred real-time and playback data being transmitted to the Mission Control Center. The importance of the data is illustrated by specific mission events from the Apollo 11, 12, and 13 missions.
    • 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.
    • 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.