• 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.
    • Telemetering in Thermobiology: A Study of Mammalian Hair

      Davis, Stanley D.; Case Western Reserve University (International Foundation for Telemetering, 1970-10)
      An evaluation of the effectiveness of hair as insulation in a cold environment was performed using radio telemetry. Two adult male rats, telemetered for deep body temperature, were placed in an 18°C environment. After five days of monitoring temperature, food intake and body weight, each animal was shaved of all hair and observed an additional five days. Following shaving, both rats increased food intake, lost weight and showed lowered mean daily body temperatures, though in only one was the latter significantly lower. The increased metabolism after shaving was estimated to be between 25.2% and 51.1% greater than the preshave value in one animal, and between 23.4% and 32.9% in the other. The lowest increases were recorded in the rat tolerating the lower mean temperature. On the basis of food intake alone, metabolic demands of the shaven rats at 18°C were shown to be equal that of normal rats at 12°C. The advantages of using telemetry and continuous monitoring of temperature is discussed with regard to the results of this experiment.
    • 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.
    • A Universal L-Band Telemeter for Use on Artillery Projectiles and Gun Launched Research Probes

      Richard, Victor W.; Hadowanetz, Wasco; Aberdeen Proving Ground; Picatinny Arsenal (International Foundation for Telemetering, 1970-10)
      A UHF (1520 MHz) telemetry system for use with artillery projectiles and gun launched research probes is described. The feasibility of a universal telemeter (UTM) is demonstrated which is based on the use of modular plug-in components available to meet a variety of instrumentation requirements, including ogive and rear mounting, thus, eliminating the need for the development of a special projectile telemetry unit for each application of in-flight projectile performance monitoring or gun probe experiment. The special, ruggedized components and techniques for pre-flight high acceleration testing are described. The components described include: broadband, omnidirectional antennas for ogive and base mounting in projectiles; a high gain, all polarization, fan beam receiving antenna; stabilized, high efficiency UHF transmitters; miniaturized voltage controlled oscillators; 8 and 16 channel commutators; button cell and g-activated reserve cell batteries; shock resistant, electrically compatible radome and encapsulating materials; modular assembly cases; and ogive and base mounted telemeter test projectiles. The physical and electrical characteristics of the components of the telemetry system are presented, along with laboratory and field performance data obtained from firing standard, 155 mm, spinning projectiles, including the reception of signals while the projectile is in the gun barrel.
    • 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.
    • Use of an Error Model and a Simulation Program to Support Technical Management

      Brown, L. O.; Baum, R. F.; TRW Systems (International Foundation for Telemetering, 1970-10)
      This paper contains a discussion of various computer programs and their interconnection with an "error model" which have been developed and are being used by TRW, to form a very useful tool for technical management of a missile development and testing program. General aspects and requirements of the simulation and of some subroutines are outlined. A review of possible error sources is made emphasizing their effect on the frequency tracking performance of a typical instrumentation system such as the FPQ-6 radar operating with a radar transponder installed on the target.
    • VHF/UHF Antenna Calibration Using Radio Stars

      Taylor, Ralph E.; Stocklin, Frank J.; Goddard Space Flight Center (International Foundation for Telemetering, 1970-10)
      This paper describes a stellar calibration technique, using radio stars, that determines receiving system noise temperature, or antenna gain, at frequencies below 500 MHz. The overall system noise temperature is referenced to radio star flux densities known within several tenths of a decibel. An independent determination of antenna gain must be made before computing system noise temperature and several methods are suggested. The preferred method uses celestial and receiving system parameters to compute gain; whereas a less desirable method requires an accurately known output level from a standard signal generator. Field test data, obtained at 136 MHz and 400 MHz in the NASA space tracking and data acquisition network (STADAN), demonstrates that antenna gain and system noise temperature can be determined with an accuracy of 1 db. The radio stars Cassiopeia A and Cygnus A were used to calibrate 40-ft. diameter paraboloidal antennas, at 136 MHz and 400 MHz, and phase array antennas at 136 MHz. The radio star calibration technique, described herein, makes possible accurate station-to-station performance comparisons since a common farfield signal source is observed. This technique is also suitable for calibrating telemetry antennas operating in the IRIG 216-260 MHz frequency band.
    • Video Bandwidth, if Bandwidth and Peak Deviation in Notch Noise Testing

      Little, K. G.; Astro Communication Laboratory (International Foundation for Telemetering, 1970-10)
      This paper presents guidelines for conducting notch noise testing of telemetry transmitter-receiver systems. An understanding of the type of FM-FM modulation format which random white noise accurately simulates leads to certain convenient relations between spectral power density, video bandwidth, peak deviation and IF bandwidth. Notch noise measurements were made on video noise in a video limiter to determine the dynamic range required of a system which transmits random white noise faithfully. These measurements were of significant importance because they show that a great deal of excess IF bandwidth is required to transmit random noise spectra. Specifically, it was found that to achieve a 50 db notch noise measurement the system dynamic range may be as much as 10 times greater than the RMS value of the composite signals.