• 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.
    • 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.
    • 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.
    • 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.
    • 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.
    • Effects of Instrumentation Recorder time Base Error on Spectral Purity

      Leeke, P. D.; Minnesota Mining and Manufacturing Company (International Foundation for Telemetering, 1970-10)
      Experimental data is presented to show how carrier amplitude of a recorded signal is affected by Time Base Error. Time Base Error effects on the sideband structure of a recorded signal are also shown for different amounts of Time Base Error and at several frequencies. The effect of capstan servo adjustment on spectral purity demonstrates the need for new methods of performance evaluation to achieve optimum performance when recording spectrum information. The data presented shows that skew (ITDE) has little effect on spectral purity for analysis bandwidths of 50 Hz or greater.
    • Appendix A: Telemetering Standards Coordination Committee Report

      Gardenhire, Lawrence W. (International Foundation for Telemetering, 1970-10)
    • 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.
    • 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.
    • The Implmentation and Utilization of DSB/FM Telemetry Systems

      Johnson, C. S.; Sandia Laboratories (International Foundation for Telemetering, 1970-10)
      Two different double sideband suppressed subcarrier telemetry systems have evolved in the past few years: the harmonic subcarrier method (HSM) and the independent subcarrier method (ISM). This paper provides information pertinent to the implementation and utilization of both systems. The important features of the two systems are discussed by comparing the circuits used in their implementation. Test data is used to illustrate some of the important points about the performance of a DSB/FM telemetry system.
    • 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.
    • Effects of Multipath on Telemetry Data Transmission

      Chen, C. H.; Southeastern Massachusetts University (International Foundation for Telemetering, 1970-10)
      Spurious amplitude and phase modulation effects occur in the received telemetry signal when both the direct waves and the indirect waves enter the receiving antenna. In this paper, a simple multipath model is used which has a single direct wave and a single indirect wave. The indirect wave differs from the direct wave by a time delay and a constant amplitude. With such a simple model, the effects of multipath on telemetry data transmission can be fully examined because of the mathematical simplicity. First an FM system operating above the threshold is considered. The intermodulation distortion and the degradation in the data signal-to-noise ratio due to multipath are both examined. Next we consider two digital systems, namely the noncoherent FSK and the PCM/FM with the discriminator detection. Both systems utilize a split-phase baseband signal. And the error rates depend on the multipath time delay. Comparison is made between the split-phase and the NRZ (non-return-to zero) baseband signals. Available performance improvement from using the predetection diversity combining and the synchronization problem are then discussed. Finally several methods to improve the telemetry data are suggested.
    • 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.
    • FM Distortion Caused by Head-to-Tape Spacing

      Hodder, W. K.; Monson, J. E.; Bell & Howell Research Labs; Harvey Mudd College (International Foundation for Telemetering, 1970-10)
      Although it is well-known that frequency-modulated waves are distorted by systems with non-uniform frequency response, this distortion is difficult to calculate for most systems. The nature of the head-to-tape spacing transfer function allows the development of a closed form solution for FM distortion. Three methods of processing the voltage off the playback head are considered. Integrating the voltage results in amplitude-frequency distortion, but no harmonic distortion. Taking the voltage either directly off the head or differentiating it give both amplitude-frequency distortion and harmonic distortion. Experiments have verified the theoretical results.
    • 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.
    • 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 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.
    • 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.
    • 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.