• 10.6 Micron Laser Communication Experiment for ATS-F and ATS-G

      McElroy, J. H.; Richards, H. L.; McAvoy, N.; McGunigal, T. E.; Richards, W. E.; Yagelowich, H.; NASA Goddard Space Center (International Foundation for Telemetering, 1969-09)
      A laser communication system weighing 30 pounds and consuming 30 watts is to be flown on the ATS-F satellite for a space-to-ground experiment. An identical system proposed to be flown on ATS-G will complete an experimental intersatellite communication link. A 6-inch aperture optical antenna with a 92 dB antenna gain and a 500 mw carrier provide a minimum 23dB carrier-to-noise ratio for a 5 MHz bandwidth system. This experiment will permit analysis of laser Communication system parameters as a base line for future operational system designs, such as could be employed on a Data Relay Satellite. In addition to the NASA ground station, a station prepared by Bell Telephone Laboratories will perform atmospheric propagation experiments on the beam received from the satellite.
    • A 17:1 Dual Band Circularly Polarized Focused Two-Channel Monopulse Tracking System

      Lantz, Paul A.; Chadwick, George G.; Hurlburt, Roderic W.; Yaminy, Roger R.; NASA Goddard Space Center; Radiation Systems, Incorporated (International Foundation for Telemetering, 1969-09)
      This paper describes a dual circularly polarized feed system for operation In incremental bands over the frequency range from 136 to 2300 MHz. The characteristics of a 60-foot parabola excited by the feed system are discussed. Tracking data for this system have also been obtained using a helicopter, the Apollo VIII vehicle, and Cassiopeia A. It will be shown that the two-channel monopulse technique allows the use of antenna feeds which, in turn, provide sidelobes of greater than -20 db relative to the main lobe peak for all frequencies. This sidelobe performance reflects the fact that the feed is approximately focused at all frequencies, unlike its earlier log periodic type predecessors. The characteristics of a similar feed used in the Apollo Range Instrumented Aircraft (A/RIA) will also be described in this paper.
    • Antenna Pattern Analysis - A Computer Model

      Wolff, F. M.; Atlantic Research Corporation (International Foundation for Telemetering, 1969-09)
      This paper describes a digital computer program which is used to calculate certain performance parameters for a telemetry antenna on a flight vehicle. Ground tests of the antenna, or its mockup, are performed and readings taken of the observed gains. This gain pattern is in the form of paper tape which is converted to a computer, acceptable punched are format. The program was written for the IBM 360/65 computer operating under multiprogramming with a variable number of tasks. A visual representation of the pattern is presented and radar tracking site information is displayed in tabular form. Examples of predicted data and flight data are shown.
    • Apollo ExtraVehicular Communication Telemetry Subsystem

      Weippert, J. J.; Donaghy, R. E.; Sonex, Incorporated (International Foundation for Telemetering, 1969-09)
      The original Apollo Space Suit Communications System (SCC) was designed to accommodate one Extravehicular Astronaut. Early in 1967, NAS.N established a requirement for an extravehicular Communications System (EVCS) which would enable two astronauts to simultaneously explore the lunar surface. Included in this requirement was a telemetry subsystem to monitor the performance of the portable life support system (PLSS), space suit performance and body functions of each astronaut while on the lunar surface. This paper reviews the EVCS telemetry subsystem design including electrical and functional capability, packaging techniques, reliability and configuration control programs utilized in meeting the stringent requirements of a miniature, high reliability, man-rated electronic system for space applications.
    • Appendix A: Eighth Annual Report of the Telemetering Standards Coordination Committee

      Gardenhire, Lawrence W. (International Foundation for Telemetering, 1969-09)
    • Application of Non-Linear Encoding to Picture Transmission

      Gardenhire, Lawrence W.; Radiation, Inc. (International Foundation for Telemetering, 1969-09)
      The process of converting nonlinear analog signals to linear digital signals is a type of companding. This process of companding consists of compressing or expanding the dynamic range at the transmitter and restoring the original levels at the receiver. In telephony it is used to account for differences in speakers' voices. A loud voice will not overdrive the channel, yet a soft voice can be heard. In image transmission and processing, companding is even more important because of the nature of image forming. Both natural and photographic image formation are multiplicative processes. In a natural scene, the illumination and reflectance of objects are combined by multiplication to form observable brightness. Since this combining is a nonlinear process, it is important to transform the output to a linear signal at the earliest possible point in the transmission. If linearizing is not done, noise will affect the dark portion of the picture much more than the bright areas. Companding can be accomplished in many ways either by analog or digital method. The most common analog method is the use of log amplifiers with nonlinear amplitude gain. The most common digital technique is nonlinear encoding which performs the companding while the analog signal is being converted to digits. This companding process, when used on the output of a photo scanner, can be used to improve the transmission and reconstruction of digital pictures.
    • Biotelemetry of EKG Signals Within a Small, Closed Chamber

      Carpenter, F. C., Jr.; McDonnell Douglass Astronautics Company (International Foundation for Telemetering, 1969-09)
      A requirement arose for reliably telemetering EKG data from personnel within a closed metallic chamber to a receiver also located within the chamber. Although there is much information in the literature on biomedical telemetry, it generally deals with propagation of telemetry signals in the clinical laboratory or the field; little, if any, pertains to the problem at hand. Analysis of the environment showed that mathematical prediction of the propagation characteristics of the chamber would be difficult, if not impossible, due to its odd interior configuration. An empirical approach was taken. Several system approaches were considered; an FM/AM system and an FM/FM system were built and each evaluated in the actual environment. Data are presented on test results. A successful system is discussed, including a description of the receiving antenna network employed to ensure reception of the transmitted signals regardless of the location of personnel within the chamber. Conclusions regarding the chamber characteristics are given.
    • Coding - An Engineering Tool for the Digital Telemetry Link

      Muller, Ronald M.; NASA/Goddard Space Flight Center (International Foundation for Telemetering, 1969-09)
      Various digital coding techniques are discussed from an engineer's and user's point of view. Each technique is displayed in a uniform way which measures performance against the best possible (Shannon) channel. Encoding-decoding complexity and other "system" merits and drawbacks of each technique are discussed. The reader is introduced to coding by drawing analogies with an everyday and familiar coded communication channel - spoken English. Bit, word and block error detection and correction techniques are then presented. Lastly, a concatenated block code scheme which combines these techniques is developed.
    • A Complementary MOS Spacecraft Data Handling System

      Lesniewski, Robert J.; Link, Fred J.; Goddard Space Flight Center (International Foundation for Telemetering, 1969-09)
      An on-board data handling system for a 1970 earth orbiting spacecraft has been designed and is currently being fabricated using medium scale integration, complementary MOS arrays. This arrangement which interfaces with the spacecraft's cosmic ray experiment will essentially be an engineering experiment. The organization can be divided into several distinct parts: a 512 word by 16 bit memory, a logarithmic data compressor, 5 rate counter/ registers, an address switcher, and a control logic block. The system contains random access 64 bit memory arrays, 8-bit preset counters, and 8-bit parallel load shift registers. The smallest of these arrays contains over 200 active devices. The rest of the scheme is composed of multi-input nand and nor arrays, D type flip-flops, and 7 stage binary ripple counters. Without these MSI arrays the part count would have exceeded 1000, and would require more than one watt of power compared to the complementary arrangement which requires less than 80 milliwatts.
    • Concepts of Integrated Adaptive Data Transmission Systems

      Filipowsky, Richard F.; IBM (International Foundation for Telemetering, 1969-09)
      Telemetry systems require the transmission of information in analog, sampled, and digital forms. There also are requirements for spectrum conservation, for minimum spurious transmission outside the assigned band, and for highest flexibility in multiplexing and in accepting a wide range of sensors. The paper describes the conceptual design of an advanced information transmission system that operates basically in the sampled mode, but that can accept analog inputs through an information compressing sampler or digital inputs by taking one sample of each input bit and making binary decisions in the receiver. The system uses three different encoding processes in an integrated manner. The first encoding process is performed by a redundancy reducing computer-like subsystem called the contractive encoder. Its purpose is to eliminate unnecessary samples while keeping the essential samples at their correct place on the time scale. Repetition of already transmitted samples. or the insertion of samples from other channels will fill the space of samples that have been removed. The second encoding process is performed by a distributive encoder. The purpose of this part of the information processor is the protection of the information against sudden pulsive disturbances. The distributive encoder spreads the information content of each sample over tens to hundreds of other samples in an ordered manner. If, during transmission, one sample or a group of samples is heavily mutilated by pulsive disturbances, the corresponding decoder in the receiver will recover most of the information of these mutilated samples from the other undisturbed samples while spreading the energy of the pulsive disturbances over all samples so that it contributes only a negligibly small error to any one of them. The third encoding process is performed by the modulative encoder. This device has the task of shaping the samples that are produced by the distributive encoder into bandlimited waveforms so that a noise-like, bandlimited composite transmission signal with a uniform spectral distribution is finally fed into the communication channel. Many adaptive features and the option to use a return channel for repetitions of blocks of samples give the system high stability, high efficiency, and low error ratio.
    • Cosmic Ray Experiments Source - Encoding in the IMP-1 Spacecraft

      Cancro, Ciro A.; Janniche, Paul J., Jr.; Goddard Space Flight Center (International Foundation for Telemetering, 1969-09)
    • Data Reduction System for the Modular Auroral Probe

      Eaker, N.; Southwest Center for Advanced Studies (International Foundation for Telemetering, 1969-09)
      A data processing system has been developed to process PCM and analog data received from the Modular Auroral Probe series of rocket payloads. The system has been designed to take advantage of the availability of an IBM 360-50 general purpose digital computer with IBM 1827 and 1828 input/output terminals. Utilizing a general purpose computer which has the above mentioned terminals has resulted in a minimum cost in new equipment required to perform the processing operations.
    • Digital Time-Base Error Compensator for Wideband Telemetry Recorder/Reproducers

      Klein, M. S.; Tomback, S.; Communications and Systems, Incorporated (International Foundation for Telemetering, 1969-09)
      An advanced development model of a telemetry predetection recording error compensator was designed to reduce flutter and time displacement errors in magnetic tape instrumentation recorder/reproducers so that the final intra-channel timebase error (TBE) does not exceed ±0.1 μsec. The device will operate with recorder/reproducers having bandwidths up to 1.5 MHz and as much as a millisecond of TBE. The incoming waveform is sampled, digitized, and stored in a memory on a recorded pilot tone at a rate determined by the flutter, using phase-lock techniques. Subsequent readout of the memory, composed of MOS shift registers, at a synchronous rate, produces a replica of the playback waveform with wow, flutter, and TBE significantly reduced. This technique offers the following advantages over other approaches: direct delay/BW trade-off (i.e. , 1 msec TBE correction at 120 ips, 2 msec TBE correction at 60 ips, etc.), small size, lightweight, low power requirements, and extensive use of MOS and IC devices, amenable to future LSI construction.
    • Doppler Jitter Versus Digital Error Rate

      Weber, C. L.; University of Southern California (International Foundation for Telemetering, 1969-09)
      In the design of digital communications systems, the error rate is the criterion which is invariably emphasized. In many digital systems, however, there is relative motion between transmitter and receiver which must be controlled by making use of Doppler frequency information. A coherent digital system is herein modeled, in which the trade-off that exists between Doppler measurement capability and subcarrier demodulation error rate is quantitatively presented. System parameters which effect only one of the two above criteria are initially optimized. The dependence of performance on the remaining system parameters is then analytically and graphically presented.
    • Evaluation of Protective Masks by Use of Radio Telemetry

      Redd, R. J.; Defense Development and Engineering Laboratories (International Foundation for Telemetering, 1969-09)
      A telemetering system developed to enable research and development personnel to evaluate physical performance aspects-of US Army protective masks on a quantitative basis is described. Respiration, acceleration, and temperature data generated by a subject wearing a mask can be monitored simultaneously at a point remote from the mask wearer. The system operates in the 216-235 MHz telemetry band using an FM/FM mode. Data transmission in excess of 1/2 mile (via ground wave) has been obtained without experiencing signal deterioration. Data generated can either be recorded directly on a strip chart recorder, magnetic tape recorder or both simultaneously. Data recorded on magnetic tape can be analyzed by use of an Analog Computer. Measurements obtained using this equipment compare in accuracy with that obtained through use of conventional laboratory instrumentation.
    • An Exact Solution of Injection-Phase-Locking

      Wang, C. C.; TRW Systems Group (International Foundation for Telemetering, 1969-09)
      Recent advances of solid-state device technology of generating microwave power from low voltage dc power in one step have renewed interest in the study of injection locking. The solid state millimeter-wave devices have many potential applications such as parametric amplifier pumps, transponder sources, local and self-test oscillators, and high bit rate millimeter-wave repeater systems. The purpose of this article is to solve the nonlinear differential equation of injection locking. Using the method of Riccati's equation, an exact solution has been obtained which is much simpler and more explicit than that shown by Mackey. This article shows the tracking and acquisition behavior of the loop for different initial phase offsets and for different ratios of initial frequency offset D to loop gain B. It also compares the transient and steady-state responses with the exact solution and the linear approximation solution. This article concludes that the difference of steady-state responses obtained from the exact solution and the linear approximation solution will be greater if the D/B ratio is greater.
    • Filtering Effects in a Spread-Spectrum Telemetry System

      Harman, W. H.; TRW Systems Group (International Foundation for Telemetering, 1969-09)
      Binary antipodal direct-sequence biphase modulation is employed (for the purpose of interference reduction) over a channel disturbed by white noise and an "external" coherent sinusoidal interference. Before these are added, the signal suffers distortion in the form of linear filtering whose effects are to be determined. The receiver is a coherent "rematched filter" (matched to the distorted signal). The mean and variance of the detection variable are expressed as an output SNR (signal to noise ratio). The variance is the sum of three components: due to noise, external interference, and self interference. Concise formulas for the first two contributions are developed. The third is approximated and found to be quite small in many cases of interest. Results are applied in the case in which the filter has a bandpass characteristic and external interference is dominant. With fixed signal power entering the filter, there is an optimal chip rate above which filter distortion effects increase faster than process gain; the optimal chip rate is approximately equal to the filter noise bandwidth B (Hertz). For an ideal bandpass filter and a single pole bandpass filter, the optimal chip rates are 1.0B and 0.95B, respectively.
    • A Flexible Format Adaptive Telemetry Encoder

      Communications Satellite Corporation (International Foundation for Telemetering, 1969-09)
      The Communications Satellite Corporation is developing the systems design and implementation techniques for a flexible format adaptive telemetry encoder. The encoder design includes wired program options to tailor system capability to mission requirements. on-board data source controlled interrupt of the normal telemetry format for transmission of preprocessed or block accumulated information automatically adapts the telemetry channel to variable data rate sources. Ground command control format modifications provide increased data rate or continuous burst readout of selected data inputs. Distributed commutation is also available for the remote collection of analog and digital data. Extensive use is made of monolithic MSI MOS devices and custom hybrid bi-polar logic arrays in the instrumentation of the encoder.
    • Flexible Format Generator Design Techniques

      Rathbone, W. M.; Lockheed Electronics Company (International Foundation for Telemetering, 1969-09)
      A Flexible Format Generator is described for use in a Manned Spacecraft Data Management System. The design uses a memory for storing and controlling a wide variety of sampling formats. Design techniques and their benefits are discussed. Particular emphasis is placed upon functional organization. Techniques are described for combining truncated relative addresses with Mode Codes and Programming Instructions. Software counters are stressed and close attention is given to Power Strobing. These techniques should find application in a wide variety of data management systems.