• 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.
    • 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.
    • MAP, A Modular Design Concept for Recoverable Scientific Rocket-Borne Experiments

      Wright, W. W.; Southwest Center for Advanced Studies (International Foundation for Telemetering, 1969-09)
      A series of scientific payloads have been built and flown aboard Nike Apache Rockets. During the design phase heavy emphasis was placed upon realizing a modular configuration both structurally and electrically. The payload was divided into two sections according to functions. The support section included such things as telemetry, batteries, power supplies, timing, aspect sensing and programming facilities. The experiment section was composed of six independent experiments each provided by a different group. Each experiment was built to conform to the shape factor, and electrical requirements of the payload. This paper will discuss the modular nature of the experiments only. The theoretical and instrumental features of the different experimental problems are to be published in other literature along with the research results from the 1969 flight program. The features of the support system which make for maximum modularity will be emphasized in this paper.
    • 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.
    • 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.
    • The High Speed Tape Transport

      Isabeau, John G.; Vogel, Charles A.; Newell Industries, Inc. (International Foundation for Telemetering, 1969-09)
      The Newell tape transport principle is used in instrumentation recorders to currently provide upwards of 56 minutes of recording with 15 MHz bandwidth. Bandwidth several times as wide are definitely feasible. The main characteristic of the tape transport is that it permits precise tape handling at speeds up to several thousand inches per second. The paper discusses the results of research on the basic transport system: the phenomenon of progression at the capstan-tape interface, the mechanism of tape flow to and from the reel and around the capstan. The behavior of capstan tires at high speed and the dynamic response of tapes are discussed. The paper is based on considerable experimental data. Several models of high speed machines are shown.
    • UHF TM System Coverage Predictions Over Water

      Wuster, Walter L.; Naval Avionics Facility (International Foundation for Telemetering, 1969-09)
      A portable telemetry receiving station was desired for use in testing a family medium range surface-to-air missiles. It was recognized that the crucial item in a lightweight portable telemetry system at this time is the telemetry receiving antenna. This is a result of the following facts: (1) the amount of transmitter power available from the missile at UHF is limited due to component capability, (2) the amount of power radiated by the missile in a given direction varies widely due to missile antenna pattern lobing, (3) the beam of the receiving antenna is narrow and the antenna size is correspondingly large if the antenna is designed to have sufficient gain to compensate for the reduced dipole aperture at UHF , and (4) the increase in performance possible by reduction of system noise figure is both expensive to obtain and difficult to justify in a noisy shipboard RF environment. An analysis was made of the portable telemetry system including the shipboard antenna and RF path in order to predict the range of coverage as various system parameters differ. This paper details some of the results of this system coverage analysis.
    • A Phase-Locked UHF Telemetry Transponder for Missile Scoring Applications

      Delbauve, J. R.; Naval Avionics Facility (International Foundation for Telemetering, 1969-09)
      The Phase-Locked UHF Telemetry Transponder described in this article is part of the recently conceived Cooperative-Doppler Missile Scoring System. This system obtains the doppler curve of a missile relative to its target, without the use of special scoring equipment in the missile. This is accomplished through comparison of the telemetry information from the missile with a transponded signal from the target aircraft. The transponder is housed in the target aircraft and is responsible for transponding PAM/FM modulation from the telemetry band (2200-2290 MHz) to the scoring band (1760-1850 MHz), while preserving the phase of the modulation during the frequency translation. In order to accomplish this, true phase demodulation of the PAM/FM signal has been achieved through utilization, of the phase-lock technique. Included in this article is an analytical discussion of the phase-lock loop design with derivations of the closed-loop transfer function and response bandwidth; Root-Locus analysis; Bode diagram; and dynamic range and phase response considerations.
    • Transmitter Signal Coupling: DC Versus AC

      Viggiano, A. A.; Lockheed Missiles and Space Company (International Foundation for Telemetering, 1969-09)
      Radiofrequency telemetry systems using digitized data and FM transmitters in missile development tests result in serious loss of data at the receiving stations when the receivers have narrow bandwidth. This problem is related to the capacitive coupling network between data input and the transmitter exciter. The relative merits of capacitive coupling versus DC coupling are discussed in this paper on the basis of Fourier analysis of a series of pulses. It may be observed that the digitized data in the systems studied always manifest a DC component due to uneven distribution of binary digits 1 and 0. This DC component is eliminated by a capacitor coupling, but is preserved with a DC coupling. This paper assesses the effects of the elimination of the DC component on the relative position of the spectrum to the carrier. The discussion draws on the results of a test situation of an actual telemetry system. In this test, two identical telemetry transmitters were used; the only variable was the type of coupling exciter employed. A DC coupling is recommended for the transmission of binary information on an FM telemetry transmitter as a result of this test and analysis. Conditions for the proper use of such a coupling are stated.
    • Appendix A: Eighth Annual Report of the Telemetering Standards Coordination Committee

      Gardenhire, Lawrence W. (International Foundation for Telemetering, 1969-09)
    • Telemetry-Scoring Receivers

      Burgess, Ken; Naval Avionics Facility (International Foundation for Telemetering, 1969-09)
      In order to provide high accuracy telemetry and miss distance data in the 2200-2290 MHz band, improved receiver sensitivity and exceptional frequency stability are required. The higher receiver sensitivity is required due to extended range requirements with an antenna as small as possible. The exceptionally high frequency stability arises from the fact that typical deviations in center frequency during an intercept is in the order of a few KHz out of 2250 MHz. If the frequency stability problem is not handled properly, this information can be distorted to the point of uselessness. Another problem area that arises as a by-product of stability is phase noise in the local oscillators that degrade the output SNR of a quieted receiver. The solutions to such problems are described in the following sections along with the compromises required for operation on board ship.
    • Frequency Diversity for UHF Telemetry

      Lilienkamp, Hugh; Naval Avionics Facility (International Foundation for Telemetering, 1969-09)
      This paper describes the function and design of the CV-2138 (XAN-1) UHF Down Converter developed at the Naval Avionics Facility, Indianapolis, Indiana. This unit is part of the Navy's Tartar, Terrier, Talos missile UHF telemetry/miss-distance information (MDI) system AN/SKQ-2 (XAN-1) now under development at this Facility. The converter, a dual-channel unit, receives signals in the 2200-2290 MHz and 1760-to-1850 MHz bands, and produces IF's of 240-330 MHz and 110-200 MHz respectively. The 1960 MHz local oscillator (LO) frequency, common to both channels, is supplied from a single source.
    • Why Data System Standards

      Poland, W. B., Jr.; Fitzgerald, R. T.; Coates, R. J.; NASA Goddard Space Center (International Foundation for Telemetering, 1969-09)
      This paper discusses some ideas about data system standards which have been developed at the Goddard Space Flight Center (GSFC) of NASA over a period of about nine years, mainly as the result of experience gained in using the Space Tracking and Data Acquisition Network (STADAN), a collection of tracking, command, and telemetry stations for ground support of scientific satellites. The authors have found that the purposes and uses of data system standards are often misunderstood. To aid in clarifying this situation, they have described the growth and current implementation of the working approach to standards at GSFC. This approach is conditioned by the operating environment and by a number of administrative decisions, which are discussed. The areas included in the existing GSFC standards and some of those planned for future coverage are described, and some considerations bearing on the feasibility of combining GSFC and other data system standards are examined.
    • Performance of Partially Coherent Binary Reception

      Okkes, R. W.; European Space Technology Center (International Foundation for Telemetering, 1969-09)
      This paper considers the performance of a partially coherent detector of phase-shift keyed (PSK) modulated binary data, where the receiver's phase reference is noisy and derived from the carrier component of the received signal by means of a narrow band tracking filter (phase locked loop). The statistics of the detector output are derived and the bit error probability is graphically illustrated as a function of the data channel signal to noise ratio, the signal to noise ratio existing in the phase lock loop bandwidth and the phase lock loop bandwidth to bit rate ratio. The results obtained for the single channel partially coherent detector are used to derive the performance of binary data detection after maximum ratio diversity combination of the two video signals, each of them being demodulated by partially coherent detectors.
    • Frequency Diversity for UHF Telemetry

      Kinkead, W. K.; General Electric Company (International Foundation for Telemetering, 1969-09)
      The use of frequency diversity to allow substantial airborne antenna simplification for L and S band telemetry is described. The system is particularly useful on large, spin stabilized vehicles where omni-directional antenna coverage is required. Typical antenna patterns with and without diversity are presented. A systems block diagram showing dual receivers and diversity combiner is also described. A weight tradeoff is presented for diversity versus non-diversity, with vehicle diameter (at the antenna location) as the variable. It is shown that, at S band, for diameters in excess of about 5 in., frequency diversity represents a favorable approach.
    • Recent Developments in Algebraic Decoding

      Chien, R. T.; University of Illinois (International Foundation for Telemetering, 1969-09)
      Recent developments in algebraic coding theory, particularly in the area of decoding techniques, has made the block coding approach much more attractive for practical systems. Advances have been made in decoding algorithms, implementation and software approaches covering such areas as burst correction, random error correction and the correction of multiple bursts. In this paper a review is given on these recent developments from the point of view of applications. These developments shall be discussed with regard to decoding complexity, computational methods, hardware and software considerations, throughput and cost effectiveness tradeoffs.
    • 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)
    • 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.
    • 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.