• The Detection of PCM/FM

      Schilling, D. L.; Polytechnic Institute of Brooklyn (International Foundation for Telemetering, 1967-10)
      The calculation of the error rate resulting from the detection of PCM/FM is described. Emphasis is placed on characterizing the effect of the FM demodulator (FMD). The works of Schilling(l), Salz(2), and Klapper(3), are summarized and extended to yield error rate expressions when using an FM discriminator, Phase Locked Loop, or Frequency Demodulator Using Feedback (FCF). The "Integrate-and-Dump" and the Filter Detector are compared. The results indicate that in certain regions the error rate is due primarily to "smooth noise", and the FM demodulator followed by a PCM detector yields an error rate comparable to that obtained with a Matched-Filter (MF) detector. In other regions the error rate is shown to be due primarily to the spikes present at the FM demodulator output. The use of "Spike Detection and Correction" is discussed. It is shown that this technique results in reduced error rate in the "spike regions".
    • Single Side Band Translation Techniques for FM Data Acquisition Systems

      Roth, Allen R.; Lear Siegler, Inc. (International Foundation for Telemetering, 1967-10)
      A Single Side Band Data Translator has been developed and used successfully with any combination of reference and data frequencies from 100 Hz to 10 MHz. This translator, consisting of a computer calculated 90° phase difference network and field effect transistor multiplier circuits yielded undesired sideband signals which were at least 50 db below the desired sideband level over an input frequency range of ten to one. The translator was used to implement a system which recorded 75 time-correlated broadband data channels on a single track of a 5 MHz rotating head tape recorder. After de-translation, a signal to noise ratio of 60 db was measured with the recorder by-passed and a signal to noise ratio of 40 db was measured with all channels recorded. This paper presents the results of research carried out under Contract No. N123(60530)51701A sponsored by U. S. Navy.
    • A High Speed 10 Bit D/A Integrated Circuit

      Rudin, M. B.; O'Day, R. L.; Fairchild Semiconductor (International Foundation for Telemetering, 1967-10)
      A new high speed 10 Bit D/A integrated circuit is described as well as the basis for its design. Principal applications are given, notably a successive approximation A/D employing the circuit as its feedback D/A.
    • Delta-T Curves for Measuring Magnetic Tape Link Jitter

      Sos, J. Y.; Poland, W. B., Jr.; Cole, J. M.; Weiss, G.; Goddard Space Flight Center; U. S. Army, Electronics Command; Laboratory for Electronics Research, New York University (International Foundation for Telemetering, 1967-10)
      Magnetic instrumentation tape recording links are usually required to be substantially transparent data channels. One of the most important deviations from this requirement, both in FM and direct recording modes, occurs in the area of time delay error. A method for measuring the root-mean-square time delay error (Δ) between points on a record vs their separation in playback time (T) has been described in the literature (Refs. 1 and 2), but the implications and interpretation of this technique have not been fully developed. This paper derives the theoretical relationships between the Δ-T curve and the autocorrelation function of a pure sine wave recorded on the tape, and uses this correspondence to establish a connection between jitter spectra and Δ-T curves. A simple instrument for measuring these curves with high accuracy is described, and results of measurements made on a number of intermediate-band tape units in use at the Goddard Space Flight Center are presented. These measurements show that a low-mass tape unit may be superior to high mass units by more than an order of magnitude. The utility of the Δ-T measurement technique is discussed on the basis of its direct relationship to PCM and coherent recording applications, and its value as a standard means for evaluating time delay error in magnetic tape links is described. It is also shown that the technique can be used to determine FM modulation index.
    • Analysis of Multiplex Systems Based on Orthonormal Function Groups

      Balas, Mark J.; Harry Diamond Laboratories (International Foundation for Telemetering, 1967-10)
      Linear multiplex systems may be represented as sequential, invertible transformations on a message set. Such transformations are based on orthonormal functions in the Hilbert space of square-integrable functions. Demultiplexing is accomplished with the inner product which results in high immunity to noise and bandlimiting. When the orthonormal functions form a multiplicative group, easily generated pulse functions arise. Methods are presented for determining these function groups and their corresponding algebras which yield simple and useful multiplex systems.
    • Anticipated Problems of Re-Entry Vehicle Telemetry at UHF

      Numrich, Fred H.; General Electric Company (International Foundation for Telemetering, 1967-10)
      Present information on missile range planning indicates that serious UHF telemetry coverage problems are likely to occur during reentry of ballistic vehicles. Flight test experience at VHF has demonstrated that receiving stations experience difficulty in tracking re-entry vehicles under conditions of rapid changes of signal strength caused by combinations of vehicle motion, vehicle antenna pattern, and plasma attenuation. Similar but greater variations at UHF coupled with narrow beamwidths and reduced sensitivity of re-entry stations portend greater problems at UHF. Conical scan systems may prove inadequate. Comparisons of similar telemetry systems at VHF and S-band are presented, demonstrating that received signal to noise ratios at re-entry stations will be 3 to 9 db below levels Presently obtained at VHF for reentry stations. The narrow antenna beamwidths (1° to 3.5°) will also cause problems in acquisition so that some form of acquisition aid will be required at each station. Omnidirectional antennas currently used in aircraft at VHF will be useless at UHF. Ships and aircraft will require stabilized or compensated antennas. Acquisition of hypersonic targets will be a particularly severe problem for aircraft receiving stations. In addition to defining the re-entry problem, system limitations, and expected effects, this paper also makes recommendations to range planners and users to minimize or correct the anticipated problems.
    • Telcom-Time Variable Telecommunications Performance Prediction Program

      McQuaid, B. L.; Fashano, M.; Hughes Aircraft Company (International Foundation for Telemetering, 1967-10)
      The TELCOM program has been developed to aid in the design and analysis of spacecraft telemetry and communication systems. Given a spacecraft trajectory, it is often desired to predict the total received power of the transmission link. Since the gains and losses of the individual link components are dependent on the spacecraft trajectory, as well as the spatial orientation of the spacecraft, the received signal power varies as a function of time along the flight path. TELCOM organizes the time variable information and calculates the received signal power in the subcarrier and/or carrier predetection bandwidths at specified time intervals. The spacecraft trajectory information and. antenna gain contours are stored on magnetic tape. The time in-variant quantities are provided by the user so that he may easily make parametric studies to determine the effect of link constants on system performance. TELCOM output options include printed values of received signal power at specified. time intervals, plots of signal power, range, look angle versus time, and DB margin summaries at specified points along the trajectory.
    • An Integrated 16-Channel Differential Analog Multiplexer

      Rudin, M. B.; Botchek, C. M.; Rotunda, R. F.; Fairchild Semiconductor (International Foundation for Telemetering, 1967-10)
      The salient characteristics of a multi-channel differential MOS analog multiplexer are presented and compared with the requirements of time division telemetry systems discussed in the paper, "A Family of Linear Integrated Circuits for Telemetry," by M. B. Rudin and R. L. O'Day. Particular emphasis is given to the more important terminal parameters -- channel R(on) variation, switching speed, channel leakage and crosstalk, protection against spurious signals, and power supply requirements. It is shown that this type of design is acceptable for both high and low level signals. The MOS supply levels are special, and some speculation is presented on how future designs could use supplies more compatible with bipolar needs.
    • An Experimental Evaluation of PAM-NRZ/FM

      Heberling, E. D.; Naval Ordnance Laboratory (International Foundation for Telemetering, 1967-10)
      The results of a hardware evaluation of PAM-NRZ/FM are presented along with a description of the conditions under which the data were taken. State-of-the-art commutators, transmitters and receivers procured from commercial sources were utilized in the evaluation tests. The principal characteristics of PAM-NRZ/FM considered were data channel response, performance at low signal-to-noise ratios compared to equivalent FM/FM and PCM/FM systems, linearity, crosstalk, overmodulation, transmission noise, data resolution, decommutator synchronization and a comparison of performance at commutation rates of 25,000, 100,000 and 250,000 samples per second. The test data indicates that PAM-NRZ/FM is capable of 2 to 5 percent data transmission accuracy and that performance at low RF levels is comparable to that of FM/FM or PCMJFM under the test conditions specified.
    • Some Analysis of the WSMR Test Results on DSB

      Nichols, M. H.; Duke University; Duke University | White (International Foundation for Telemetering, 1967-10)
      The purpose of this paper is to relate results of ref. (1), the previous experimental paper, Double Sideband Suppressed Carrier System, by F. J. Schmitt, to theory and to the application of DSB/FM to wideband vibration type data. Inasmuch as the notch noise test was one of the basic tools for the laboratory investigation, the notch noise results and the DSB results are compared. Preliminary data on the effects of tape recording, including flutter, are discussed. Comparison of CBW FM/FM and DSB/FM for vibration telemetry is made on the basis of requirements outlined in ref. (2). The experimental data indicate a 13 to 18 db carrier power improvement of DSB/FM over FM/FM. Reasons for this improvement are given.
    • Adaptive PCM Pattern Synchronization

      Van de Houten, R. S.; Dynatronics, Inc. (International Foundation for Telemetering, 1967-10)
      The trend toward more automated PCM decommutation systems demands less operator intervention in their operation. A weak link in this progression has been in the implementation of group synchronizer strategy. A new synchronizer has been developed based on the optimum properties of sequential probability ratio testing which requires only one program based on required worst case decision error probabilities and which is independent of the PCM format being synchronized. A mathematical model is formulated which accurately describes the operating characteristics of this technique. These operating characteristics are then compared to conventional synchronizer characteristics which demonstrate the superiority of this approach. The decision process described inherently adapts to signal conditions by making decisions faster and with less chance of error as bit error rate decreases. Only the Check Mode is discussed, but the same techniques apply to the Lock Mode.
    • Carrier Synthesis from Perturbed DSB/SC Signals

      Simpson, R. S.; Tranter, W. H.; University of Alabama (International Foundation for Telemetering, 1967-10)
      In suppressed-carrier AM-baseband systems, the process of synthesizing carriers necessary for demodulation usually constitutes a difficult problem, especially when noise or recorder flutter is present. In this paper a particular scheme1, which synthesizes a demodulation carrier directly from a DSB/SC signal, is investigated for the purpose of determining the effect of noise and recorder flutter upon each of the various elements in the carrier synthesis loop. Curves are presented which illustrate the relationship between phase error in the demodulation carrier and various system parameters.
    • Optimum Telemetry for a Meteorological Platform

      O'Bryant, Richard; Hoover, Wayne M.; Sharpe, John H.; Texas Instruments Incorporated (International Foundation for Telemetering, 1967-10)
      In order to predict the large-scale elements of the atmospheric circulation, measurements must be made on a global scale. One such method of measurement involves the telemetry of meteorological data from balloons floating at a constant level over the earth. The balloons are interrogated and their data relayed through a synchronous satellite to a central ground station. A study, funded by the Environmental Science Services Administration, has been made to determine the optimum electronics, in the sense of low cost, for the interrogation and telemetry systems within the constraints of minimum weight and power. This paper presents the problems of such a system, the approaches to the selection of an optimum system, the system selected, and a discussion of the implementation of the electronics of the selected system.
    • Automatic Real Time Data Quality Analysis

      Williard, Merwin W.; Symetrics Engineering (International Foundation for Telemetering, 1967-10)
      This paper deals with methods of detecting and displaying the quality of received telemetry data automatically and in real time. The most commonly used forms of telemetry multiplexing are considered in detail-with reference to application of the techniques to other similar forms of multiplexing. This paper is a result of a study -and hardware development which resulted in equipment now at Cape Kennedy and capable of detecting and displaying bit error rate on PCM telemetry, percentage of channel error on PAM and PDM telemetry and signal-to-noise ratio on FM/FM telemetry. The discussion -is oriented toward the theory of operation and techniques for automatic real time data quality analysis rather than toward the hardware. Methods of detecting and displaying the various data quality indicators is emphasized resulting in conclusions that in many instances relatively reliable data quality indications are possible in real time, but it must be realized that any indication of quality represents a review of conditions of the received signal over some finite averaging interval and thus no measurement can ever provide instantaneous quality indications.
    • UHF Telemetry System Development at White Sands Missile Range

      Chin, Ball; White Sands Missile Range (International Foundation for Telemetering, 1967-10)
      This paper describes UHF telemetry system development at White Sands Missile Range (WSMR), New Mexico, to achieve the telemetry operation change from VHF to UBF. Component and subsystem development is discussed. Results of the S-band equipment testing using the L-20 light aircraft, the F-100F jet fighter, POGO missile, and ATHENA re-entry vehicles are presented. Comparative analysis of missileborne telemetry data transmitted through both the standard VHF and the developmental S-band links are made.
    • Data Collection Station for Automobile Safety Testing

      Goes, Ing F.; Hill, John J.; Volkswagen Works; Defense Electronics, Inc. (International Foundation for Telemetering, 1967-10)
      Increased emphasis on the incorporation of additional safety features in automobile designs has accelerated the adaptation of aerospace telemetry and datahandling techniques to the field of automotive performance testing. Described is a multiple link FM/FM telemetry ground station as used for acquisition of data from an automotive test track. System inputs adhere to aerospace telemetry standards, the output being a computer-compatible digital tape. Detailed attention is given to the high-speed sampling, data conversion, and digital tape formatting subsystem.
    • Ruggedized Quartz Oscillator Crystals for Gun-Launched Vehicles

      Liss, F. T.; Richardson, J. F.; Harry Diamond Laboratories (International Foundation for Telemetering, 1967-10)
      This paper describes a small hermetically sealed quartz oscillator crystal assembly capable of withstanding gun-launch accelerations of 30,000 g and some larger experimental units that have survived accelerations up to 70,000 g.
    • Telemetry of Piston Parameters at Elevated Temperatures

      Slaffer, M.; Admiralty Engineering Laboratory (International Foundation for Telemetering, 1967-10)
      A system is described whereby piston information is continuously monitored using frequency modulation of carriers in the band 2 to 10 mc/s. The basic design of a miniaturised one channel transmit-ter for temperature measurement has been completed and practical details are given in the text. A thermistor was used as sensor. Trials with two operating channels have been carried out on a Lister engine over periods exceeding five hours without component replacement. The choice of high frequency band vras influenced by the desire to avoid the use of an iron cored sensor when the measurement of displacement was to be considered.
    • Performance Standards for Eastern Test Range Telemetry Stations

      Harton, Paul L.; McRary, John W.; Pan American World Airways (International Foundation for Telemetering, 1967-10)
      An extensive engineering effort has been directed toward the rehabilitation of Eastern Test Range telemetry stations during the past five years. Initial planning began, at an earlier date) with studies of range user program plans. These studies have continued throughout the development period to assure a close agreement between range user needs for telemetry data and station capabilities. The plan to rehabilitate telemetry stations on the range has included airborne and shipborne systems, as well as the landbased stations. The stated needs of range users, and the projection of equipment trends formed the basis for specifying new telemetry systems for the Range. Design, production, initial tests, and installation followed in rapid sequence. An evaluation phase was then implemented to determine the operational readiness of the integrated systems and to establish the levels of performance at which each station should be assigned for support. Recent telemetry developments on the Eastern Test Range are briefly described, with emphasis on the launch area telemetry station, Tel 4. This general-purpose telemetry station must be operated in many different modes and configurations to accommodate the various signal structures that are used. Tests that have been used to estimate the station capabilities and limitations when it is configured to receive PAM/FM/FM and PCM/FM links are described as examples of the evaluation concept.
    • Summary and Discussion of Signal-to-Noise Ratio Improvement Formulae for FM and FM/FM Links

      Rechter, Robert J.; Hughes Aircraft Company (International Foundation for Telemetering, 1967-10)
      Frequently, a need exists to compute the postdetection (recovered data) signal-to-noise ratios (SNR) in a given frequency modulated (FM) or double frequency modulated (FM/FM) transmission link; alternately certain postdetection SNR requirements are established, and the link's parameters must be correspondingly specified. In either case, relationships that clearly relate postdetection SNR to link parameters, for either FM (or FM/PM) or FM/FM links, are useful to the telemetr system designer. Although such relationships have been stated in varying degrees of applicability, and rigor of derivation, it has been the author's experience that the sources are scattered, and often not sufficiently explicit. Further, the deviations from the mathematically ideal situation are often overlooked. It is the purpose of this paper to present useful SNR improvement formulae for the general FM and FM/FM case (both for IRIG and non-IRlG multiplexes), and also present data that takes nonideal postdetection filtering into account.