• International Telemetering Conference Proceedings, Volume 03 (1967)

      International Foundation for Telemetering, 1967-10
    • Description of Computer Program to Analyze Gain Distribution of an Antenna Pattern

      McQuaid, Bruce L.; Hughes Aircraft Company (International Foundation for Telemetering, 1967-10)
      The gain of a radiating antenna is generally a function of the direction in which the antenna is pointing relative to the direction of the received or transmitted signal. The gain distribution over an imaginary sphere surrounding the antenna is called the antenna gain pattern and can be measured experimentally. Under certain circumstances the tolerances associated with the pointing vector make it impossible to determine the antenna gain precisely but rather circumscribe an area on the spherical surface which include a number of different gain values. A computer program called INTGRT has been developed that will determine from measured antenna pattern data the gain distribution within the uncertainty region and will provide a measure of the probability of the gain being above a certain gain value. The boundary of the uncertainty region is described in terms of the coordinate system used in measuring the antenna patterns. Each gain value contained inside this boundary is compared to some reference gain level and a running total is made of the number of values found to be equal to or greater than the reference value and the total number of values inside the region. After weighting each total by an equal area function, the ratio of the number of values above a reference level to the total number of values in the region gives an estimate of the probability that the gain of the antenna will be equal to or above the reference gain. If the region is analyzed in this way for a number of reference levels, the distribution of gain values within the region is obtained. This information is extremely valuable in determining space communication system performance during periods in which the orientation of the spacecraft's antenna with respect to the earth cannot be determined precisely but is known to be within certain limits.
    • 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.
    • Computer-Controlled Data Compression at 100 KC

      Schoen, Emil; Scientific Data Systems, Inc. (International Foundation for Telemetering, 1967-10)
      This paper describes a real-time computer-controlled telemetry system that can accommodate a 100 kc sample rate. The system's operating structure allows high-speed, asynchronous PCM data to be simultaneously decommutated, compressed, displayed, and merged. Data generated during test firings of the U. S. Navy's Poseidon missile will be reduced and processed by this system. Emphasis of the paper is on a description of the telemetry system's hardware and software.
    • Effects of Random Fluctuation Noise on FM and FDM/FM Reception

      Wachsman, R. H.; Baghdady, E. J.; ADCOM, Inc. (International Foundation for Telemetering, 1967-10)
      A tutorial review and analysis of the effects of random noise upon the output of a conventional FM demodulator is presented. The mechanism by which these effects are produced is conveniently brought out with the aid of phasor diagrams. Illustrative computations are given of the smooth and impulsive components of the output noise and of output signal-to-noise power ratios for various types of frequency modulation. Various types of thresholds are pointed out and the practical significance of threshold reduction as a system design optimization tool is discussed.
    • Phase Linearity in Telemetry Reception

      Ghais, Ahmad F.; Ferrari, Eugene J.; Boardman, Charles J.; ADCOM, Inc. (International Foundation for Telemetering, 1967-10)
      The problem of phase nonlinearities in telemetry-receiving systems is studied. The principal data-degrading effect is shown to be intermodulation distortion of FDM telemetry signals. Another form of data degradation, namely, intersymbol interference in TDM telemetry signals, is found not to be related directly to phase nonlinearities, but rather to the transient response of the receiving system. The noise-loading technique is introduced as an effective means of characterizing, analyzing and measuring intermodulation distortion. Some analytical results are cited relating the amount of intermodulation distortion to signal and receiving-system parameters. Analytical details are omitted, the emphasis being placed on interpreting the significance of the results to the telemetry systems engineer. The experimental verification of these relationships is briefly reviewed. The results are used to establish quantitative tradeoffs between the performance parameters of receiving systems. These tradeoffs are then used in formulating methods of specification and design to ensure high data quality.
    • 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.
    • On-Line computer Monitoring-Immediate Interpretation of the Electrocardiogram

      McAllister, James; Caceres, Cesar A.; Medical System Development Laboratory (International Foundation for Telemetering, 1967-10)
      The purpose of this paper is to provide some insight into the continuous monitoring and computer analysis of medical signals, in particular the electrocardiogram which has been chosen as a model. The advantages of having continuous data analyzed by an accurate, objective system are elaborated. The great mass of data being collected has heretofore been stored and forgotten in many instances but with immediate computer analysis the interpretation of trends and rapid physiological changes are easily and rapidly manifested. In addition, statistical evaluation of the data through programming te techniques can lead to new diagnoses and treatments and allows the monitored data to be compared with "pre-obtained" data as well as other groups of people.
    • A Family of Linear Integrated Circuits for Telemetry

      Rudin, M. B.; O'Day, R. L.; Fairchild Semiconductor (International Foundation for Telemetering, 1967-10)
      Advances in monolithic circuit and process techniques are making available a steadily increasing number of linear integrated circuits especially applicable to telemetry systems. This paper reviews the principal types of telemetry systems--PCM, PAM, PDM, and FM/FM. It demonstrates that a compatible family of monolithic IC's in various stages of development at Fairchild can perform most of the circuit functions required by these systems--namely: (1) signal conditioning amplifiers, (2) multiplexer, (3) sample and hold, (4) unity gain A/D buffer amplifier, (5) A/D and PDM comparator, (6) D/A reference and switches, (7) D/A summing amplifier. In addition, future integration of functions not performed by the above circuits is discussed.
    • A Micropower Low Noise Integrated Operational Amplifier

      Pilling, D. J.; Wilson, G. H.; Fairchild Semiconductor (International Foundation for Telemetering, 1967-10)
      This paper describes a new integrated operational amplifier designed specifically for low standby power consumption. This amplifier is intended for use in portable instrument and telemetry equipment where low battery power drain is an important consideration. This high gain, low power, low noise operational amplifier is fabricated on a single silicon chip. Recent development of a low noise transistor process and a compatible high value resistor process led to its development. The highlights of its performance specifications are its high input impedance, low offset, low noise, and, for the first time in a commercially available operational amplifier, quiescent power consumption in the microwatt range. The circuit has excellent common mode and power supply rejection which, coupled with the high voltage process, insure operation over a supply voltage range of ±2.7 v to ±18 v. The amplifier, as shown in Figure 1, has a differential input and a single ended output. The general parameters of this amplifier are shown in Table 1.
    • A New Concept in Low Flutter High Environmental Recorders

      Hadady, R. E.; Bentley, R.; Kinelogic Corporation (International Foundation for Telemetering, 1967-10)
      To improve the performance of tape recorders operating under severe vibration, acceleration, and shock environments, two new flutter reduction design concepts have been developed: 1. Capstan servoing during the recording process to servo out flutter before it is recorded. 2. A new reel drive system in which the reels are coupled together to minimize tape tension variations and eliminate the possibility of throwing a tape loop. Test data on a prototype spaceborne recorder has proven the validity of the concept. The prototype has shown a capability to reduce flutter by factors ranging from 3 to 10 over conventional high-environrnent recorders. Typical flutter performance figures on the prototype (which accommodates 600 feet of 0.25" wide tape and operates at 30 ips) are: 0.36% p/p to 5000 Hz - on the bench 1.8% p/p to 5000 Hz - under environment (20 g rms random vibration) Time displacement errors (TDE) are ± 3 microseconds - on the bench ± 6 microseconds - under environment (20 g rms random vibration)
    • Double Sideband Suppressed Carrier Telemetry System

      Schmitt, F. J.; Lockheed Electronics Company (International Foundation for Telemetering, 1967-10)
      Vibration, shock, and acoustic data constitute one of the principal requirements for wideband telemetry. In order to permit a quantitative comparison of DSB/FM with the experimental results on constant bandwidth FM/FM for telemetry wideband noise-like data, a laboratory investigation has been conducted at WSMR. This paper reports experimental data on RF spectrum occupancy, intermodulation, performance against thermal noise, and some preliminary data on the effects of tape recording.
    • A Multiple Format Stored Program Data Acquisition System

      Bauer, W. R.; Hodges, G. G., Jr.; Telemetry Systems Department (International Foundation for Telemetering, 1967-10)
      A multiple format telemetry system is described which is flexible enough to be adaptable to many applications. The system incorporates a flexible programmer that utilizes a non-destructive readout memory which operates in conjunction with an external index counter. Subcommutator addresses stored in memory are addressed partially by the index counter and partially by the format instruction. Multiple formats can be generated, limited only by the requirement that the sampling rates in a given format be binary multiples of the slowest sampling rate in that format. The advantage of this programmer lies in the flexibility accommodated, typically, with one or two read-only memory cycles. The remote acquisition units used in the system are flexible in that they can be configured to provide various combinations of low-level, high-level, and bi-level inputs. These units are designed primarily from two large scale integrated (LSI) metal-oxide-semiconductor (MOS) building blocks. One LSI circuit is a sequential multiplexer, which also functions as an analog-to-digital (A/D) converter; the other circuit is a 16- channel random access multiplexer.
    • Theoretical and Experimental Error Rates of PCM Codes

      DeWitt, K. I.; Perez, P. E.; United Aircraft (International Foundation for Telemetering, 1967-10)
      As PCM increases In -use as a method of transmitting data, it is of greater importance to know exactly the probability with which each bit may be received accurately. While most engineers in the field are aware of the basic probability curve for PCM signals, very few are aware of what to expect under the many varied conditions of noise bandwidth, data bandwidth, code type, method of data regeneration and DC offset. These effects are clearly handled in this discussion. The effect of phase jitter, always present in any data regenerating device, is ignored in this presentation, and will ultimately add another element of degradation, particularly at the higher noise levels.
    • Detection of Orthogonal Sine and Cosine Pulses by Linear Active RC-Networks

      Schmid, P. E., Jr.; Nowak, D. J.; Harmuth, H. F.; Allen-Bradley Co. (International Foundation for Telemetering, 1967-10)
      An active RC matched filter, particularly useful for phase-coherent, coded or uncoded, binary or non-binary communication channels, is described. One detector circuit performs the equivalent of two simultaneous cross-correlations, avoiding the need for electronic multipliers, reference wave generation and phase synchronization. For example, only I circuits are needed in a receiver that is required to detect the polarity or presence of an orthogonal set of I sine and I cosine pulses. In view of the circuits realizability with linear IC technologies, the sensitivities with respect to circuit component variations are analyzed in detail. The results of the sensitivity analysis are presented in graphical form. Experimental results confirm the predicted performance; i.e. Q-factors in excess of 4000 were obtained with small, general-purpose operational amplifiers.
    • A Quantitative Impedance Pneumograph

      Bergey, George E.; U.S. Naval Air Development Center (International Foundation for Telemetering, 1967-10)
      An impedance pneumograph capable of quantitatively measuring respiratory volumes is described. Physically, the pneumograph is one of several 3/8 x 5/8 x 7/8 inches modules incorporated in a miniature biotelemetry system, with separate modules being utilized to process signals derived from a number of physiological parameters such as EEG and EKG in addition to respiration. Considerable experimentation was performed regarding optimization of the electrodes used in this impedance pneumograph as well as the frequency and amplitude of the excitation voltage applied between the electrodes. The result was a fairly simple and inexpensive device which uses a higher frequency (300 KHz) excitation voltage than is normally used in impedance pneumography. The two electrodes, constructed of silver coated nylon for flexibility, are insulated from the subject by a layer of polyethylene film, thus forming a capacitive coupling of the electrode to the subject. This technique effectively eliminates changes in skin-to-electrode resistance, largely responsible for baseline drift encountered with previous impedance systems, so that this pneumograph responds only to variations in the actual impedance between the two electrodes. Empirically, a nearly perfect linear correlation was found to exist between the transthoracic impedance measured by this impedance pneumograph and pulmonary volume. The two insulated electrodes are pasteless and therefore easily applicable and non-irritating. They are held in position by an elastic, quick-donning, vest-like garment.
    • A Pulse-Code-Modulation (PCM) Telemetry System Utilizing Multiple Integrated Circuit Technologies

      Fox, D. C.; Autonetics (International Foundation for Telemetering, 1967-10)
      This paper describes a Pulse-Code-Modulation (PCM) Telemetry System contained on a module that is unique in several ways: 1. Uses all Integrated Circuits (Ics). 2. Integrates many IC types and technologies for superior system physical, environmental, and performance characteristics. 3. Multiplexer section: a. Uses one type of IC (MCIS multifunction IC) b. Is bipolar (both positive and negative voltages can be multiplexed) c. Accepts low- or high-voltage inputs (±51.1 mv to ±5.11 v) d. Is extremely small and compact (5 ICs total, provides 48-channel multiplexing) e. Accepts both differential and single ended channels f. Is controlled by random or sequential addressing modes 4. Amplifier section: a. Has high input impedance (100 meg ohms) b. Has high common mode rejection (to 120 db) c. Has gain (1 or 100) d. Has sample and hold capability 5. Analog-to-Digital Converter (ADC) section: a. Is bipolar (both positive and negative voltages can be converted) b. Has high accuracy (10 bits) c. Uses current summation with successive approximation d. Has high speed (up to 1 MHz)
    • 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.
    • 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.
    • 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.