• A Short Range Underwater Biotelemetry System

      Steadman, John W.; Convair Division, General Dynamics (International Foundation for Telemetering, 1967-10)
      The requirement for monitoring the physiological functions of the test subject in weightlessness simulation activities coupled with the advantages of using telemetry for such monitoring led to the development of a biotelemetry system. One valuable technique for simulation of weightlessness uses the neutral buoyancy obtained by having the subject under water, which leads to a requirement that the telemetry system work in this medium. Previous underwater telemetry systems have usually used ultrasonic carriers. The system described in this paper is unique in providing a multiple channel underwater telemetry system using an electromagnetic carrier. The development of transducers used with this system to provide information on the work load Imposed by various simulation tasks is also described.
    • 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.
    • 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.
    • 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.
    • 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.
    • 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)
    • International Telemetering Conference Proceedings, Volume 03 (1967)

      Unknown author (International Foundation for Telemetering, 1967-10)
    • 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.
    • 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.
    • 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.
    • 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 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.
    • 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.
    • Transmission of Direct Blood Pressure from Dogs During Obedience Training

      Rader, R.; Sears, W. J.; Reid, D. H.; Meehan, J. P.; Henry, J. P.; University of Southern California, School of Medicine (International Foundation for Telemetering, 1967-10)
      A method for transmission of direct blood pressure from dogs during obedience training, treadmill exercise and sleep is described. Solid state transducers, 6.5 mm diameter, were implanted in the abdominal aorta of healthy young mongrel dogs. The design of the specialized circuitry required to detect and transmit blood pressure data is presented. Calibration was performed by comparing direct and transmitted data. An obedience training course provided emotional arousal, and for physiological stimuli the animals exercised on a treadmill at various grades and speeds up to exhaustion. Blood pressures taken during natural sleep were defined as basal for each animal. Representative observations are noted to emphasize the practical benefits of advanced biotelemetry in research.
    • On-Line Computer Tuned S-Band Phase-Lock Receiver

      Van Wechel, Robert J.; Counter, James M.; Interstate Electronics Corporation (International Foundation for Telemetering, 1967-10)
      Long-loop phase-lock receivers utilize a voltage-controlled crystal oscillator (VCXO) as the first local oscillator (LO). Tuning across a band of frequencies with such an arrangement has been virtually impossible in many of the existing space and satellite tracking equipments; the characteristics of the long-loop configuration have necessitated the use of VCXO's. One particular advantage of the long-loop, the capability of maintaining coherent LO and reference frequencies for coherent demodulation of all IF outputs, is a constraint on the receiver system described here. One approach for multi-channel operation has been to employ one VCXO for each frequency; this has obvious economic limitations in applications requiring many channels. For stations used in multiple vehicle tracking, frequency-agile or frequency-hopping anti-jamming applications, or for nearly unlimited tuning capability in a data gathering station it is desirable to use a frequency synthesis technique to tune the receiver. Such a synthesizer should lend itself to on-line computer control. It is the intent of this paper to describe a technique of digital synthesizer tuning for a long-loop S-band phase-lock receiver. Hardware utilizing this technique is now in operation at Marshall Space Flight Center and Kennedy Space Center. The synthesizer provides both direct-reading pushbutton and computer tuning; frequency changing can be accomplished in microseconds. The frequency band 2200-2300 MHz is covered in 0.1 Hz steps. Although capable of providing on-line computer controlled operation, the system is presently being operated in the manual mode.
    • Central Data System Concepts for Spacecraft Data Management

      Fimmel, Richard O.; Egger, Alexander; Bello, Louis M.; Ames Research Center, NASA; TRW Systems (International Foundation for Telemetering, 1967-10)
      This paper discusses the design concepts of a central data system (CDS) for more efficient" flexible data management and its application in an advanced deep space solar probe. The design features high data sampling rates, programmable data processing, bulk data storage capability (for data sampled during periods of noncommunication), and standard experiment package/CDS interfaces. The basic system concept is based upon sampling each data point at a high rate in a fixed sequence and allowing a central processor to select, process, and format sampled data into a highly efficient format for transmission. The CDS is programmable so that data formatting and processing may be reprogrammed via the command link to optimize data transmission for unexpected conditions. Preliminary design efforts have indicated that a CDS to process data from seven particle and fields experiments can be designed, using present state-of-the-art components, to weigh 16.5 lb and consume 5.4 watts (not including bulk data storage unit) from the DC/DC converter.
    • Detection of Orthogonal Sine and Cosine Pulses by Linear Active RC-Networks

      Schmid, P. E.; 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.
    • 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.
    • 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.