• POLICY ISSUES IN CABLE COMMUNICATIONS

      Hinchman, Walter R.; Office of Telecommunications Policy (International Foundation for Telemetering, 1972-10)
      Cable communications constitutes a complex and dynamic new medium for both selective and mass distribution of entertainment and information programming, as well as new information exchange services. The complexity of technical, operational, social, political, and economic issues relating to cable probably exceeds that of any electronic communications development to date. Fortunately, there are relevant experiences from many other communications operations -- common carriers, broadcasters, the publishing industry, etc. -- which provide insights into the probable evolution of cable communications and into the many policy issues which exist or will arise. By carefully selecting from among several options for industry structure and integration, it should be possible to achieve -with minimal detailed regulation -- a cable communications industry which encourages diversity of information and entertainment services, guarantees access by all responsible interests, avoids excesses of monopoly powers, and is truly responsive to public needs and interests. That, at least, is the objective of the Administration’s current Cabinet-level policy review.
    • SPECIAL SERVICES TO NEIGHBORHOOD AND HOME: A COMMUNITY TELECOMMUNICATION DEMONSTRATION CONCEPT

      Hiibner, Calvin W.; Siegel, Alan R.; Department of Housing and Urban Development (International Foundation for Telemetering, 1972-10)
      This paper discusses the potential impact of cable television or broadband communications on the urban environment. It suggests that the availability of improved two-way communications between individuals and public institutions presents new opportunities for delivering social services in a cost effective manner. Also, that this mode of delivery may be superior in other ways to our present system of delivery. Unanswered questions do remain on the use of technology for this purpose, however, and to answer these questions an experimental demonstration in one or more “real” cities is suggested so that future urban telecommunications systems can be designed with social service delivery in mind.
    • AIRBORNE VISIBLE LASER OPTICAL COMMUNICATION EXPERIMENT

      Randall, J. L.; Marshall Space Flight Center (International Foundation for Telemetering, 1972-10)
      A series of optical communication experiments between a high altitude aircraft at 18.3 km (60,000 ft) and a ground station are planned by NASA in the summer of 1972. The basic concept is that an optical tracker and transmitter will be located in each terminal. The aircraft transceiver consists of a 5-mW HeNe laser transmitter with a 30-megabit (Mbit) modulator. The ground station beacon is an argon laser operating at 488 mn. A separate pulsed laser radar is used for initial acquisition. The objective of the experiment is to obtain engineering data on the precision tracking and communication system performance at both terminals. Atmospheric effects on the system performance are of prime importance.
    • USE OF IMPLANTED TELEMETRY IN VASCULAR RESEARCH

      Rader, R. D.; Stevens, C. M.; Henry, J. P.; Meehan, J. P.; University of Southern California (International Foundation for Telemetering, 1972-10)
      This paper outlines a program to study the development and progression of essential hypertension in dogs through the use of totally implanted telemetry. In light of the role that social interaction may play in the development of hypertension in man, emphasis is placed on inducing and monitoring the effects of social strain in the dog: and because of the role the kidney may play in the development of hypertension, a model for renal flow has been developed. The effect that pharmacological concentrations of vasodilator and vasoconstrictor agents have on renal hemodynamics are evaluated. Preliminary data from investigations on the renal hemodynamics of unrestrained dogs in various stages of psychophysiological stress are presented.
    • IMPLANTABLE ULTRASONIC BLOOD FLOWMETERS

      Meindl, J. D.; Stanford University (International Foundation for Telemetering, 1972-10)
      Accurate measurement of pulsatile blood flow can be achieved on a chronic basis in research animals through the use of totally implantable ultrasonic flowmeters. The continuous wave Doppler flowmeter provides an attractive technique for measurement of flow velocity at a particular location such as the center of the lumen; the pulsed Doppler flowmeter is attractive for measurement of flow velocity distribution or profile across the vessel and lumen diameter, and hence volume flow. Both instruments can be electronically precalibrated and exhibit no baseline or scale factor changes during chronic experiments. Custom designed silicon monolithic integrated circuits offer significant advantages in reduced size and power drain as well as improved reliability in these instruments.
    • DIGITALLY IMPLEMENTED CLOCK ACQUISITION LOOPS FOR LOW SNR DATA SIGNALS

      Schoolcraft, R. W.; Magnavox Research Laboratories (International Foundation for Telemetering, 1972-10)
      The development of powerful error correction codes for binary data channels has generated a requirement for high performance clock acquisition loops. These loops must provide clean estimates of the data clock at very low data SNR in order to prevent dissipation of the coding gain through noise in the data recovery timing. The key element in high performance clock loops is the method of extracting clock information from the received data stream. Three loops are described which illustrate several extraction concepts and which can be used as design guides. The first loop extracts clock information by use of the function D(t)•D(t+ T/2). The extractor is implemented almost entirely with digital logic elements and is very compact. The third loop is extremely efficient due to the use of a time window which is open for only a short time around the transitions of the data. Its implementation is heavily analog. The second loop is a hybrid of the first and the third falls between them in both performance and complexity. Performance curves are presented for the three loops in terms of data SNR degradation as a function of data SNR and loop bandwidth. Experimental data is presented for the first loop.
    • IMPROVEMENTS IN DEEP-SPACE TRACKING BY USE OF THIRD-ORDER LOOPS

      Tausworthe, R. C.; Crow, R. S.; Jet Propulsion Laboratory (International Foundation for Telemetering, 1972-10)
      Third-order phase-locked receivers have not yet found wide application in deep-space communications systems because the second-order systems now used have performed adequately on past spacecraft missions. However, a survey of the doppler profiles for future missions shows that an unaided second-order loop may be unable to perform within reasonable error bounds. This article discusses the characteristics of a simple third-order extension to present second-order systems that not only extends doppler -tracking capability, but widens the pull-in range and decreases pull-in time as well.
    • DATA QUALITY ASSURANCE IN A SHIPBOARD COMPUTERCONTROLLED TELEMETRY SYSTEM

      Baggot, H. E.; Interstate Electronics Corporation (International Foundation for Telemetering, 1972-10)
      This paper describes a computer-controlled telemetry system used as a shipboard telemetry station for U. S. Navy Poseidon FBM weapon system testing. Built into the equipment are rather sophisticated automatic tests. These tests allow expected. equipment performance to be verified under conditions very nearly like those to be encountered during the data receiving mission. Also built into the equipment are provisions for real-time display and quick-look playback capability. These provisions allow evaluation and analysis of the test results within a few hours of the operation.
    • ON-BOARD REGISTRATION AND REDUNDANCY REDUCTION METHOD FOR QUASISTATIONARY POISSON PROCESSES

      Khodarev, J.; Nikolayev, V.; Skobkin, I.; Shtarkov, J.; Vassiliev, E. (International Foundation for Telemetering, 1972-10)
      Many processes in space are related to Poisson flows of particles. Usually, the aim of experiment is to study the intensity of such a flow. Each of the samples obtained in the course of measurement represents the number of particles detected during a sampling period and sample values are related with the flow intensity only statistically. So the less the sample value is, the greater the r.m.s. error in estimating the flow intensity. With any fixed "accumulation time" values of some samples are too small to provide required accuracy. Hence, these are redundant from the view-point of telemetering them to the Earth. A simple method is suggested for reducting this redundancy which assures a preset r.m.s. accuracy of measurement. The main feature of the method is that the accumulation lasts until the number of registrated particles reaches a preset level. In this case the "accumulation time" is variable and thus data compression is completely accomplished by appropriately organized aquisition.
    • HYBRID AND CONCATENATED CODING APPLICATIONS

      Hofman, L. B.; Odenwalder, J. P.; NASA; LINKABIT Corporation (International Foundation for Telemetering, 1972-10)
      This paper presents some of the results of a study to evaluate the performance and implementation complexity of a concatenated and a hybrid coding system for moderate speed deep space applications. It is shown that with a total complexity of less than three times that of the basic Viterbi decoder, concatenated coding improves a constraint length 8 rate 1/3 Viterbi decoding system by 1.1 and 2.6 dB at bit error probabilities of 10^-4 and 10^-8, respectively. With a somewhat greater total complexity, the hybrid coding system is shown to obtain a 0.9 dB computational performance improvement over the basic rate 1/3 sequential decoding system. Although substantial, these complexities are much less than those required to achieve the same performances with more complex Viterbi or sequential decoder systems.
    • RECONSTRUCTION OF ANALOG SIGNALS AND CHOICE OF SAMPLING RATES IN TELEMETRY

      Evdokimov, V. P.; Kolesnikov, L. I. (International Foundation for Telemetering, 1972-10)
      The reconstruction of the form of analog signals by samples by means of linear filtration is considered. Precision criterion - mean square reconstruction error and the maximum reconstruction error probability. Linear filters (reconstructing functions) of increasing difficulty are considered together with an optimal filter. A signal model is introduced by means of large set of correlation functions. The calculations of reconstruction errors are carried out for different reconstructing functions. The tables and the figures allow to determine reconstruction errors, to estimate the necessity of decreasing complexity of the filter and to choose the type of filter. The results of calculations and the recommendations of choosing the sampling rates of the sensors are made in the paper can be used by the experimenters and specialists in telemetry.
    • COMPARING BANDWIDTH REQUIREMENTS FOR DIGITAL BASEBAND SIGNALS

      Houts, R. C.; Green, T. A.; University of Alabama (International Foundation for Telemetering, 1972-10)
      This paper describes the relative, bandwidth requirements of the common digital baseband signaling techniques used for data transmission. Bandwidth considerations include the percentage of total power in a properly encoded PN sequence passed at bandwidths of 0.5, 1, 2 and 3 times the reciprocal of the bit interval, T(b). The signals considered in this study are limited to the binary class, i.e., each decision at the receiver yields one bit of information, in contrast to signaling schemes which encode groups of bits into a given signal amplitude, phase shift, etc. The study compares such signaling techniques as delay modulation (DM), bipolar (BP), biternary (BT), duobinary (DB), pair selected ternary (PST), and time polarity control (TPC) in addition to the conventional NRZ, RZ and BIΦ schemes. It is shown that several of the signals can be transmitted over channels which block frequencies below 10% of the bit rate and still lose less than 5% of the total signal power. Based upon the dual consideration of a large number of regularily-spaced level transitions to assure synchronization plus a minimum of bandwidth and no dc response, it is concluded that DM and PST are the best choices.
    • A NEW TYPE OF PSK ANTI-AMBIGUITY SYSTEM FOR SATELLITE APPLICATIONS

      Pera, L.; European Space Technology Centre (ESTEC) (International Foundation for Telemetering, 1972-10)
      In coherent PCM-PSK links the problem of solving the phase ambiguity in the reconstruction of the subcarrier has been traditionally solved by making use of the knowledge of some part of the transmitted message or by employing MARK-type codes. After a brief discussion of these well-known methods a new approach is proposed which makes use of an auxiliary non-ambiguous PSK demodulator based on the estimation of the sign of the message transitions. It is shown that no particular requirements on the noise performance of this auxiliary demodulator is needed to ensure acceptable overall performance of the antiambiguity system. A particularly simple hardware implementation is indicated and experimental results are presented for cases of practical interest.
    • APPLICATION OF RANGE COMMANDERS COUNCIL DOCUMENT 118-71 TEST METHODS TO RANGE MANAGEMENT-SAMTEC

      Radom, Stanley R.; Vandenberg Air Force Base (International Foundation for Telemetering, 1972-10)
      Range management techniques utilized by the SAMTEC enable telemetry system and subsystems to be validated for operational support readiness. Application of test methods from Range Commanders council Document 118-71 are described for solar calibration of the telemetry receiving system, PCM bit error rate and FM noise power ratio testing. Limitations of noise power ratio testing is described including need for additional range user performance requirements. The use of test results provides SAMTEC range management with a near realtime certification of telemetry system performance accuracies. System performance levels are established which provide a “red flag” indicator to alert range management that systems are below the norms expected. Application of the test methods and the use of the red flag provides the SAMTEC range management the decision making information required to employ minimal telemetry systems and manpower resources in the effective achievement of range user program support requirements. These test methods will be used to establish the data base for scoring the range technical support contractors performance incentive fee. An additional benefit of the test methods is their application for the test and acceptance of new telemetry systems and subsystem.
    • A MOBILE TONE RANGE/RDF SYSTEM FOR TELEMETRY TRACKING OF SOUNDING ROCKETS

      Mayer, G. K.; Deutsche Forschungs-und Versuchsanstalt for Luftund Raumfahrt (International Foundation for Telemetering, 1972-10)
      A simple and versatile tracking system is described, providing trajectory information for any rocket, balloon or airborne scientific device which employs telemetry. The system is thought to serve as a back-up or a replacement for radar to provide the trajectory data of sounding rockets. Two basic systems are comprised: the tone range system, providing the slant range information and the RDF system, providing angular data. Data reduction is handled by a small Computer.
    • CONCATENATED CODING FOR LOW DATE RATE SPACE COMMUNICATIONS

      Chen, C. H.; Southeastern Massachusetts University (International Foundation for Telemetering, 1972-10)
      In deep space communications with distant planets, the data rate as well as the operating signal-to-noise ratio may be very low. To maintain the error rate also at a very low level, it is necessary to use a sophisticated coding system (longer code) without excessive decoding complexity. The concatenated coding has been shown to meet such requirements in that the error rate decreases exponentially with the overall length of the code while the decoder complexity increases only algebraically. Three methods of concatenating an inner code with an outer code are considered. Performance comparison of the three concatenated codes is made. It is shown that the concatenated code with inner code a convolutional code and outer code a Reed-Solomon code performs the best among the three.
    • A NEW FM SYSTEM WITH A NOVEL MODULATOR DESIGN YIELDING HIGH LINEARITY AND THERMAL STABILITY

      Dy, B. G.; 3M Mincom Instrumentation Group (International Foundation for Telemetering, 1972-10)
      Using two integrators operating in parallel, a high linearity FM modulator was designed. When one integrator is integrating, the other is being reset; thus, each integrator is only working at half the input signal frequency. In addition, feed forward voltage is applied to compensate for constant delay in the integrator and greatly increases the linearity at high frequency. A complete MODEM system of 1 megahertz bandwidth with a system linearity of ±0.5% and a thermal stability of ±0.08%/°C was achieved.
    • CHARACTERISTICS OF PHASE DETECTORS IN PRESENCE OF NOISE

      Pouzet, A. H. (International Foundation for Telemetering, 1972-10)
      The phase detector is an important device used extensively in phase locked loops and in coherent detectors. Its characteristics must be known to predict the behaviour of the phase locked loop especially by non linear analysis. Noiseless analysis has been made for great varieties of phase detectors, but a satisfactory analysis in presence of noise is still needed. Many authors make the implicite assumption that the characteristics in presence of noise and without noise are alike, what is wrong. In fact it will be shown that all phase detector characteristics become sinusoidal at low signal to noise ratios whatever their noiseless characteristic may be. Besides, it will also be shown that when used as coherent detectors, sinusoidal phase detectors are better than linear phase detectors regarding the output signal to noise ratio, and output signal to noise spectral density ratio.
    • DYNAMIC REQUIREMENTS FOR DIVERSITY COMBINERS

      Streich, R. G.; Little, D. E.; Pickett, R. B.; ITT-Federal Electric Corporation (International Foundation for Telemetering, 1972-10)
      In order to provide nearly continuous data on missile and Space launches, polarization diversity is utilized at acquisition sites. Diversity signals are also combined to further reduce data dropouts. It is shown in this report that the right hand circular (RHC) and left hand circular (LHC) signals undergo rapid transients during certain portions of the flight, and that the channel dropouts are sometimes independent. The nature of the transients is described and a test set which simulates the transients discussed. Finally bench test data is compared with flight test data to verify that combiners with rapid transient response are required to cope with the RF transients.
    • A REAL TIME MULTIPROGRAMMED TELEMETRY SYSTEM

      Muse, G. B. (International Foundation for Telemetering, 1972-10)
      A study of several Telemetry Data Reduction Systems has revealed some common problems which reduce the effectiveness of these systems. The problems include: The high cost of real-time computer analysis programs, lengthy turnaround for data product modification, lack of testing flexibility, and reduced hardware system utilization. A computer system, 11TELFILE11, has been implemented to improve upon these problem areas. This system is operational at the Space and Missile Test Center (SAMTEC), Vandenberg Air Force Base, for support of the Minuteman III Weapons Systems.