• 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.
    • BIOTELEMETRY IN THE 1970’S

      Rader, D. R.; University of Southern California (International Foundation for Telemetering, 1972-10)
      A date cannot be pinpointed for the concept of using telemetry for acquiring biological data; however, it is known that the birth of biotelemetry in the form of hardware occurred about 1921--with the report of a heart sound transmitter. Biotelemetry matured only slightly from the twenties to the early fifties. During the fifties and sixties large amounts of money were administered through the money pipeline of the federal government. As a consequence, the growth during this period was bath rapid and grotesque, with tentacles reaching into scores of industrial and educational institutions. Duplication of efforts was quite common during this period and hundreds of miniature biotelemetry systems were built, but results deriving from practical application were quite limited. During the last few years, much of the chaff was shucked from this new growth, a root system developed, and biotelemetry found limited use as a tool in clinical medicine and in medical research. In the past biotelemetry has not lived up to the expectations. What about the future--will it really occupy an important place in clinical medicine and medical research? What is the economic outlook--how many jobs will it support? Which areas will require new talent? And, finally, what are the most common problems and haw can they be solved?
    • 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.
    • CHANNELIZATION AND CHANNEL MONITORING IN FDMA COMMUNICATIONS

      Gagliardi, R. M.; University of Southern California (International Foundation for Telemetering, 1972-10)
      In this paper the concept of spacecraft self-regulation of downlink power output is investigated for a hypothetical frequency division multiple access (FDMA) communication net. In this operation channels are filtered off (channelization) and monitored to determine those channels that are inactive; i.e., not transmitting. The results of the activity survey are then used to control channel gain in the spacecraft and regulate the drive power into the output amplifier. In this way, available repeater power normally not used during periods of low activity can be redistributed over the active channels to improve their performance. For maximum improvement, this requires not only adjustment of the individual channel gains, but removal of the inactive channels from the limiter. Equations are developed which are useful for system design and aid in the evaluation of resulting system performance and assessment of feasibility of implementation.
    • SATELLITE NETWORKS FOR EDUCATION

      Singh, J. P.; Morgan, R. P.; Rosenbaum, F. J.; Center for Development Technology (International Foundation for Telemetering, 1972-10)
      This paper is concerned with satellite-based educational networking. It is based on work performed in a continuing study of the potential uses of communications satellites to help meet educational needs in the United States. The paper is divided into four main sections. The first is concerned with the characteristics and structure of networks. The second section contains a discussion of pressures within the educational establishment that are providing motivation for various types of networks. This latter section also identifies studies in which networking needs for educational sectors and services are defined. Section three examines the current status of educational networking for educational radio and television, Instructional Television Fixed Services, inter- and intrastate educational communication networks, computer networks, cabletelevision for education, and continuing and proposed educational experiments using NASA’s Applications Technology Satellites. The fourth section describes possible satellite-based educational telecommunication services and three alternatives for implementing educational satellite systems. The paper concludes with some remarks concerning public policy aspects of future educational satellite system development.
    • THE USE OF MATCHED FILTERS FOR SYNCHRONIZATION

      Halpern, Peter H.; General Dynamics Corporation (International Foundation for Telemetering, 1972-10)
      Matched filters are derived for best extracting synchronization. This is done for a somewhat general class of signaling systems as well as for NRZ and SO/ PCM. The approach is based on the synthesis of finite time duration trigonometric pulses. The solution of simple calculus of variations problems yield a description of the matched filters.
    • DATA NETWORKS AND POLICY: AN INTRODUCTION

      Enslow, Philip H. Jr; U.S. Army Signal Corps (International Foundation for Telemetering, 1972-10)
      The data and computer communications services, including data networks, to be made available in the future will depend not only upon the needs and desires of the users; but also upon the economic, social, and regulatory factors that must be considered. The Office of Telecommunications Policy in the Executive Office of the President has the responsibility for recommending to the President national policies and goals in this area as well as telecommunications in general.
    • 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.
    • COMPUTER NETWORK DESIGN PRINCIPLES DERIVED FROM EXPERIENCE AND MEASUREMENTS ON THE ARPA NETWORK

      Kleinrock, Leonard; University of California (International Foundation for Telemetering, 1972-10)
      The design of the ARPA experimental computer network was a distributed effort which benefited from the talents of many people working both in concert and independently. In this paper we discuss some of the principles of design which have evolved from that effort. The measures, models and analytical results from design are further compared to simulation and measurement of the network itself; this permits us to evaluate the design tools themselves. We find that these principles are applicable to message-switching networks in general, and therefore the scope of this paper goes beyond that of the ARPA network.
    • REDUNDANT AREA CODING SYSTEM (REARCS)

      Maier, James L.; Gardenhire, Lawrence; Rome Air Development Center; Harris Intertype Corporation (International Foundation for Telemetering, 1972-10)
      Redundant area coding was proposed in an Air Force patent, James Maier inventor, to relieve the long integration time required to transmit a reconnaissance photograph through narrow-band communication circuits where upper limits of 4800 to 9600 bits/second prevail. Further development by Radiation Systems Division was funded by Rome Air Development Center’s Reconnaissance and Intelligence Division. Mr. Lawrence Gardenhire developed the analysis curves used. As redundant area coding was conceived, unimportant areas were reduced by applying different orders of resolution throughout one frame of imagery, by blanking redundant areas, or by applying encoding so one frame could consist of areas basically unchanged and areas coded to represent special land such as Forest or desert. What evolved were techniques of applying redundant reduction algorithms in both areas, producing a low/ high resolution picture. Where 3 to 1 reduction ratios were optimum for an average “busy” picture, reduction ratios exceeding 10 to I have been realized. A 9 x 9 inch, 2000 x 2000, 6-bit grey level picture that required 42 minutes to send at a 9600-bit/ second rate, or about 14 minutes for a 3 to 1 reduction, can now be sent in 5 to 6 minutes. A 10 to 1 reduction ratio makes transmitting imagery through existing ground circuits more of a reality and fulfills user requirements.
    • BANDWIDTH EFFICIENCY FOR DIGITAL COMMUNICATION VIA A HARD LIMITING CHANNEL

      Cahn, C. R.; Moore, C. R.; Magnavox Research Laboratories; North American Rockwell (International Foundation for Telemetering, 1972-10)
      The achievable burst data rate with typical channel filters is obtained for biphase, quadriphase, and eight-phase modulation. The effect of intersymbol interference in a hard-limiting channel is modeled by a time-domain representation which averages probability of error over all (truncat, ed) equally likely sequences of digits. As measured by the bit rate per unit bandwidth achieved at a given received E(b)/N(o), quadriphase outperforms biphase, but by less than a factor two, in contrast to behavior in a linear channel. Eight phase modulation appears to offer only a marginal improvement over quadriphase, and only for E(b)/N(o) > 15 db.
    • ON SYNCHRONIZATION TECHNIQUES FOR DIGITAL COMMUNICATIONS SYSTEMS

      Chang, R. W.; Bell Telephone Laboratories, Incorporated (International Foundation for Telemetering, 1972-10)
      This talk considers the transient response and the steady-state behavior of some digital phase-locked loops. When these loops are used to synchronize the transmission rate of digital communication stations, the system is capable of operating in two modes: (1) In master-to-slave mode when the communication stations are connected by digital transmission facilities, and (2) In slave-to-slave mode when these stations are connected by analog transmission facilities.
    • A SIMPLE AND EFFECTIVE HYBRID CODING/DECODING SCHEME

      Dorsch, B. G. (International Foundation for Telemetering, 1972-10)
      A simple hybrid coding/decoding scheme for the Gaussian channel is described resulting in a reasonable gain of performance compared with the corresponding single stage code, The undeteded bit error probability is estimated to be less than 10^(-5) and the probability of detected errors (deleted data) less than 1% at a signal-to-noise-ratio E(b)/N(o) of 2.3 db. The deletion rate decreases by an order of magnitude for each additional .15 db of signal energy.
    • IMAGE PROCESSING OVER THE ARPA COMPUTER NETWORK

      Pratt, W. K.; Kruger, R. P.; University of Southern California (International Foundation for Telemetering, 1972-10)
      A Communication system has been developed by the University of Southern California for providing digital image processing services over the ARPA computer network. In this system a user at a remote site may have images digitized at the USC site and transmitted over the network, or the user may supply an image for precision display. Also, image processing programs may be executed on the U.S. C. image processing system using the VICAR image processing language.
    • DATA PROCESSING FOR THE EOLE PROJECT

      Dargent, A.; Centre National d’Etudes Spatiales (International Foundation for Telemetering, 1972-10)
      The EOLE project, either known as Cooperative Application Satellite-A (CAS/A) consists of a meteorological data collection experiment. It has been lead by CNES (Centre National d’Etudes Spatiales-FRANCE) and NASA, since 1965, and the experiment has been running from last days of August 1971 through June 1972.
    • CONTRIBUTIONS TO THE DESIGN OF FUTURE ON-BOARD DATA PROCESSING SYSTEMS FOR SCIENTIFIC SPACE-CRAFT EXPERIMENTS

      Frohlich, H.; Schweizer, G.; Domier AG (International Foundation for Telemetering, 1972-10)
      Requirements for programmable dataprocessors are discussed in this paper. This is done based on the experience of the development of electronic hard-wired modules for a series of scientific space-craft experiments. The operation and the realisation of three characteristic experiments with the present technology is described. Flow diagrams are shown for cornputer control and data-processing for these experiments. From the flow diagrams some preliminary requirements for general usable programmable data processors are derived and means are shown how the requirements can be implemented.
    • RECENT DEVELOPMENT RESULTS ON THE HELIOS S-BAND COMMAND RECEIVER

      Heynisch, B.; AEG-TELEFUNKEN (International Foundation for Telemetering, 1972-10)
      By joint effort of the US and West Germany a Sunprobe will be launched by 1974 named HELIOS. In the Telecommunications Subsystem the Telecommand Receiver has a keyrole as Experiments have to be switched up to 2 AU distance from earth. The input power at the Receiver Equipment input terminal is -147 dbm with SNR of 6 db in 2 BL(o) = 32,5 Hz Loop Bandwidth. To achieve this sensitivity a Receiver in Phaselocked loop techniques with a low noise Preamplifier had to be developed. In cooperation and with consultance of well known US-Scientists it was possible to design and develope the S-Band Receiver up to the Qualifikation Model in less than two years. This report shall give a survey over concept and design of the receiver and some special experiences during development and integration tests.
    • 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.
    • A SIMPLE SECOND-ORDER DIGITAL PHASE-LOCKED LOOP

      Tegnelia, C. R.; Jet Propulsion Laboratory (International Foundation for Telemetering, 1972-10)
      A simple second-order digital phase-locked loop has been designed for the Viking Orbiter 1975 command system.** Excluding analog-to-digital conversion, implementation of the loop requires only an adder/subtracter, two registers, and a correctable counter with control logic. The loop considers only the polarity of phase error and corrects system clocks according to a filtered sequence of this polarity. The loop is insensitive to input gain variation, and therefore offers the advantage of stable performance over long life. Predictable performance is guaranteed by extreme reliability of acquisition, yet in the steady state the loop produces only a slight degradation with respect to analog loop performance. Analytical predictions and experimental performance are given in the following for both acquisition behavior and steady state phase error.
    • HOW DO YOU DEFINE BANDWIDTH?

      Scholtz, R. A. (International Foundation for Telemetering, 1972-10)
      All definitions of bandwidth have certain basic properties which make them true measures of "width". In this paper we show that different bandwidth measures are not interchangable, and note that bandwidth can be viewed as a measure of the number of dimensions added to the signal space per unit time. Methods of computing the transmitted power spectral density in a digital communication system are given and the dependence of the spectral density on the statistical structure of the information source is indicated by example. The paper closes with bandwidth comparison s for three common sets of binary telemetry signals.