• Impact of Intelligent Systems on the Telecommunication Interface

      Chien, R. T. (International Foundation for Telemetering, 1977-10)
      In the next ten years, there will be a great deal of development in the area of theory and applications of intelligent systems. Some of these systems will be related to industrial automation in manufacturing and some others will be related to automation in the cockpit of aircrafts. In this paper, a major project in computer aided decision-making (CADM) will be examined in detail. This CADM System serves as a potential co-pilot for flight operations and proposed to handle many of the routine duties of the pilot. It assists the pilot in data-processing, signal detection, flight planning, navigation, obstacle avoidance, and interaction with ground and air communicators. The purpose of this paper is to examine the new environment and the impact it has in telecommunication needs in the direction of future research and development. A movie will be shown of the project demonstrations.
    • An Integrated Error Correcting/Pseudo Random Communication System

      Schiff, Maurice L.; ITT Aerospace Optical Division (International Foundation for Telemetering, 1977-10)
      This paper describes a pseudo random (PN) communication system with an integral error correcting code. The error codes are again based on maximal length sequences and simultaneously provide coding gain with bandwidth expansion. A basic modem starting at 2400 bps data rate and expanded to a 5 Mbps chip rate is described. Theoretical and hardware test results are presented to verify the concepts. Finally, synchronization of this system is discussed. A PN range extension concept is developed which improves the acquisition time with only a trivial increase in system complexity.
    • International Telemetering Conference Proceedings, Volume 13 (1977)

      International Foundation for Telemetering, 1977-10
    • JTIDS Modular Design to Use SAW Devices

      Grasse, Charles L.; Teledyne MEC (International Foundation for Telemetering, 1977-10)
      The Joint Tactical Information Distribution System (JTIDS) concept is designed to integrate the military's needs for communication, navigation and identification equipments into a cost-effective avionic suite. A key element to be used in achieving these goals is the surface acoustic wave (SAW) bandpass filter...in the form of a bandwidth selectable module. In order to satisfy the JTIDS requirements of today, as well as the Tactical Information Exchange Systems (TIES) of the future, it is necessary to utilize state-of-the-art SAW resonator/filter designs ... in conjunction with more conventional SAW bandpass filter technology. It is this approach that will make possible the quality performance required in a small, low cost module.
    • Modeling of Optical Propagation in the Underwater Environment

      Karp, Cherman; Naval Ocean Systems Center (International Foundation for Telemetering, 1977-10)
    • MSK Modulation for Multiple Access

      Magill, E. G.; Fairchild Camera and Instrument Corporation (International Foundation for Telemetering, 1977-10)
      Minimum Shift Key (MSK) is known to possess desirable qualities, such as low spectral sidelobes and dual channels quadrature in both phase and sampling time. It is also a robust signal, tolerant to considerable amplitude limiting and spectral filtering. MSK modulation of Pseudo Noise (PN) sequences can be used to effect a communication network with multiple access, which can be of either random or assigned synchronism. Such a network exhibits resistance to jamming by external signals in the form of processing gain. This approach leads to multiple access terminal designs which are coherent, with a single RF front end which is not phase locked. A particularly effective implementation outlined in this paper utilizes a Charge Coupled Device (CCD) filter matched to the PN sequence as the basic correlating device for multiple access.
    • Multiple Access Methods in Commercial Communications Systems

      Dixon, R. C.; Spectrack Systems Inc. (International Foundation for Telemetering, 1977-10)
      Time division and/or code division multiple access techniques based on spread spectrum modulation and demodulation technology have found wide application in military systems. These techniques also offer advantages for use in systems that allow for large numbers of users in civil communications systems. This paper considers spread spectrum multiplexing as a technique that allows time division multiplexing multiple access to communications networks. It also provides for multiple networks to operate in the same band through code division multiplexing.
    • NASA Standard 4 x 10⁹ Bit Spacecraft Tape Recorder

      Welch, James P.; Odetics, Inc. (International Foundation for Telemetering, 1977-10)
      The concept of employing standard spaceborne hardware to meet the needs of present and future spaceborne missions is the beginning of a new era. In this paper, attention is focused on describing the functional characteristics of a 4 x 10⁹ bit magnetic tape recorder that will become the standard tape recorder for future satellite missions. The recorder development was directed by NASA Goddard Space Flight Center.
    • NASA Standard Communications and Data Handling Subsystem

      Robinson, Daniel L. (International Foundation for Telemetering, 1977-10)
      At the 1975 International Telemetering Conference Charles F. Trevathan discussed the Multimission Modular Spacecraft (MMS) in general and the Communications and Data Handling (C&DH) subsystem in particular. The National Aeronautics and Space Administration's Goddard Space Flight Center (NASA GSFC) Is managing the MMS program and is integrating the first spacecraft, the Solar Maximum Mission, in-house. Contracts have been let for the Modular Power Subsystem (MPS), Attitude Control Subsystem (ACS) and the Communications and Data Handling (C&DH) Subsystem. The C&DH subsystem provides the command and telemetry link between the spacecraft and the terrestrial system; distributes commands to and collects telemetry from all spacecraft systems via a duplex serial multiplex data bus and Remote Interface Units (RIU's); and contains on board computation capability. The C&DH is a single 4 x 4 x 1- 1/2 foot module. The staffed module weighs 270 pounds including 60 pounds of mission unique equipment. The future for this kind of versatile hardware is exceptionally bright as it is cost effective and its modular structure permits repair, refurbishment and even modification/dating in space.
    • NASA Teleconferencing Pilot Project (An Evaluation of Teleconferencing as a Substitute for Travel)

      Fordyce, Samuel W.; NASA (International Foundation for Telemetering, 1977-10)
      NASA conducted a Pilot Project during 1975 and 1976 to determine the extent that teleconferencing could replace travel to meetings. The network consists of approximately 34 teleconference rooms and 50 fast facsimile machines, all interconnected on private lines to a master switchboard in Huntsville, Alabama. In addition, portable conference telephones augmented the voice network, and experimental video teleconferences were tried. Evaluations show that the teleconferences "saved" travel costs approximating 21% of the travel budget at a communications cost of 3% of this budget. The unused travel funds were diverted into travel other than to management meetings, and consequently, coordination may have improved. This paper discusses the operation of the Pilot Project, which has matured into an operational teleconference network. This experience may be of value to other organizations wishing to adopt teleconferencing.
    • New Types of Flush-Mounted Telemetry Antennas

      Sindoris, Arthur R.; Jones, Howard S., Jr.; Reggia, Frank; Department of Army (International Foundation for Telemetering, 1977-10)
      Over the past few years new and unique types of cavity-backed, slot antennas have been developed that mount flush to the surface of a missile. These antennas have been designed and built to operate in the 300 MHz to 3 GHz frequency range and to produce low-gain (typically isotropic) wide-angle coverage with moderate radiation efficiency. As well as insuring good electrical performance, the basic design employs a copper-clad, dielectric-loaded cavity into which the radiating slot is machined or etched. This construction technique provides four important advantages: (1) The almost arbitrary shape or form factor of the cavity allows flush mounting to the surface of the missile or sandwiching between internal components with only the radiating slot exposed to the exterior of the missile. (2) Fabrication is simple. (3) Cost is low. (4) Mechanical strength is high. The cavity backing the slot is filled with a moderately high, dielectric constant material (such as a silicone, Teflon, or epoxy fiberglass) with a relative permittivity in the 2.5 to 4.5 range to decrease the size of the cavity and to provide mechanical strength to the antenna. The RF connection to the cavity is made by an inductive post and a coaxial connector. A 50 ohm input impedance is obtained over frequency bandwidths of 3 to 10 percent. By connecting two or more of these slot antennas together in a prescribed phase and amplitude relation, the direction of the radiation pattern can be controlled. Sidelooking or forward-looking patterns are possible by simple changes in feed network cable connections. The easy tunability of one of these new types of antennas allows application over greater than a 2:1 frequency range without any change in antenna dimensions.
    • Omnidirectional Telemetry Antennas

      Munson, Robert E.; Ball Brothers Research Corporation (International Foundation for Telemetering, 1977-10)
      Missiles, rockets, and satellites need as much uniform gain as possible to provide continuous telemetry coverage. The theoretical limit of an ideal antenna would be 0 dB gain with 100 percent coverage of 4π steradians. It is not practical to attain the theoretical limit in practice on missiles, rockets, and satellites. This paper describes how closely the theoretical limit can be approached.
    • A Practical Look At Antenna And Propagation Requirements in Biotelemetry Systems For Fresh Water Fish

      Lindsay, J. E.; Long, F. M.; Weeks, R. W.; University of Wyoming (International Foundation for Telemetering, 1977-10)
      Propagation from a transmitter/antenna implanted in a fresh water fish is discussed. The choice of operating frequency based upon fish size, antenna efficiency and refraction effects is presented. The implanted linear antenna is placed laterally along the fish. It is shown that for parallel polarization (E in the plane of incidence) the wave, in air, has polarization dependent upon the elevation angle of the receiving antenna. For perpendicular polarization the polarization of the wave is always horizontal. Hence the polarization of the signal in the air depends upon the fishes position in the water. This leads to the conclusion that ground based receiving antennas should be circularly polarized so that either case can be handled. For air-borne tracking, the major cone of reception places the aircraft at higher elevation angles and hence requires a horizontally polarized antenna. Since the fish can be at various azimuthal angles, a circularly polarized antenna placed beneath the aircraft is dictated. The paper concludes with a discussion of an actual operating system as used by the U.S. Fish and Wildlife Service on the Truckee River.
    • Processing Radiation Data on Board TIROS-N Satellite

      Wisniewski, J. H.; Ford Aerospace & Communications Corp. (International Foundation for Telemetering, 1977-10)
      The function of the data processing unit (DPU) as part of a space environment monitor subsystem is described, with emphasis on special features in the data handling process. Important design goals for achieving DPU performance are outlined. Design implementation to achieve these goals is discussed. Some of the more complex circuits are described in detail as examples of onboard data processing. The packaging approach for effecting savings in weight and power is also presented.
    • Pseudo-Random Code Sidelobe Canceller

      Haber, Conrad H.; Nossen, Edward J.; Government Communications Systems RCA (International Foundation for Telemetering, 1977-10)
      During acquisition of direct sequence pseudo-noise signals, time sidelobes are produced at the correlator output which will degrade detection performance. These sidelobes may be the result of additive noise, channel distortions, deliberate jamming or the non-ideal correlation function of truncated code sequences. In order to minimize these sidelobes, special codes can be selected based on their low sidelobe levels, or some special sidelobe reduction or cancellation algorithm may be devised. A sidelobe cancellation algorithm for use with LSI correlators has been simulated. Segments of a maximum length code word as well as a totally random bit stream were tested. The simulation results show that the largest sidelobes are reduced by a small amount; however, the majority of the sidelobes are reduced by as much as 6 dB. Consequently the false alarm rate for a particular threshold setting may be reduced. A compatible technique for the derivation of a CFAR reference from the same correlator was also successfully simulated.
    • Quadrature Modulation Hybrid Voice and Data Modem

      Lerner, Theodore; Lerner Technology Inc. (International Foundation for Telemetering, 1977-10)
      The Quadrature Modulation Hybrid Modem is a new system designed to provide voice only, data only, or combined voice and data communication. It provides good voice intelligibility at low values of C/N0 by making use of a quadrature modulation technique which permits essentially nonthresholding demodulation of the voice signal. Power sharing between voice and data signals can be easily changed to accommodate different requirements. Intelligibility tests have been performed and indicate an intelligibility of 90% in the voice-only modem at a value of C/N₀ of 43 dB-Hz, and an intelligibility of 80% in the combined voice and data mode at a value of C/N₀ of 43 dB-Hz with an error rate for data of 10⁻⁵.
    • Results of a Q-M/PSK Data Modem Performing in a Hybrid, Voice and Data Mode, Through the ATS-6 Satellite

      Golab, Joseph; Duncombe, Christopher; Bland, Robert G.; U. S. Department of Transportation (International Foundation for Telemetering, 1977-10)
      The Transportation Systems Center (TSC), under the sponsorship of the FAA, has been involved in the development of advanced voice/data multiplexed modems applicable to ground-aircraft communications via satellite in support of the AEROSAT program. TSC was assisted by the Canadian Ministry of Transport (MOT), Communications Research Center (CRC), in the planning and conducting of recent flight test experiments using the NASA ATS-6 satellite.
    • Review of Microstrip Antenna Development at the Pacific Missile Test Center

      Kaloi, C.; Pacific Missile Test Center (International Foundation for Telemetering, 1977-10)
      Pacific Missile Test Center personnel have been conducting theoretical and experimental studies on microstrip antennas since 1965. A number of operational microstrip antenna systems have been developed. This report reviews development efforts at Pacific Missile Test Center on types of microstrip antenna elements used in these operational systems. Results of near field probing of different microstrip antenna elements are presented. These results are used as a basis to discuss microstrip antenna electrical characteristics such as orthogonal current oscillation, orthogonal charge oscillation, dipole moment of charge distribution oscillation, dipole moment of charge distribution rotation, far field radiation patterns, polarization, etc. Application of microstrip arraying techniques on thin flexible substrates that can be readily mounted conformally to the exterior surface of a missile without missile disassembly is discussed.
    • A Satellite Automatic Control System

      Bleiweis, J. J.; Redman, P. C.; COMSAT Laboratories (International Foundation for Telemetering, 1977-10)
      The primary task of existing satellite control centers is to automatically monitor the operational performance of existing satellites and to manually generate control commands so that these satellites remain within specified operational limits. This paper describes some basic characteristics of an existing satellite control center and identifies a method that may be employed to gradually introduce automatic commanding to the facility. Candidate methods of automatic commanding are described.
    • Self-Steering Arrays

      Kummer, W. H.; Hughes Aircraft Company (International Foundation for Telemetering, 1977-10)
      Self-steering arrays using complete receiver-transmitter-signal processing systems to direct the beam of an antenna automatically have been developed. These systems offer an alternative to mechanically gimballed systems for satellite communication applications. The operation of such systems using either a pilot signal or a phased lock loop technique for self-steering is described. Also described is an engineering model built for satellite-to-earth communications which incorporates these techniques. Additionally, other systems now in breadboard configurations are mentioned briefly. A summary of power requirements for a projected 25-module system has been included to indicate the feasibility of larger systems. Test results for the engineering model have proved satisfactory, and show that these systems can definitely be valuable in applications similar to the tracking and data relay satellite system (TDRSS) described here.