• 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.
    • 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.
    • Underwater Optical Beam Tracking

      Gagliardi, R. M.; University of Southern California (International Foundation for Telemetering, 1977-10)
      The use of blue-green laser frequencies for establishing an air ocean underwater communication channel has been well accepted. However any attempt to initialize or maintain such a link will invariably require some method of accurately spatially pointing and tracking the penetrating beam. In this paper we present results of a study concerned with determining the ability to spatially track an optical after undergoing underwater propagation. By invoking the concept of modulation transfer theory and substituting established propagation models for underwater coherence functions, the focal plane intensity patterns generated in wide angle optical lensing systems can be determined, as a function of the link characteristics (e.g. sea state, depth into the ocean, turbulence, etc.).With the intensity pattern modeled, the behavior of various forms of optical trackers can be analyzed by the application of standard tracking loop theory. Of particular interest here is the application of well known mathematical tools, such as Kolmogorov theory, which allows generalized statistical analysis to be performed on both linear and nonlinear dynamical systems. The result of such an approach is the development of a differential equation whose solution yields the statistics of the tracking error. Theoretical studies of this type have been examined previously for generalized scattered optical fields [1]. With these basic approaches as a guide, mean squared tracking errors can be derived, which assesses the perfomance of the beam tracker in relation to the channel characteristics.
    • Adaptive Array Control Concepts for TDRSS

      DuPree, J. E.; TRW Systems (International Foundation for Telemetering, 1977-10)
      The Tracking and Data Relay Satellite System (TDRSS) will use an Adaptive Ground Instrumented Phased Array(AGIPA) system for remote beamforming and tracking of low-orbit user spacecraft. This paper introduces the control concepts involved in its beamforming, tracking, and calibration. These concepts are related to the Kalman filter. Several suboptimal, but attractive, tradeoff options are discussed.
    • Fiber Optical System Performance with Avalanche Gain Detection

      Sorensen, Alfred N.; California State University (International Foundation for Telemetering, 1977-10)
      The purpose of this paper is to consider optical system performance for selected digital signal formats when shot noise limited avalanche photodetection is implemented. Performance characteristics for binary on-off keyed (OOK) and pulse position modulation (PPM) are given, in addition to M-ary PPM and PAM.
    • 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.
    • VHF Adaptive Array Test Results

      Zeger, Andrew E.; Burgess, Lawrence R.; General Atronics Corp. (International Foundation for Telemetering, 1977-10)
      A four-element Anti-Jam Antenna Array (AJAA) system has been built to provide protection for U.S. Marine Corps inter-command post communications in the 30-76 MHz band. A unique and important feature of the AJAA system is its ability to spatially null jammers down to a level below that of the desired signal. This capability and the prevention of accidental cancellation of the desired signal is achieved by using the desired signal's direction-of-arrival (DOA) in a prebeamformer located ahead of the adaptive beamformer. A positive S/J at the array output is required to prevent capture by a co-channel interference in standard FM field radios. Antenna range tests were performed on the AJAA system using AN/PRC-77 radios as far-field signal and jamming sources. Results of these tests show that the AJAA provides an intelligible FM voice signal at its output while simultaneously suppressing three jammers.
    • Comparison of Analog and Digital Transmissions for Multichannel Voice

      Birch, J. Neil; Office of the Secretary of Defense (International Foundation for Telemetering, 1977-10)
    • Approximate Design Formulae and Procedures for Designing Hybrid Telemetry Systems Using an FM Carrier

      Lantz, Norman F.; Nichols, Myron H.; The Aerospace Corporation (International Foundation for Telemetering, 1977-10)
      Approximate engineering design formulae are presented. These are based on Rice's model of pop plus fluctuation noise in FM receivers. Several design examples are given. One hybrid system contains a baseband acoustic signal plus a PCM/FM subcarrier and another system contains a baseband PCM signal plus two PCM/FM subcarriers. Depending on carrier modulation parameters, the design formulae show that either pop noise or fluctuation noise in the carrier discriminator output may predominate in determining the bit error probability in the baseband and/or subcarrier services. Examples of each are given. The hybrid systems mentioned above were simulated in the laboratory. Test results are presented and show satisfactory agreement with the design formulae.
    • Best Source Selector System

      Alday, J. R.; Fleet Analysis Center (International Foundation for Telemetering, 1977-10)
      This system was developed in order to fulfill a need existing at the Fleet Analysis Center (FLTAC) Field Station-Caribbean, Telemetry Site at Roosevelt Roads, Puerto Rico. At the Field Station there exists four 16-foot diameter, two 8-foot diameter missile telemetry tracking systems plus a four frequency downlink Airborne Data Link (ADL) aircraft. With associated receivers, total number of video sources can be on the order of forty. Although all sources are recorded on magnetic tape and can be played back, only one or two sources can be displayed on high speed oscillographs simultaneously in "real time." The Best Source Selector System (BSSS) was developed in order to display, in real time, a continuous composite missile telemetry record which may consist of several individual sources. This System has been used continuously for the past three years for all missile telemetry operations at the Atlantic Fleet Weapons Training Facility (AFWTF), Puerto Rico. It has saved many man-hours of labor, searching tapes for bits and pieces of data and consequently, preliminary flight analysis and reporting to firing units (QUICKREPS) have been speeded up many fold.
    • Telemetry Antennas for Deep Space Probes

      Brejcha, Albert G.; Smith, Charles A.; Jet Propulsion Laboratory (International Foundation for Telemetering, 1977-10)
      The requirement for real time imaging telemetry and the continued increase in science payloads on deep space missions have played a major role in the evolution of deep space probe telemetry antennas. This paper describes the high data rate telemetry antennas that were flown on the Mariner Mars 1969 and 1971, the Mariner Venus Mercury 1973, the Viking 1975 and the Voyager spacecrafts. Performance parameters are reviewed and general design concepts are described. The Mariner Mars 1969 and 1971 antennas were single frequency (S-band), one meter diameter antennas. The Mariner Venus Mercury 1973, Viking 1975 and Voyager antennas were dual frequency (S and X-band), with diameters of 1.4 meters, 1.5 meters and 3.7 meters respectively.
    • 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.
    • 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.
    • Detection of Scattered Optical Fields with Focal Plane Ring Detectors

      Vilnrotter, Victor A.; Hughes Aircraft Company (International Foundation for Telemetering, 1977-10)
      It is demonstrated that when communicating through scattering channels order-ofmagnitude improvement in system performance is possible by employing focal-plane processing techniques to recover some of the scattered radiation. Maximum a-posteriori and suboptimal system structures are derived and their performance evaluated. System sensitivity to the errors in the optimal weighting functions is discussed.
    • A Frequency Modulated S-Band Telemetry Transmitter

      Homa, M. L.; Ward, J. H., Jr.; E-Systems (International Foundation for Telemetering, 1977-10)
      The need to efficiently collect data from remote locations has resulted in the widespread use of radio frequency telemetry. This paper addresses the requirements, considerations, and implementation of such a system. Since many components of a telemetry link are subjected to harsh operating environments, considerations of system constraints imposed on the transmitter by these conditions will be presented. Several design approaches of an S-Band frequency modulated telemetry transmitter will be offered, and tradeoffs associated with each discussed. Having selected the most desirable transmitter design approach a pictorial display of the hardware used to fulfill the requirements will be presented along with measured performance data. The key circuits discussed will be an S-Band VCO, parametric divider, buffer/power amplifier, and stabilizer/modulator. The RF circuits employ microwave integrated circuit construction while the stabilizer/modulator utilizes thin and thick film hybrid technology. Extensive use was made of computer analysis resulting in uniformly producible circuits that provide good correlation between measured and specified performance. This helped to produce a 25% reduction in production cost over the previous discrete component design of 1969 vintage. Basic circuit design lends itself well to special mechanical configurations, as well as flexibility in modulation formats and RF power output levels. By using the computer aided design approach, five percent RF bandwidths were realized which would enable the transmitter to be frequency agile for secure or multivehicle telemetry.
    • Encoding of Telemetry Data in a Standard Video Channel

      Rieger, James L.; Naval Weapons Center (International Foundation for Telemetering, 1977-10)
      Various methods for compressing of a television image to fit a channel of reduced bandwidth are available; most are difficult and/or expensive to use, and many degrade the resulting picture appreciably. This paper describes an alternative method of placing the signals which accompany the picture within the passband of a picture, and separating them again at the receiving end with minimum crosstalk and picture degradation.
    • A Data Acquisition System Featuring On-Board Processing

      Endsley, Neil H.; Lee, Kyong H.; Maschhoff, Robert H.; Gulton Industries Inc./DSD (International Foundation for Telemetering, 1977-10)
      A data acquisition system for the telemetry data on the Technology Development Vehicle (TDV) program is presented. To meet the major experimental objectives of the TDV mission - the collection of high frequency vibration and acoustic data on a re-entry vehicle - required some unusual design approaches. It is shown that collection of this data requires a great deal of data compression. This was accomplished using a technique of on-board data processing - actually performing the first step of data reduction in flight. The entire data acquisition system is described in light of the requirements imposed by the data with emphasis on unusual problems and solutions. Results of ground tests in an anechoic chamber are presented, and a brief discussion of the errors involved in onboard processing is given.
    • ACMR/I System

      Parker, J.; Cubic Corp. (International Foundation for Telemetering, 1977-10)
      The instrumentation system described provides real-time attitude and position data on 8 high-dynamic fighter aircraft and position data on 12 additional cooperative targets. Position data is derived from multilateration range measurements using FM-CW phasecomparison techniques. Attitude and acceleration data is obtained from a strap-down inertial system initialized by the ranging system. Digital data is transmitted to and from the target by frequency shift keying of the ranging carrier. A multiprocessor ground computer using Kalman filter techniques provides a total state vector for each participant at a rate of 10 per second. The multiprocessor also provides real-time missile simulation for performance scoring. The Display and Debriefing Subsystem provides real-time computer-drawn pseudo three-dimensional display of the aircraft, total replay capability, and control of the entire system from the operator's console.
    • Application of the Global Positioning System (GPS) to Space Shuttle Navigation

      Nilsen, Peter W.; Axiomatic (International Foundation for Telemetering, 1977-10)
      The present baseline Space Shuttle navigation system is comprised of several separate subsystems: TDRSS doppler ranging, TACAN (Tactical Air Navigation), MSBLS (Microwave Scanning Beam Landing System), and ground tracking. With the advent of the DOD development of the GPS, it may be possible to replace several of these subsystems with an on-board GPS navigation system. However, the Shuttle signal dynamics and environmental considerations impose unique and severe requirements for a GPS navigation system. Consequently, a preliminary study has been conducted to define requirements and configure candidate GPS systems for the Shuttle navigation function. Three configurations have been considered: an early test/demonstration system, which could be flown on early OFTs (Orbital Flight Tests), an interim system having greater capability but still not having full operational capability, and, finally, a fully operational system. A description of the test/demonstration and interim systems and the results of performance analyses are given. These preliminary results indicate that a GPS navigation accuracy greater than that obtained from the baseline system can be obtained for the orbital and de-orbit phases of the Shuttle mission.
    • The Application of the NAVSTAR Global Positioning System to the Evaluation of the Next Generation Long Range Ballistic Missiles

      Moses, Jack; Magnavox Government and Industrial Electronics Co. (International Foundation for Telemetering, 1977-10)
      The NAVSTAR Global Positioning System (GPS) is a joint services program currently undergoing concept validation. The program is managed by the Air Force with participation by the Navy, Army, Marines, and Defense Mapping Agency. When fully deployed, GPS will provide highly precise position and velocity to a variety of users. The Magnavox Advanced Products Division, under several funded contract activities, is participating in the development of several user equipments and studying the application to many others. This paper discusses the results of a study performed for the Space and Missile Test and Evaluation Center (SAMTEC) Vandenberg AFB to determine the feasibility and capability of the use of the NAVSTAR Global Positioning System as a tracking instrument and guidance evaluation system for the next generation ballistic missiles. The paper examines three primary approaches to the missile tracking problem using GPS. Recommendations for missile instrumentation are provided based upon studies in areas such as mission scenario, environmental factors, systems requirements and constraints, and configuration analysis.