• Method for Calculating the Pre-Emphasis Schedule for an FM/FM Telemetry System Based on Optimum Performance

      Rosen, Charles; Microcom Corporation (International Foundation for Telemetering, 1974-10)
      This paper will describe a system for calculating the pre-emphasis schedule and the required receiver IF bandwidth for FM/FM Telemetry Systems (Frequency Division Multiplexing. An investigation of the procedures presently in use, disclose that system engineers calculate their system pre-emphasis based on the 3/2 Power Law, for proportional bandwidth systems and a 6 db per octave taper for constant bandwidth systems. Systems using both proportional and constant bandwidth channels are usually left to empirical methods. The total deviation and the receiver bandwidth is assumed using empirical values previously found successful. So far, an investigation has not shown any exact technical basis for the selection of the total deviation or the receiver bandwidth to be utilized in a system.
    • A Markov Model for NASA's Ground Communications Facility

      Adeyemi, Oduoye (International Foundation for Telemetering, 1974-10)
      For those burst noise channels that can be mode l led by finite state Markov chains (FSMC) this paper presents a 'natural' way of constructing such models and in particular gives a five-state Markov chain as a model of errors occurring on the NASA's Ground Communications Facility (GCF). A Maximum Likelihood procedure applicable to any FSMC is developed for estimating all the model parameters starting from the data of error runs. Then we give a few of the statistics important for estimating the performance of error control strategies on the channel.
    • Deep Space Telecommunications-Pioneer Mission to Jupiter

      Heist, E. K.; TRW Inc. (International Foundation for Telemetering, 1974-10)
      The Telecommunication subsystem for the Pioneer 10 and 11 spacecraft is described in terms of the exacting design requirements which have been met and the operational performance which has been achieved. Those features which are unique or novel and which contribute substantially to our knowledge of advanced techniques for future interplanetary missions, are emphasized. The discussion includes earth-pointing of the spacecraft high gain antenna by an on-board conical scan system, tracking, telemetry, and command functions at multi-million kilometer distances complicated by round trip communication delays of 90 minutes, and the versatility of special data formats which cater to certain instrument high rate sampling requirements during selected phases of the mission. With the successful flyby of the planet Jupiter by Pioneer 10 in December 1973, the technology and experience for much more ambitious, challenging, and complex missions to the outer planets has been demonstrated.
    • Telemetry in Underground Mines Using Leaky Transmission Line Nets

      Hu, A. H.; New Mexico State University (International Foundation for Telemetering, 1974-10)
      A wayside underground communication system using leaky electromagnetic transmission line nets is presented in this paper. This leaky line or cable enables radio wave propagation through tunnels and out-of-sight places via combined cable and atmospheric transmission. It is also an all-purpose communication link which provides telemetry, communication, traffic control, emergency capabilities, paging, TV surveillance, fire detection, and fire control.
    • Rendezvous Radar for Space Shuttle Orbiter Vehicle

      McQuillan, W. F.; Bologna, A. W.; Calabrese, D. M.; Rockwell International Corporation (International Foundation for Telemetering, 1974-10)
      To successfully complete many of the Space Shuttle Program proposed missions involving Orbiter rendezvous with orbiting satellites, some method of detecting and tracking remote targets is desirable. Several studies to establish the requirements for a rendezvous radar system indicated the feasibility of the concept. Extensive application of state of the art components is possible, and system parameters can be determined in a general sense to avoid impacting Orbiter development. Considerations of size and weight are necessary to the choice of any system, as well as the operational capabilities of the candidate. Two radar systems appeared to meet the requirements: a microwave radar and a laser radar. Although the laser radar was highly competitive, difficulty was encountered in assessing the operational risk of such a system. The microwave radar was therefore selected as the rendezvous sensor most suitable for Space Shuttle Program use.
    • Martian and Lunar Science with Remotely-Controlled Long-Range Surface Vehicles

      Jaffe, Leonard D.; Choate, Raoul; California Institute of Technology; TRW Systems Group (International Foundation for Telemetering, 1974-10)
      Science objectives are outlined for long surface traverse missions on Mars and the moon, with remotely-controlled roving vehicles. Series of candidate rover science payloads are proposed, varying in purpose, development needed, cost, and weight (35 to almost 300 kg). A high degree of internal control will be needed on the Mars rover, including the ability to carry out complex science sequences. Decision-making by humans in the Mars mission includes supervisory control of rover operations and selection of features and samples of geological and biological interest. For the lunar mission, less control on the rover and more on earth is appropriate. Operational problem areas for Mars include control, communications, data storage, night operations, and the mission operations system. For the moon, science data storage on the rover would be unnecessary and control much simpler.
    • An S-Band Telemetry Receiver System for Deep Space Applications

      Lampert, E.; Siemens AG (International Foundation for Telemetering, 1974-10)
      To receive the transmitted signals from the HELIOS space probe a S-band telemetry receiver system was built. Of this system the S-band telemetry receivers and the subcarrier demodulators are described. Measured values are presented. The S-band receiver includes a digitally implemented phase-locked-loop. Polarization tracking is possible in a two channel mode as well as in a single channel mode. In the subcarrier demodulator the subcarrier is demodulated before demodulating the RF-carrier. Good noise thresholds and low degradation is reached because remodulation is used in the subcarrier loop. The equipment works in a fully computer controlled station, this includes all aquisition procedures.
    • Odd-Bit Symmetric QASK

      Smith, Joel G. (International Foundation for Telemetering, 1974-10)
      Multiple-amplitude and phase-shift- keyed (MAPSK) signal set selection is influenced by factors such as average and/or peak signal-to-noise ratio for a given error probability, dynamic range of signal amplitudes, simplicity of generation and detection, and number of bit errors per adjacent symbol error. This paper compares two possible quadrature-amplitude-shift-keyed (QASK) signal sets for the case where the number of bits per symbol is odd (for the even-bit case, the square array is the only viable QASK choice). The symmetric QASK version outperforms the rectangular QASK set at a very modest implementation penalty. This permits symmetric QASK to be considered in future odd-bit system studies.
    • Method and Apparatus for Collecting Impact Test Data

      Mercer, Thomas C., Jr.; GM Proving Grounds (International Foundation for Telemetering, 1974-10)
      A flexible, powerful and interactive data collection system is described based upon state of the art instrumentation and computer aided digitization and processing. The result is a highly accurate and repeatable system capable of yielding reduced engineering plots within hours after an impact test has been conducted.
    • The Data Handling System of the Helios Probes

      Pabst, Dietrich; Digital Space Applications (International Foundation for Telemetering, 1974-10)
      The Helios probes A and B will have a maximum distance of 2AU from Earth. The typical requirements which are applicable to all deep space missions, especially decreasing link capacity, need a flexible data handling system. Taking the Helios probe as an example, it will be shown how the specific problems of data handling in deep space probes were solved from the technical standpoint. The system processes 4 selectable scientific formats at 8 to 4096 bit/sec with 320 subcommutated housekeeping channels, also to be transmitted in a separate engineering format. Simultaneously, a special format is stored cyclically with up to 16kbit in a 0.5Mbit memory, which can also be used for the storage of all the other data in an automatic sequence mode. Telemetry data are convolutional coded. Due to its flexibility and its multiplicity, the data handling system is a useful instrument for deep space missions.
    • The Viking Lander Telemetry Subsystem

      Patton, Victor V. C.; Martin Marietta Corporation (International Foundation for Telemetering, 1974-10)
      The Viking Program will place two orbiting spacecraft around Mars in the summer of 1976. Each spacecraft will contain a Mars soft lander. The Telemetry Subsystem is that group of electronics on the Viking Lander which interfaces all sources of operational and science data, stores and conditions that data, and provides it to the communications subsystem in appropriate form for RF transmission.
    • Simulation of PCM Data Utilizing a General Purpose Computer

      Shultenburg, K. G.; Ehrsam, E. E.; Control Data Corporation; Vandenberg Air Force Base (International Foundation for Telemetering, 1974-10)
      Due to the increased complexity and capabilities of modern missile telemetry systems, it has become increasingly difficult to provide an effective yet flexible simulation capability for the verification and validation of PCM decommutation systems. Control Data Corporation, under contract with the Space and Missile Test Center (SAMTEC) at Vandenberg Air Force Base, California, recently completed the development of a powerful and flexible simulation system utilizing a CDC 3300 computer. This Telemetry Decom Validation System (TDVS) now allows personnel to develop a simulated PCM data stream using a telemetry-oriented compiler to generate telemetry instructions. The compiled program can then be executed in a microprogrammable processor which generates the defined PCM stream through the interpretation of the specially designed instruction set output by the compiler. Data can be simulated at rates up to 2 megabits using any of the seven IRIG code conventions or Miller Code.
    • Firmware Controlled, High Speed, Random Data Acquisition Unit

      Trover, William F.; Teledyne Controls Co. (International Foundation for Telemetering, 1974-10)
      A firmware controlled, integrated data acquisition unit for computer controlled or standalone operation reduces the users Data Acquisition system programming task to preparation of a parameter list in IBM card deck format. Data cycle format generation is accomplished on a host computer which produces program tapes for the Data Acquisition system's field erasable PROM format memory. The completely random data system can be programmed for a wide spectrum of data cycle sizes. Cycle rate can be remotely controlled in flight permitting the operator to select any of 256 word rates from 244 WPS to 125,000 WPS. Analog and digital signal conditioning can be included in the unit which also provides excitation power for all conventional sensors. Sensor capacity is from 44 to 352 channels depending on the type of signal conditioning required for a specific application. Up to eleven of over 20 different types of signal conditioner/ multiplexer I/O modules, plus the overhead modules and the system power supplies, may be accommodated at one time in a package of less than 450 cu in. (4" x 8" x 14"). All I/O cards and modules regardless of type are interchangeable at any of the eleven I/O locations in the unit housing. A miniature data display module which can be mounted in any standard cockpit control console permits the pilot or test engineer to have real time access during flight to any data point in the system. Two or more data systems may be used at remote locations in the same aircraft in synchronized operation to accommodate higher data throughput rates without increasing recorder bandwidth requirements by recording separate serial data streams on parallel tracks of a single multi-track recorder. Ground support equipment permits sensor installation, calibration and system checkout without the need for aircraft ground power or finalization of a sampling format for a test flight. Interchanging the Standalone Timing Module with a Digital Processor Module permits the Data Acquisition Unit to become a remotely controlled bidirectional data processor of a larger system performing both data acquisition and control loop functions.
    • Frame Sync Acquisition for Biorthogonally Coded Data

      Levitt, Barry K. (International Foundation for Telemetering, 1974-10)
      The optimum procedure for locating a sync word periodically inserted in uncoded binary data received over a binary symmetric channel is based on the Hamming or bit distance metric. This paper addresses the corresponding frame sync problem for biorthogonally coded data transmitted over the additive white Gaussian noise channel. For conceptual convenience, the k-bit words from the decoder output are treated as "super symbols" from an alphabet of dimension 2ᵏ. It is argued that the optimum sync word search over the decoded data stream is based on a super symbol distance rule matched to the properties of the biorthogonally coded transmissions over the noisy channel. An optimum frame sync acquisition algorithm based on this distance rule is formulated, and its performance is investigated. As an example, the performance of this optimum frame sync algorithm is contrasted analytically with that of a Hamming distance algorithm operating on decoded (32, 6) biorthogonal data, a case of interest to some recent unmanned American space missions.
    • A Simple Preprocessor for Narrowband Omega Retransmission

      Raab, Frederick H. (International Foundation for Telemetering, 1974-10)
      Global distress location and search and rescue operation may utilize Omega VLF navigation signals for position determination. The rescue radio would retransmit the Omega signals to a satellite for relay to a search and rescue center, where the position of the retransmitter would be determined. Since only the phases of the Omega signal are required, preprocessing prior to retransmission can have several advantages, including reduced bandwidth, transmission ti.me, transmitter power, antenna size, and error rate. Both phase measurement and averaging can be accomplished by a simple counting phase detector. The characteristics of an Omega preprocessor using a set of counting detectors are described.
    • The Technical Characteristics of the German Telecommand Station for Deep Space

      Öttl, H.; Holl, H.; Institut für Flugfunk und Mikrowellen (International Foundation for Telemetering, 1974-10)
      The technical description of the Telecommand Station is based on the results of the final subsystem tests. Some outstanding results are illustrated by measured diagrams. The design of some station systems differs from those of the well known DSN stations. Presently, the station is equipped for command purposes only. Nevertheless, the station concept is such that a full-fledged deep space station can be achieved with a few additions, such as receiving and ranging equipment.
    • Appendix A: Thirteenth Annual Report of the Telemetering Standards Coordination Committee

      Muller, Ronald M. (International Foundation for Telemetering, 1974-10)
    • Space Shuttle Antenna Subsystem Design

      Ellis, H.; Cubley, H. D.; Symonds, Richard J.; Rockwell International; NASA/Lyndon B. Johnson Space Center (International Foundation for Telemetering, 1974-10)
      The unique nature of the Shuttle orbiter is that all of its systems must meet the design requirements of a spacecraft as well as the basic aircraft requirements for atmospheric flight. The Shuttle antenna system design, therefore, faces many unique problems. Some of the most significant of these problems include the interface with the Shuttle thermal protection system, the wide range of thermal extremes and rates to be encountered, the long life requirement, and the need for lightning protection. In addition, the radiation coverage requirements of some of the Orbiter antennas are complicated by the multiple requirement for operation during launch, from earth orbit to both ground station and relay satellites, and to the landing area during atmospheric flight. The unique engineering problems that result from these requirements will be described along with techniques that are planned for their solution.
    • The Laser Absorption Spectrometer: A New Remote Sensing Instrument for Atmospheric Pollution Monitoring

      Shumate, M. S.; Jet Propulsion Laboratory (International Foundation for Telemetering, 1974-10)
      An instrument capable of remotely monitoring trace atmospheric constituents is described. The instrument, called a Laser Absorption Spectrometer, can be operated from an aircraft or spacecraft to measure the concentration of selected gases in three dimensions. This device will be particularly useful for rapid determination of pollutant levels in urban areas.
    • Adaptive Bit Synchronizer

      Halpern, Peter H. (International Foundation for Telemetering, 1974-10)
      The motivation for adapting loop bandwidth is reviewed. The ideal loopwidth is shown to be a monotonic function of the ratio of two statistical measurements, namely the input SNR and the present uncertainty of proper phase. This is seen from a relatively simple viewpoint of how to combine independent measurements of the same quantity. Means for measuring the statistical quantities are described. Simple means for varying loop widths are described. Experimental results of the adaptive bit synchronizer are compared with a classical bit synchronizer.