• The Helios Spacecraft/Ground Telecommunications System Concept

      Hertlein, H. P.; Gesellschaft fuer Weltraumforschung (International Foundation for Telemetering, 1974-10)
      The U. S.-German joint Helios Program is briefly presented with emphasis upon the Spacecraft Telecommunications System design and Ground Tracking and Data System. The design constraints for the radio system, and some tradeoff considerations germane to the Helios radio system are discussed. The block diagram, major performance parameters and some test results are given as bases for the understanding of more detailed telecommunications system discussions.
    • 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.
    • A Coding Algorithm for Random Access Satellite Systems

      Wu, W. W. (International Foundation for Telemetering, 1974-10)
      In satellite communications systems, when a code-division scheme is desirable for random multiple access, specific codes must be constructed for the users in the system to share the same satellite channel. This paper develops a coding algorithm for such purposes by means of a binary matrix. Step-by-step procedures are separately described. An example demonstrates the usefulness of the algorithm, and its advantages and disadvantages are discussed. Finally, a problem for future work is suggested.
    • 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.
    • 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.
    • On-Board High Frequency Data Processing

      Maschhoff, Robert H.; Gultron Industries (International Foundation for Telemetering, 1974-10)
      On-board processing of high frequency analog data, such as that derived from vibration and acoustic sensors, offers the telemetry engineer three highly significant advantages over traditional fm/fm transmission of such data. When combined with PCM techniques the result is (1) bandwidth compression, (2) single rf data link, and (3) substantially higher data accuracy. In this processing technique only data representative of the power spectral density of the sensed waveform is transmitted to the ground station. By shifting the data processing function to the on-board telemetry system and transmitting only the processed data, the required transmission channel bandwidth is greatly reduced. As a result of this bandwidth compression the high frequency data can be pulse code modulated. Two significant advantages thereby ensue. The first is that data from multiple sources may now be transmitted over a single rf data link. The second advantage is that the data accuracy is greatly increased.
    • 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.
    • Evolution of the Douglas Flight-Test Data System

      Crowley, L. D.; Douglas Aircraft Company (International Foundation for Telemetering, 1974-10)
      The process of developing new techniques and systems for the purpose of flight-test data acquisition, communication, and processing is, in fact, an evolutionary one. It is filled with potential mutations formed when an orderly or direct path is not taken in any of supporting disciplines or when the capabilities of one link greatly exceed those of another. The rigid design philosophy that made the Douglas system so successful in support of numerous test programs has had both a negative and positive effect of limiting, or at least slowing, the future growth in flexibility. Upgrading the system with new hardware and software must be accomplished in a manner that does not degrade the existing performance and throughput capabilities while making room for the new species to evolve. Problems have been minimized by placing the development of the acquisition and processing systems under common management and, in turn, having this group accountable to the project users of the system. Constant feedback between system developers and users has ensured a degree of adaptability to the hostile environment of test program costs and schedules.
    • The Antenna System of the Helios Solar Probe

      Horwath, L.; Liesekötter, B.; Tymann, G.; Messerschmitt-Boelkow-Blohm GmbH. (International Foundation for Telemetering, 1974-10)
      For the Helios solar probe a complete antenna system was developed and manufactured which is suitable for the various mission requirements, as near earth phase varying aspect angles, close sun flyby and maximum distance of 3,0. 10⁸ km with spin axis orientation perpendicular to the ecliptic. The near earth phase requirements were covered by a low gain antenna system with an isotropic radiation pattern. After the rough orientation of the spin axis a medium gain antenna with an omnidirectional radiation pattern will be used. After final orientation of the spin axis perpendicular to the ecliptic plane a high gain antenna with a despun wire grid reflector will be used for the telemetry link. By switching devices and/or hardwire connections the antenna systems are partly redundant in order to get the required high reliability. The maximum operating temperature range of the antenna system is + 200° to - 200°C.
    • Capacity of Noncoherent MFSK Channels

      Bar-David,I.; Butman, S. A.; Klass, M. J.; Levitt, B. K.; Lyon, R. F.; Jet Propulsion Laboratory (International Foundation for Telemetering, 1974-10)
      This article computes the capacity of a noncoherent multifrequency-shift-keying channel as a function of the number of orthogonal signals, M, and the predetection signal-to-noise ratio, ST/N₀, for three basic receiver types; these are hard decision, unquantized (optimum), and quantized (soft decision). Computational cutoff rates for sequential decoding are also computed.
    • The Future of Real Time Telemetry Systems

      LeCann, Raymond P.; Grumman Data Systems Corporation (International Foundation for Telemetering, 1974-10)
      This paper briefly outlines the development of real time data processing systems and discusses the techniques used in present systems to bring full power of computer facilities to the systems user. While discussing existing systems, future user requirements are examined and the application of recent technology to these needs is investigated. Software systems, hardware techniques and systems management are reviewed so that future systems design may be responsive to the human, as well as the technical elements of vehicle testing.
    • 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.
    • German Telecommand Station-The Dynamic Behaviour of the Steel Structure and Its Drive and Control System

      Eschenauer, H. A.; Schwarz, R. K.; Krupp Industrie- und Stahlbau; Siemens AG, Unternehmensbereich Energietechnik (International Foundation for Telemetering, 1974-10)
      The mechanical equipment and steel structure of large antennas represents a vibratory system made up of very many elastically coupled masses. Together with the drive control equipment, this complex system has to meet certain requirements with regard to pointing accuracy, turning range, turning speed, and acceleration. Prior knowledge of the dynamic behaviour of the whole control loop is essential to avoid unpleasant surprises at the commissioning stage.
    • Atmospheric Monitoring Using Infrared Heterodyne Radiometry

      Peyton, Bernard J.; Cutler-Hammer (International Foundation for Telemetering, 1974-10)
      Atmospheric constituents have unique vibrational-rotational signature lines within the infrared spectrum and the signature intensities and line shapes vary with the constituent concentration and the atmospheric density. The recent development of stable, single frequency, single-mode laser local oscillators and nearly quantum-noise-limited heterodyne receivers have permitted the development of infrared heterodyne radiometers (IHR's) which provide good sensitivity and excellent specificity for the remote examination of individual atmospheric constituent signature lines. A 9 to 11 μm IHR employing a CO₂ laser local oscillator has been developed and can be used to resolve the spectral signature of atmospheric constituents such as SO₂, O₃ C₂H₄, and NH₃. The IHR has a bandwidth of 100 MHz (33 x 10⁻³ cm⁻¹) and a minimum detectable power spectral density of 5.4 x 10⁻²⁴ W/Hz for a 1-second integration time. For atmospheric monitoring applications the IHR telescope collects the thermal energy radiating from the earth at: (1) a clear spectral window, and (2) a spectral region in which the signature lines of the constituent gases at various layers of the atmosphere will be energized by the upwelling thermal radiation. When the vertical temperature distribution of the atmosphere is known, the concentration of the atmospheric constituent gas can be determined as a function of altitude from the radiance data collected at the IHR using an iterative mathematical technique.
    • Carrier Tracking, Bit Synchronization, and Coding for S-Band Communications Links

      Odenwalder, J. P.; LINKBIT Corporation (International Foundation for Telemetering, 1974-10)
      This paper presents the results of a study of the performance of Viterbi-decoded convolutional codes in the presence of nonideal carrier tracking and bit synchronization. A constraint length 7, rate 1/3 convolutional code and parameters suitable for the Space Shuttle coded communications links are used. Mathematical models are developed and theoretical and simulation results are obtained to determine the tracking and acquisition performance of the system. It is shown that the combined E(b)/N(o) degradation due to nonideal carrier tracking and bit synchronization over that required for the ideal tracking case can be held to less than 1.5 dB and that combined carrier tracking and bit timing can be acquired in only a few seconds for the parameters and operating ranges of the Space Shuttle coded communications links.
    • Experientially Guided Robots

      Merriam, E. William; Becker, Joseph D.; Bolt Beranek and Newman Inc. (International Foundation for Telemetering, 1974-10)
      This paper argues that an experientially guided robot Is necessary to successfully explore far-away planets. Such a robot is characterized as having sense organs which receive sensory information from its environment and motor systems which allow it to interact with that environment. The sensori-motor information which it receives is organized into an experiential knowledge structure and this knowledge in turn is used to guide the robot's future actions. A summary is presented of a problem solving system which is being used as a test bed for developing such a robot. The robot currently engages in the behaviors of visual tracking, focusing down, and looking around in a simulated Martian landscape. Finally, some unsolved problems are outlined whose solutions are necessary before an experientially guided robot can be produced. These problems center around organizing the motivational and memory structure of the robot and understanding its high-level control mechanisms. This paper discusses a project which is attempting to develop the "mind" of' a robot which will be capable of experiencing its environment, storing sensori-motor information, and then using its accumulated knowledge to guide its future actions. In Section I, we describe the sort of behavior that an experientially guided robot might exhibit, and we give some reasons why we might want such a thing. Then, in Section II, we discuss the current state of our project, and in Section III we indicate some important issues that are as yet unresolved.
    • The Impact of Robots on Planetary Mission Operations

      Hooke, A. A.; Larman, B. T.; Whitney, W. M.; California Institute of Technology (International Foundation for Telemetering, 1974-10)
      For reasons of efficiency and safety, unmanned roving vehicles sent to explore remote planetary surfaces must carry out some of their tasks without step-by-step human control. To realize the benefits that such semiautonomous machines can provide will require some changes in how planetary missions axe presently planned and conducted. Specifically, mission profiles will have to be based on tasks or functions rather than sequences of timed events, scientists will have to be more directly involved in the control of their instruments, and present ideas concerning spacecraft safety, testing and simulation of vehicle performance, telemetry design, and ground-system implementation must be reexamined.
    • 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.
    • Analysis and Test Results of a Hybrid PCM/FM-subcarrier Baseband Multiplex on an FM Carrier

      Nichols, M. H.; The Aerospace Corporation (International Foundation for Telemetering, 1974-10)
      Engineering formulae have been developed for estimating the performance of a telemetry system utilizing an NRZ PCM multiplex plus an FM/FM multiplex frequency modulating a carrier. These formulae have been checked against a laboratory simulation and the agreement is within 1 dB for the PCM and 1.8 dB for the FM/FM. About 1 dB of the 1.8 dB is tentatively accounted for on the basis of lack of symmetry of the carrier predetection (IF) filter used.
    • Some Simulation Results for Convolutional Codes Over a PCM/FM Fading Channel

      Grant, T. L.; Hofman, L.; NASA Ames Research Center (International Foundation for Telemetering, 1974-10)
      NASA is now actively planning entry probe missions for the outer planets. Such an entry probe requires a new telemetry link design. A probable modulation for this link is a continuous phase, narrow-band FSK (or PCM/FM), and this paper reports on simulations which can be used to estimate convolutional code performance with mild fading on such a channel. Simulated decoding has been performed for a range of signal-to-noise ratios on the PCM/FM channel with various fading characteristics.