• International Telemetering Conference Proceedings, Volume 10 (1974)

      International Foundation for Telemetering, 1974-10
    • Space Shuttle Communications-Wideband Direct Link Signal and System Design

      Batson, Bartus H.; Huth, Gaylord K.; Lyndon B. Johnson Space Center; Axiomatix (International Foundation for Telemetering, 1974-10)
      This paper describes the design of a wideband S-band communications link from the Space Shuttle Orbiter to a ground-based terminal. This link will be used for transmission of television, digital data (various rates), or analog data, and is of interest because of the presence of bandwidth, power, and hardware constraints. The procedure followed to arrive at an overall signal and system design is outlined, and system performance margins are presented for various operational configurations. Finally, the growth potential of this link for digital data transmission is discussed.
    • A Flexible Preprocessor for ERTS MSS Data

      Waltz, Edward L.; Bendix Aerospace Systems Division (International Foundation for Telemetering, 1974-10)
      The requirements to preprocess Earth Resources Technology Satellite (ERTS) multispectral scanner (MSS) data from its 24 channel tape format at real time rates can be met most efficiently by a parallel processor with a flexible interface for compatibility with a wide range of digital computers. The ability of the preprocessor and tape unit to playback data at programmable rates (real-time and half and quarter real-time) provides the additional ability to adjust preprocessing rate to optimize system throughput for several image processing computer system configurations, and processing modes. The MSS Data Interface described in this paper has been developed to meet these requirements for ERTS processing facilities of those nations which record ERTS data in the NASA-compatible format on 28 channel tape units. The first MDI which has been delivered to the Brazilian government is compatible with the Digital Equipment Corporation PDP-11 computer and can be operated in either a single or dual processor system configuration.
    • Time Response Simulation of the 1975 Viking Orbiter Digital Tape Recorder

      Mukhopadhyay, Asok K.; California Institute of Technology (International Foundation for Telemetering, 1974-10)
      The objective of this study is to verify and understand in depth the performance of the speed control (frequency loop) servo of the 1975 Viking Orbiter (VO75) digital tape recorder (DTR). The linear frequency-domain methods, such as the Bode Plot and the Root Locus, are inadequate in analyzing the VO75 DTR servo due to such dominant non-linear effects as servo signal limiting and static/dynamic Coulomb friction. The Time Response method employed in this study is written in the Continuous System Simulation Language (CSSL) for the Univac 1108 computer system. In order to demonstrate the power and flexibility of the graphic interactive simulation program, four aspects of system dynamics are interactively adjusted to arrive at a number of stable system configurations which has significantly different tape transport and/or summing amplifier gain, larger static/dynamic Coulomb friction, system lag than envisioned in the nominal design by linear methods.
    • Aeroflight Communications and RF Navaids

      Lilly, Douglas S.; Lyndon B. Johnson Space Center (International Foundation for Telemetering, 1974-10)
      The Space Shuttle Program concept of a low cost, reliable and reusable orbital vehicle has proven to be a driving function in systems design and integration. Extensive use of existing designs to satisfy these requirements has been effectively employed in the aeroflight systems. Appropriate planning and a careful appraisal of maturity, cost, performance, vehicle burdens, and operational flexibility were completed prior to a system choice. The aerial navigation and landing systems selected for the orbital vehicle are described and their interfaces with the control and navigation system discussed.
    • 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.
    • 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.
    • Flexibility Objectives for Real-Time Telemetry Processing Systems

      Rymer, J. W.; Naval Air Test Center (International Foundation for Telemetering, 1974-10)
      A generalized real-time telemetry processing system model is developed in four blocks: Demod/Synchronization, Data Channel, Processing/Control and Display. Flexibility objectives are stated for each block and illustrated with respect to the Navy's existing Real-time Telemetry Processing System (RTPS). Features and tradeoffs are discussed for each block along with references to the growing and significant body of such systems already existing and currently under development.
    • Use of Pseudo-Random PCM Tape Signatures for Telemetry Ground Station Validation

      Schoeck, K. O.; Pickett, R. B.; Vandenberg Air Force Base (International Foundation for Telemetering, 1974-10)
      This paper describes an improved tape recorder signature using pseudorandom PCM data. The use of the signature for telemetry ground station validation is discussed. Advantages over other techniques in common use are shown.
    • Volunteer Medical Engineers Can Aid Physicians and Hospitals in Telemetry Purchases and Tests

      Jackman, K. R. (International Foundation for Telemetering, 1974-10)
      Inasmuch as this 'ITC/USA/’74’ paper may be on a unique subject in the medical field, an attempt will be made to cover, with references and bibliography, sufficient background to identify some serious hospital and medical problems, with possible technical solutions. Most of these solutions involve the use of trained and experienced Medical (or Clinical) Engineers and Biomedical Equipment Technicians (BMET) in hospitals, clinics, and equipment servicing laboratories. The use of volunteer 'Med. Engrs’, as a public-service of the ACTION groups in each city, will be proposed to solve the local hospital needs for technical performance specifications in purchasing 'vital’ medical instruments, such as the 'ECG’ telemetry systems common to local hospitals. Even greater need for low-cost medical-care exists in many 'developing’ countries, such as India. The writer makes a plea, using Med. Engrs. methods developed and successfully used in Los Angeles in the last three-years, to bring graduate (medically-oriented and trained) engineers, seeking employment into hospitals in their own towns. A 'pilot’ program will be reviewed, using 'ACTION’ professional volunteers in San Diego hospitals, to set an example for 'Med.Engrs’ retrained in Madras, India, to enter their local hospitals, and thereby select techniques for use in other Indian cities.
    • Comparison of Viterbi and Sequential Decoding with a Noisy Carrier Reference

      Hofman, L. B.; Lumb, D. R.; NASA Ames Research Center (International Foundation for Telemetering, 1974-10)
      Performance of convolutionally encoded telemetry systems with Viterbi decoding or sequential decoding is well understood for the additive white Gaussian noise channel with coherent detection of bi-phase-shift-keyed signals. Significant degradation from ideal performance can occur due to correlated noise resulting from low signal-to-noise ratios in the receiver carrier tracking phase-locked loop. Performance at the lower telemetry data rates on the two Pioneer Jupiter deep space probes provides examples of the effect of correlated noise on a sequential decoding system. Performance degradation needs to be quantified as a function of carrier signal-to-noise ratio (P(c)/N(o)2B(lo)) and carrier-tracking- loop-bandwidth-to-symbol-rate ratio (B(l)/R(s)) in order to provide design and analysis information on such effects. Analytical modeling is extremely difficult, particularly where B(l)/R(s) is neither very large nor very small.
    • 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.
    • The Shallow Sea-A New Challenge to Telemetry and Communication

      Werner, Edgar; Inter American University of Puerto Rico (International Foundation for Telemetering, 1974-10)
      A preliminary study of the environmental and operational parameters requisite to the design and development of low cost simplified communication and telemetry devices usable in the shallow waters of continental shelves is presented. Specific requirements peculiar to the needs of Ocean Resource Utilization Programs in underdeveloped countries lacking both economic and technological capabilities for using current off the shelf devices are outlined. The environment in which this equipment must operate is defined, first physically and then subjectively, and operational aspects of this type of endeavor are described in terms of the individuals involved. Finally, some design parameters are suggested with a general consideration of the potential market as these programs increase in scope and number. It is hoped that feedback from this paper will generate future specific designs and quantitative criteria on which to base more detailed development work.
    • Computer Controlled Radio Information System for Public Vehicle Operations

      Go, G. Bie; AEG-Telefunken (International Foundation for Telemetering, 1974-10)
      Radio control centers for Public vehicle operations has long been an essential instrument to control and monitor schedules and operations. However, due to the rapid development of city and urban traffic the capacity limit of the small amount of voice channels is already reached, especially during rush hours. Moreover the dispatchers are overburdened, so that adherence to schedule and safe operations cannot be guaranteed. Data communications is the means to increase the efficiency and the capacity of the existing system. AEG-TELEFUNKEN has conceived an advanced system TELETRANS utilizing computer control and radio monitoring. This system makes improved use of the existing channel capacity without infringing on current FCC regulations. Through the use of co-channel transmission, which is a special type of transmit diversity, large areas with diameters up to 40 km (25 mi.) can be covered. This system is flexible, so that requirements of small and large public transportation authorities can be fulfilled economically.
    • 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.
    • 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.
    • 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.
    • 117.6-Kilobit Telemetry from Mercury In-Flight System Analysis

      Evanchuk, V. L.; California Institute of Technology (International Foundation for Telemetering, 1974-10)
      This paper discusses very specifically the mode of the Mariner Venus/ Mercury 1973 (MVM'73) telecommunications system in the interplexed dual channel 117.6 kilobits per second (kbps) and 2.45 kbps telemetry. This mode, originally designed for only Venus encounter, was also used at Mercury despite significantly less performance margin. Detailed analysis and careful measurement of system performance before and during flight operations allowed critical operational decisions, which made maximum use of the system capabilities.
    • 117.6 Kilobit Telemetry from Mercury-A Major Deep Space Telecommunication Advance

      Clarke, Victor C.; California Institute of Technology (International Foundation for Telemetering, 1974-10)
      For nearly eight hours on March 29, 1974, Mariner 10 transmitted imaging telemetry in real time at 117.6 Kbps from Mercury. During this time, 562 very high quality frames were received, even though the bit error rate was only about 1 in 40. The transmission of 117.6 Kbps from Mercury is a magnificent telecommunications achievement, which permitted an order of magnitude increase in imaging science data return. The Mariner 10 imaging scientists' requirements, simply stated, were to obtain maximum area coverage at highest spatial resolution. More precisely, they desired photomosaics which were equivalent to the best earth-based pictures on the Moon, i.e., about 1 km resolution. The purpose of this paper is principally to relate the methods by which these "desirements" were translated into measurable telecommunication system requirements and some of the attendant tradeoffs. Additionally, same of the steps taken to achieve their goal are recited.
    • Space Shuttle Communications and Tracking System

      Batson, Bartus H.; Johnson, John H.; Lyndon B. Johnson Space Center (International Foundation for Telemetering, 1974-10)
      This paper provides an overview of communications and tracking for the Space Shuttle Program. The Shuttle Program itself is briefly described, and communications and tracking requirements and capabilities are discussed for the various phases (ascent, on-orbit, and reentry/ landing) of a Shuttle mission.