• Differential Sampling for Fast Frequency Acquisition Via Adaptive Extended Least Squares Algorithm

      Kumar, Rajendra; California Institute of Technology; California State University (International Foundation for Telemetering, 1987-10)
      This paper presents a differential signal model along with appropriate sampling techniques for least squares estimation of the frequency and frequency derivatives and possibly the phase and amplitude of a sinusoid received in the presence of noise. The proposed algorithm is recursive in measurements and thus the computational requirement increases only linearly with the number of measurements. The dimension of the state vector in the proposed algorithm does not depend upon the number of measurements and is quite small, typically around four. This is an advantage when compared to previous algorithms wherein the dimension of the state vector increases monotonically with the product of the frequency uncertainty and the observation period. Such a computational simplification may possibly result in some loss of optimality. However, by applying the sampling techniques of the paper such a possible loss in optimality can be made small.
    • The Voyager-2 Neptune Encounter

      Kosmann, William J.; The California Institute of Technology (International Foundation for Telemetering, 1987-10)
      Mankind's first in situ exploration of the planet Neptune and its moons, rings, and magnetosphere will occur during the summer of 1989. The Voyager system was designed to explore Jupiter and Saturn. However, Neptune is three times farther away than Saturn. The major science objectives and telecom link distance generate unique telecommunications requirements. Among these are conversion of the Deep Space Network's (DSN) 64 meter antennae to 70 meter antennae, arraying of the Very Large Array (VLA) with the DSN antennae at Goldstone CA, use of the 64 meter radio-telescope at Usuda, Japan, and new on-board spacecraft data control software. In addition, telecom improvements first made for the Uranus encounter, including parallel operation of the spacecrafts redundant data control processors, on-board spacecraft data compression software, and on-board data encoding hardware and software, will also be used for the Neptune encounter.
    • Data Relay System for Space Shuttle and Payload Pre-Launch Checkout

      O'Donnell, Hugh B.; Wise, Thomas E.; Ngo, David Q.; GSFC; BFEC (International Foundation for Telemetering, 1987-10)
      Engineering requirements and design characteristics of the coherent throughput relay system which supports East Coast pre-launch checkout of NASA's Space Shuttle and its Payloads are presented. The Relay system is required to provide communications through NASA's Tracking and Data Relay Satellite System for the Shuttle and Payload-Users while they are encapsulated in the launch preparation facilities at the John F. Kennedy Space Center and the Eastern Test Range, Florida. The Relay system is required to be transparent to its users' data at all rates up to three MB/s at S-band and 300 MB/s at Ku-band. Noise and group-delay distortion are major contributors to wide band RF signal degradation. These were major factors in the Relay system design. Antenna design, pointing angle and location were constrained by the need to maximize end-to-end RF signal isolation at both S-band and KU-band, simultaneous forward and return frequencies. System characteristics and link analysis are also presented. In addition, a similar Data Relay located at Vandenberg Air Force Base is briefly described.
    • An Inexpensive S-Band Angle Pointing Technique for Steering a Narrow Beam Ku-Band Antenna

      Line, Larry; Hager, Fred; Hanson, Duke; Kral, Kevin; Moss, Robert; Goddard Space Flight Center; Motorola, Inc.; Honeywell-Speery Space Systems; Westinghouse Electric Corporation (International Foundation for Telemetering, 1987-10)
      A recently tested antenna pointing control system for gimbaled antennas has been developed. A modified TDRSS user transponder produces pointing error signals from the S-band forward link which in turn drive the Steering Control Electronics (SCE) to precision steer a S-/Ku-band Data and S-band Tracking (KDST) planar array. A successful test of the pointing and data handling capabilities is described and plans for further tests, incorporating additional refinements, are presented.
    • D-1 and DCRSi: The Present and the Future

      Wood, Tracy G.; Ampex Corporation (International Foundation for Telemetering, 1987-10)
    • Binary Decision Machines: Alternative Logic for Telemetry Control

      Croson, E.; Howard, J.; Jue, L.; University of California, Santa Barbara (International Foundation for Telemetering, 1987-10)
      A Binary Decision Machine (BDM) is described as a means of achieving logical control of data acquisition equipment and telemetry systems. The basic architecture of a BDM is initially presented followed by a description of its implementation as a Very Large Scale Integration (VLSI) device. Performance characteristics, programming, and ease of use as a controller are then presented via actual applications. The results of these endeavors led to a means of digitizing and extracting doppler data in a missile telemetry system.
    • The Generic Data Capture Facility

      Connell, Edward B.; Barnes, William P.; Stallings, William H.; Goddard Space Flight Center (International Foundation for Telemetering, 1987-10)
      The growing complexity of space science missions is causing a dramatic increase in the data rates and volumes from spaced-based experiments, and the ground operations functions associated with handling data from these missions are growing in complexity consistent with this increase. A key requirement on the systems that provide data handling support is to control operations costs carefully while providing high-quality data capture functions. One approach to meeting this particular objective that has been taken at the Goddard Space Flight Center has been to initiate the development of a Generic Data Capture Facility (GDCF) that can provide data capture support for a variety of different types of spacecraft. The GDCF is emerging through a blend of new system development and evolution of existing systems, and when complete, it will have the capability to support the two major data formatting schemes (packet and Time-Division Multiplexed (TDM)). The specific implementations are designed to support the Gamma Ray Observatory and the Upper Atmosphere Research Satellite, but the GDCF will provide the baseline system to support various new missions as they emerge.
    • Expert Systems in Data Acquisition

      McCauley, Bob; Telemetry Systems Operation (International Foundation for Telemetering, 1987-10)
      In an Independent Research and Development (IR&D) effort, the Telemetry Systems Operation (TSO) of Computer Sciences Corporation (CSC) sought to determine the feasibility of using Artificial Intelligence (AI) techniques in a real-time processing environment. Specifically, the use of an expert system to assist in telemetry data acquisition processing was studied. A prototype expert system was implemented with the purpose of monitoring F15 Vertical Short Take Off and Landing (VSTOL) aircraft engine tests in order to predict engine stalls. This prototype expert system was implemented on a Symbolics 3670 symbolic processor using Inference Corporation's Artificial Reasoning Tool (ART) expert system compiler/generator. The Symbolics computer was connected to a Gould/SEL 32/6750 real-time processor using a Flavors, Inc. Bus Link for real-time data transfer.
    • Data Handling System for IRS

      Rajyalakshmi, P. S.; Rajangam, R. K.; Digital Systems Division (International Foundation for Telemetering, 1987-10)
      The three axis stabilized Indian Remote Sensing Satellite will image the earth from a 904 Km polar - sun synchronous orbit. The payload is a set of CCD cameras which collect data in four bands visible and near infra-red region. This payload data from two cameras, each at 10.4 megabits per sec is transmitted in a balanced QPSK in X Band. The payload data before transmission is formatted by adopting Major and Minor frame synchronizing codes. The formatted two streams of data are differentially encoded to take care of 4-phase ambiguity due to QPSK transmission. This paper describes the design and development aspects related to such a Data Handling System. It also highlights the environmental qualification tests that were carried out to meet the requirement of three years operational life of the satellite.
    • A Technical Comparison of Frequency and Phase Modulation Relative to PCM Data Transmission Systems

      Lovejoy, David; Physical Science Laboratory (NMSU) (International Foundation for Telemetering, 1987-10)
      Direct experience in the design and developement of airborne telemetry systems utilizing both principles of modulation. System level analysis of receiver phase coherency, bit sync error codes, data band width, transmission efficiency and overall system complexity. High reliability, miniaturized packaging and HI-G survivability will be stressed as well as illustrated.
    • A Distributed Systems Approach to Real-Time Data Acquisition and Monitoring

      Fidell, Sanford; Fortmann, Thomas; Moss, Peter; BBN Laboratories, Inc. (International Foundation for Telemetering, 1987-10)
    • Spectrum Utilization for the International Space Station Communications and Tracking Systems

      Novosad, Sidney W.; Johnson Space Center (International Foundation for Telemetering, 1987-10)
      Over its lifetime, the international Space Station Program will use a variety of communications and tracking systems which could span the frequency spectrum from VHF to optical wavelengths. Primary communications traffic will initially occur in the S-band and Ku-band regions. Tracking will initially consist mostly of L-band satellite links. As the demand for more C&T services increases in the growth phase, use of millimeter and optical wavelengths will be required. Although many issues remain to be resolved, the most significant interference concern at present is that of Ku-band space/space links between co-orbiting Space Station elements.
    • An Asynchronous Digital Interface for SLAT Telemetry

      Drescher, Leo; Martin Mariette Orlando Aerospace (International Foundation for Telemetering, 1987-10)
      This paper describes telemetry used in the Supersonic Low Altitude Target (SLAT) built for the U.S. Navy by Martin Marietta. Feeding digital inputs directly to a pulse code modulation (PCM) encoder, bypassing the analog-to-digital (A/D) converter, and injecting into the output PCM wavetrain is well known. Various techniques for accomplishing this have been reported; however, they all have time correlation and synchronization problems. The system to be described involves asynchronous data transfer from the digital computer to the PCM encoder. The system uses a dual-port random-access memory (RAM) to effectively decouple the computer output, which is running synchronously on its 6 MHz clock, from the PCM wavetrain, which is running at 128 kilobits per second. Data from the computer is being "written into" the RAM simultaneously while data is being "read out." Contention arbitration prevents loss of data when read and write ports of the same address are activated. A "forbidden code" provides a special code when the computer is not connected or is producing all zeros.
    • Telemetry Bus Linkage with a High-Speed Ring Architecture: An Approach Analysis

      Nicolo, John M.; Aydin Monitor Systems (International Foundation for Telemetering, 1987-10)
      The growing complexity of space vehicle, aircraft, and missile test data analysis requiring larger data volumes and higher data rates, in conjunction with real-time analysis and display, calls for a new approach in telemetry system bus architecture. To meet these needs AMS developed the Mercury Bus, and a high-speed ring architecture capable of linking up to 7 Mercury Busses together without reducing targeted bus bandwidth of 6 MWPS. The Mercury Bus is a 48 bit parallel bus consisting of 32 data bits, and 16 "token" or address bits. It supports setup or real-time transfers between multiple master/slave modules within a chassis. The ring architecture consists of Bus Arbitrator, Repeater, Terminator Modules (BAT's) connected together by circular unidirectional read and write pipelines. The BAT arbitrates bus mastership, repeat's intra-chassis transfers and provides signal termination for the Mercury Bus. The pipelines relay bus transfers to successive chassis within the ring. This architecture currently supports up to 7 chassis or 112 modules per system. The ring architecture has met and exceeds initial design criteria with transfer rates measured in excess of 8 million words-per-second. It performs sustained high-rate data transfers while maintaining the data integrity and reliability associated with real-time telemetry. This architecture is well suited for systems with multiple input streams and high data processing requirements. Overall performance is attributed to the low noise characteristics of a controlled impedance backplane; implementation of module front end standardized bus interfaces; and the Bus Arbitrator, Repeater, Terminator module.
    • Interagency Arraying

      Cox, Henry G.; California Institute Technology (International Foundation for Telemetering, 1987-10)
      Voyager ground aperture requirements for Neptune encounter in August 1989 exceed the expected capabilities of the Jet Propulsion Laboratory's Deep Space Network (DSN) 70- and 34-meter antennas. Agreements have been consummated with the National Science Foundation to array the National Radio Astronomy Observatory's Very Large Array in New Mexico and with the Commonwealth Scientific and Industrial Research Organization's Parkes Radio Telescope in Australia with the DSN. This technique, which was demonstrated during Voyager's Uranus encounter, will provide a greater return of imaging and non-imaging science data. The arrays consist of the normal facility receiving equipment at each location, augmented by special receiving, combining, recording, and monitor and control equipment. This equipment has been designed, is being implemented, and will be operated during the Neptune encounter to effectively double the available antenna aperture over the western United States and Australia.
    • Effects of Co-Channel Interference with Frequency Offset on PSK Signals

      Raghavan, Srini; The Aerospace Corporation (International Foundation for Telemetering, 1987-10)
      The sharing of C-band between microwave terrestrial and satellite communication systems invariably introduces interference from one system into the other. Such co-channel interference becomes even more important in satellite receive stations with smaller antennas and must be minimized to achieve system performance objectives. In this paper, co-channel interference due to two TD2 (FDM/FM) carriers into a satellite receive system, receiving binary phase-shift keyed (BPSK) signal, is considered. It is shown that the frequency offset of the TD2 carriers from the BPSK carrier can be used to minimize co-channel interference effects. Equations are given which compute the bit error rate (BER) of BPSK signals in the presence of an interfering unmodulated carrier. They are followed by some results due to TD2 carrier interference.
    • ReConTTA: A State-Of-The-Art Telemetry Tracking System

      Morton, Stephen G.; United States Air Force (International Foundation for Telemetering, 1987-10)
      The purpose of this paper is to present and discuss key features of a Remotely Controllable Telemetry Tracking Antenna (ReConTTA) system which, truly, represents the current state-of-the-art. The ReConTTA system is planned to support flight testing of all current and future generation aircraft at the Air Force Flight Test Center (AFFTC), Edwards Air Force Base, California. System features to be discussed include: (1) The Antenna Group including Radial Scanning (RADSCAN). (2) The Local Control Group and its interface with the down converting, r-f switching, receiving, diversity combining, and microwave data-link equipment. (3) The Remote Control Group and its interface with microwave and ground station processing equipment. Several examples will be presented, illustrating the capabilities of the ReConTTA system, including the following: (1) Remote control operations utilizing computer control. (2) Broadband frequency coverage from 1435-2400 Mhz. (3) Low tracking angle performance.
    • An Efficient Decoding Algorithm for Long Convolutional Codes

      Ng, Wai-Hung; Hsieh, Ning-Ning; The Aerospace Corporation (International Foundation for Telemetering, 1987-10)
      Optimum decoding of long convolutional codes is an attractive technique to achieve reliability of communication. However, conventional decoding algorithms are very sensitive to variations in operational conditions, and such algorithms are also difficult to adapt to high-data-rate systems. Based on distance properties of code and pattern analysis of test-error sequences, a new decoding algorithm is derived that does not have those disadvantages.
    • Recent Advance in Instrumentation Recording Technology in China

      Xinnong, Zhang; Beijing Research Institute of Telemetry (International Foundation for Telemetering, 1987-10)
      In this paper the YJ2-4 portable tape recorder, which was recently developed by Beijing Research Institute of Telemetry, is described, and some of its major design features are discussed. YJ2-4 is a high performance, wideband, and microcomputerbased recorder/reproducer system, and compatible with existing international standards in the field of instrumentation tape recording (ISO 6068-1985 and IRIG 106-86).
    • Data Acquisition & Recording System

      Gustin, Thomas W.; Systems Research Laboratories, Inc. (International Foundation for Telemetering, 1987-10)
      The Data Acquisition & Recording System (DARS) is a totally self-contained, high technology data conversion and acquisition system, especially designed for unconstrained and hostile test environments. This system's initial use is for the Advanced Dynamic Anthropomorphic Manikin (ADAM), a test article for acquiring physical event and performance information from both the fully instrumented manikin which contains this system, and from the advanced technology CREST ejection seat upon which it rides. The ADAM development program was sponsored by the Air Force's Aeronautical Systems Division, Life Support Systems Program Office, and the Armstrong Aerospace Medical Research Laboratory. This paper presents the system level design of the DARS with emphasis on techniques used to solve special applications problems including survival in high 'G' tests, high speed computer controlled acquisition activities emulating PCM functions, simultaneous Telemetry and onboard data storage techniques, special sensing techniques, and a custom generic signal conditioning front end system. The presentation will conclude with several types of test environments and scenarios chosen to demonstrate the capabilities of the DARS, including the ADAM application.