• A 4 Mbps Digitizer with 100 kHz Signal Bandwidth

      Enterkine, Robert; Naval Weapons Center (International Foundation for Telemetering, 1987-10)
      This paper presents a non-standard digitization scheme which samples the data asymmetrically in order to maximize data bandwidth. Two frame sychronization words are utilized in a separated manner to permit their replacement with the average value of adjacent data words during the decommutation process.
    • Accommodating Telemetry Data Acquisition Systems

      Shelley, Larry; McCauley, Bob; Computer Sciences Corporation (International Foundation for Telemetering, 1987-10)
      The Telemetry Systems Operation (TSO) of CSC in Lompoc, California, has been developing telemetry systems since October 1981. Three major turnkey systems have been developed as well as several smaller derivative systems. Each system, built for a different end-user, was custom fit to support unique requirements and often represented several different techniques for accommodating similar problems within different system architectures. This paper describes the evolution of TM system architectures developed by TSO Lompoc, and the special engineering problems solved in the course of their development to provide the user with accommodating telemetry systems that are responsive, expandable, and cost-effective.
    • Advanced Joint Test Assembly (JTA) Telemetry System

      Stimmell, K. G.; Sandia National Laboratory (International Foundation for Telemetering, 1987-10)
      We design telemetry systems which instrument weapons in the Joint DoD/DOE flight test program. These telemetry systems gather data which can be used to determine if a weapon functioned as intended. Traditionally, a telemetry system has been designed to fit the individual requirements of each of the many weapons which have gone into production. The process of defining requirements, designing the system, and getting it into production with the quality assurance demanded of all weapon components takes considerable time, manpower, and money. Due to the rapid advancement of electronics and computer technology, these telemetry systems and their production testers become difficult to support if the weapon service time is extended or if aging test equipment breaks down. We are designing a telemetry system to support new programs for the next decade and to replace old telemetry systems which can no longer be produced. This multi-system Joint Test Assembly (JTA) is being designed to be modular, flexible, and testable. New techniques for increasing reliability, such as redundancy, error detection and correction, and microprocessor recovery will be employed. The requirements for each program can be met by choosing the necessary circuitry from a "shopping list" and packaging to meet the mechanical constraints for each system. Production specifications and test equipment will be in place to support any telemetry which is composed of the previously-designed modules. Modifications of hardware and software to support individual requirements will be kept to a minimum. We expect this new approach to telemetry system development to significantly reduce cost and lead time for every program on which it is employed. The use of this telemetry system on multiple programs should also enhance reliability.
    • 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.
    • 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.
    • D-1 and DCRSi: The Present and the Future

      Wood, Tracy G.; Ampex Corporation (International Foundation for Telemetering, 1987-10)
    • 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.
    • A Data Handling and Linking System for all of NASA's Near Earth Space Missions

      Hockensmith, R.; NASA/GSFC (International Foundation for Telemetering, 1987-10)
      A modularized data handling and linking system is evolving that will meet all of NASA's low earth orbiting space needs. The system is comprised of three major subsystems: (1) Data management (three networks; 300 Mbps to 20 Mbps, 20 Mbps to 3 Mbps, and 3 Mbps to 125 bps); (2) RF (antennas and microwave components); and (3) antenna control. Representative system components, approximately 70% of a total system, have been tested operating through the NASA Tracking and Data Relay Satellite System in May 1987. The modularized concept and data bandwidth transitions of the data management subsystem utilizes recently developed flight components along with developmental models that results in a system that is cost effective with a high level of performance and reliability. The system concept with performance data of key components will be presented.
    • 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.
    • 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.
    • 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.
    • 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)
    • 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.
    • 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.
    • Error Performance Bounds for M-Ary Digital FM with Predetection Sampling

      Cox, Timothy F.; Stanford University (International Foundation for Telemetering, 1987-10)
      Coherent detection of full response M-ary digital FM corrupted by additive white gaussian noise is studied. Prior to detection processing the signal plus noise is bandpass filtered and sampled. Upper error bounds which are applicable to the sampled system are given. With these bounds some comparisons of the effects of system parameter selection on the error performance can be made. These system parameters include deviation ratio, baseband pulse shape, sampling rate, number of levels (M), and signal-to-noise ratio.
    • 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.
    • 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.
    • High Data Rate Reed-Solomon Encoding and Decoding Using VLSI Technology

      Miller, Warner; Moakis, James; Goddard Space Flight Center (International Foundation for Telemetering, 1987-10)
      Presented as an implementation of a Reed-Solomon encoder and decoder, which is 16-symbol error correcting, each symbol is 8 bits. This Reed-Solomon (RS) code is an efficient error correcting code that the National Aeronautics and Space Administration (NASA) will use in future space communications missions. A Very Large Scale Integration (VLSI) implementation of the encoder and decoder accepts data rates up to 80 Mbps. A total of seven chips are needed for the decoder (four of the seven decoding chips are customized using 3Fm Complementary Metal Oxide Semiconduction (CMOS) technology) and one chip is required for the encoder. The decoder operates with the symbol clock being the system clock for the chip set. Approximately 1.65 billion Galois Field (GF) operations per second are achieved with the decoder chip set and 640 MOPS are achieved with the encoder chip.
    • An Implementation of Concatenated Coding Scheme on Indian Spacecraft

      Martin, Kamalini; Seshaiah, R.; Vasantha, E.; Rajangam, R. K.; ISRO Satellite Centre (International Foundation for Telemetering, 1987-10)
      A Concatenated Coding Scheme to provide an extremely 'clean' channel is suggested for onboard spacecraft telemetry system by the Consultative Committee for Space Data Systems (CCSDS). The outer code is a Reed Solomon block code and the inner, a Viterbi or Convolutional Code. The Gaussian channel are corrected by the inner code. However, the Viterbi decoder may introduce some burst errors. These are then corrected by the Reed Solomon decoder. The inner Viterbi code (K=7, rate 1/2) was developed and implemented for the first time in RSD2 (Rohini series) satellite. The outer code has not yet been implemented onboard spacecraft since the decoder has not been fully developed. However, the onboard encoding system (255,223) has been developed and tested. This paper describes the development and implementation of Viterbi encoder in RSD2 satellite along with its inorbit performance.
    • 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.