• A Band-Width Limiting Circuit Improves Telemetry System Operation

      Lillie, Derek S.; LORAL CONIC (International Foundation for Telemetering, 1990-11)
      Present bandwidth limiters use a six-pole bessel filter approach to limit the power bandwidth of the transmitter to IRIG-106-86 requirements. However, the filter must be reconfigured if frequency changes in the data stream are desired for system requirement purposes, eg. adding encryption. The circuits set forth herein will provide for frequency change of the data stream while also providing a power increase by reducing the out of band power.
    • Chinese Development on Aero-space Telemetry Ground Station

      Chang-jie, Shi; The Ministry of Aero-space Industry P.R.C. (International Foundation for Telemetering, 1990-11)
      This paper introduces the systematic design features of development of Chinese aero-space telemetry ground station from the following seven respects: 1. The fundamental factors to promote the 1980s’ development of telemetry ground station. 2. Increasing the flexibility of telemetry ground station. 3. The approach of one-time system design and multisteps development. 4. Decreasing the effect and influence of host computer. 5. Increasing the efficiency of buses. 6. To pay attention to magnetic recorder. 7. According to realistic utility to determine the configuration and specification of telemetry ground station.
    • Color Extension for the HORACE TV Compression Protocol

      Gattis, Sherri L.; Rieger, James L.; Naval Weapons Center, China Lake, California (International Foundation for Telemetering, 1990-11)
      The HORACE protocol[5] was designed as a common medium of exchange for digitized black-and-white television images at varying resolutions at bit rates from below 9600 to over 50M bits per second. At the 1 time of the protocol’s creation, “hooks” were added to allow use of the system to transmit and receive two-and three-color images from an NTSC, RGBY, RGB, or “S-type” input and produce outputs in the same format, but those systems remained undefined. Two systems implementing various features of the extended color protocol have been built and demonstrated by two different manufacturers, and an effort to standardize the protocol for all users and manufacturers is underway.

      Deutermann, Alan; Schaphorst, Richard; Delta Information Systems, Inc. (International Foundation for Telemetering, 1990-11)
      As the role of television in the aerospace industry has expanded so has the need for video telemetry. In most cases it is important that the video signal be encrypted due to the sensitive nature of the data. Since this means that the signal must be transmitted in digital form, video compression technology must be employed to minimize the transmitted bit rate while maintaining the picture quality at an acceptable level. The basic compression technique which has been employed recently, with successful results, is a combination of Differential PCM and Variable Length coding (DPCM/VLC). This technique has been proposed to the Range Commanders Council to become a possible standard. The purpose of this paper is to compare the basic DPCM/VLC technique with alternative coding technologies. Alternative compression techniques which will be reviewed include Transform coding, Vector Quantization, and Bit Plane coding. All candidate techniques will be viewed as containing four elements -- signal conditioning, signal processing, quantization, and variable length coding. All four techniques will be evaluated and compared from the stand point of compression ratio and picture quality.

      Law, Eugene L.; Pacific Missile Test Center (International Foundation for Telemetering, 1990-11)
      This paper will describe the Pacific Missile Test Center’s (PMTC) approach to a computer controlled telemetry receive and record system. The advantages of this system include: fast, accurate equipment setup and interconnection, automatic verification of operational status, and simplified signal monitoring. PMTC personnel developed the system architecture and software. The system hardware is all unmodified off-the-shelf equipment. The main design drivers were cost, reliability, and minimizing the effect of any single point failure. The system uses many individual switches instead of a small number of large switch matrices. Manual patching capability has been maintained. This patching system provides a backup solution if all the computers get “zapped”. The patching system also provides increased signal routing flexibility.

      Hart, Michael James; White Sands Missile Range (International Foundation for Telemetering, 1990-11)
      The seven WSMR Transportable Telemetry Acquisition Systems (TTAS), have served WSMR well as primary telemetry tracking systems since their acquisition over twenty years ago. Increasing maintenance demands for the original analog position control system (the antenna feed, servo power amplifiers, and position compensation) coupled with the potential for substantial tracking system performance improvement and self-diagnostic capability offered by current technology led to the establishment of a new instrumentation development task at WSMR whose objective was the development of a new, almost totally digital prototype tracking system to replace the aging analog control system in one of the TTAS’s. A modern conical scan feed has replaced the original monopulse feed, pulse-width-modulated power amplifiers have replaced the originals using SCR’s, and a VMEbus-based computer using a real-time operating system has replaced the analog compensation and overall control of the system. In this paper, following an overview of the prototype tracking system, the results of the development of a new position control algorithm for the prototype tracking system are described using root loci, computer simulation, and from the actual tracking system using servo test software developed for the computer controller. The results of the study of the old analog control system using computer simulation are presented for comparison. Problems encountered with the TTAS directly affecting position control are also presented. The new position control algorithm was designed to accommodate all of the critical tracking system nonlinearities (power amplifier saturation, current limiting, dead band, and control output saturation), all tracking modes (autotrack, manual, and using external pointing data), different operating bandwidths, and all possible drive inputs to the system. It has converted the tracking system from a type-1 to a type-2 control system improving the dynamic capability of the TTAs.

      Law, Eugene L.; Pacific Missile Test Center (International Foundation for Telemetering, 1990-11)
      This paper will present the results of a study to correlate tape dropouts and data quality. A tape dropout is defined in the Telemetry Standards as “a reproduced signal of abnormally 1 low amplitude caused by tape imperfections severe enough to produce a data error” Bit errors were chosen as the measure of data quality. Signals were recorded on several tracks of a wideband analog instrumentation magnetic tape recorder. The tape tracks were 50 mils wide. The signal characteristics were analyzed when bit errors or low reproduce amplitudes were detected.

      Coonce, Kenneth G.; Schumacher, Gary A.; Loral Data Systems (International Foundation for Telemetering, 1990-11)
      This paper describes the overall system design and performance characteristics of a complete telemetry system for a new flight test center which Loral Data Systems is currently under contract to provide to a European government. The system encompasses subsystems for airborne data acquisition and flight line check-out, a mobile ground telemetry system, and a fixed facility. The fixed facility includes a ground telemetry system for real time data processing and test control, and a data processing system for postflight analysis. The system represents a fully integrated approach to flight test systems which addresses the end-to-end requirements from airborne data acquisition and real time flight monitoring through aircraft performance and stability/control analysis. The architecture of the ground systems illustrates how preprocessing can be utilized to create powerful real time telemetry systems even with modest general purpose computer capability.

      Robillard, Jean-Claude; Brimbal, Michel; Gould Inc., Array Recorders Division; Gould Inc., Recording Systems Division (International Foundation for Telemetering, 1990-11)
      In the past 2 to 3 years, linear array recorders based on direct thermal printing technology have proven to be the recorders of choice for a large number of telemetry display stations. This technology initially developed for facsimile communications has evolved to meet speed and reliability required by the operation of recorders in the telemetry station environment. This paper discusses the performance of various direct thermal printing techniques employed. The focus is given to parameters that are critical to telemetry station operation such as quality of the chart output, maintenance and support, reliability and cost. The reliability issue is discussed at length as it is impacted by printhead thermal stress and mechanical wear. Other printing technologies available for chart recording are briefly reviewed as they may appear to be suitable alternatives in some telemetry applications.
    • Digital Signal Processing Techniques Used to Demodulate Multiple Types of Telemetry Data

      Ziegler, Frank A.; Microdyne Corporation (International Foundation for Telemetering, 1990-11)
      Telemetry systems today are required to receive a variety of modulation formats. Typically, to change the format required changing the demodulator unit or large switching systems. Using some common digital building blocks and multiplexers, the user can change demodulation mode by pressing a button. This paper describes a system that demodulates PM, FM, BPSK, QPSK and DSB AM.

      Cipolla, Frank; Seck, Gerry; Datron Systems Inc. (International Foundation for Telemetering, 1990-11)
      Datron Systems has designed a dual band EHF autotrack feed. The feed allows simultaneous reception and autotracking at K band while transmitting at Q band. The feed design and operation is discussed.

      Walsh, Edmond; S.T. Research Corporation (International Foundation for Telemetering, 1990-11)
      Small telemetry antennas (under ten feet) are popular on many ranges due to ease of handling and low cost. Unfortunately spillover, taper loss, diffraction loss, aperture blockage and feed efficiency can combine to reduce overall antenna efficiencies under ten percent. Even for a low cost antenna system, these are unacceptable losses. This paper characterizes these losses and introduces an efficient feed with a scanning acquisition beam specifically for small reflectors.

      Chavez, Tomas; Sutherland, Susan C.; White Sands Missile Range; Loral Data Systems (EMR) (International Foundation for Telemetering, 1990-11)
      The recently delivered Telemetry Data Handling System (TDHS) was designed to support the current and future needs of a multi-purpose realtime range system at White Sands Missile Range. The system provides for data acquisition, processing, and archival of PCM, PAM, and FM data. The addition of support for MIL-STD 1553 data input as presented in the SRAM II data format is currently in process by Loral Data Systems. The SRAM II format includes MIL-STD 1553 messages embedded in a traditional PCM mutiplex. These embedded 1553 messages must be extracted and processed in addition to standard processing of the PCM data. This paper discusses a general purpose solution to the handling of embedded 1553 data including: " Configuring the system components " Extracting the embedded messages " Processing the MIL-STD 1553 data " Testing the system

      James, Calvin L.; Bendix Field Engineering Corporation (International Foundation for Telemetering, 1990-11)
      Although prefiltering prevents the aliasing phenomenon with discrete signal processing, degradation in bit error performance results even when the prefilter implementation is ideal. Degradation occurs when decisions are based on statistics derived from correlated samples, processed by a sample mean estimator. i.e., a discrete linear filter. However, an orthonormal transformation can be employed to eliminate prefiltered sample statistical dependencies, thus permitting the sample mean estimator to provide near optimum performance. This paper will present mathematical justification for elements which adversely affect the bit synchronizer’s decision process and suggest an orthonormal transform alternative. The suggested transform can be implemented in most digital bit synchronizer designs with the addition of a Read Only Memory (ROM).
    • Enhancing the Capabilities of Digital Bit Synchronizers

      Windingland, Kim; Loral Instrumentation (International Foundation for Telemetering, 1990-11)
      Bit synchronizers have traditionally provided very little feedback to the user. This paper describes features that give the user a window into the quality of the signal and verification that the bit synchronizer is performing properly. In addition, this paper describes a feature that automates some of the bit synchronizer’s functions to maximize its performance. The features described are: (1) a Built-in Oscilloscope (BIO) to provide the user with a visual representation of the input signal; (2) a Link Quality Analyzer (LQA) to provide the user with a quantitative measure of the input signal’s quality (signal-to-noise ratio (SNR) measurement); (3) a Built-in Test (BIT) to provide confidence in the unit’s functional and bit error performance; and (4) an Automatic Adaptive Control (AAC) to maximize acquisition and bit error rate performance.
    • The Error-Correcting Codes of The m-Sequence

      Tingxian, Zhou; LIKUN, HOU; BINGXING, XU; Harbin Institute of Technology (International Foundation for Telemetering, 1990-11)
      The paper analyses the properties of m-sequence error-correcting codes when adapting the correlation detection decoding method, deduces the error-tolerant number formula of binary sequence with a good auto-correlation property being used as error-correcting codes, provides with a method to increase the efficiency of the m-sequence error-correcting codes and make its coding and decoding procedures in the form of framed figures.

      Saulsberry, Garen; New Mexico State University (International Foundation for Telemetering, 1990-11)
      Data continue to be produced in ever increasing rates and quantity. More transducers and instruments are being required, while those already installed are operated at higher rates to measure and verify the conditions within test environments. Increasing awareness of data security and of requirements for protecting those data once produced is an additional constraint on the test environment. Raw and processed data must be transported at higher rates to satisfy the requirements of today’s data acquisition and analysis systems. Any solution proposed must meet several tests to be considered as meeting the data transfer requirements for a data link system.

      Nimrod, Daniel W.; U. S. Army Aviation Technical Test Center (International Foundation for Telemetering, 1990-11)
      This paper briefly reviews past techniques for measuring FM deviation and discusses the limitations of past technology. Graphs of the Bessel functions are presented in terms of decibels (dB), offering a better method of measurement when used with a modern spectrum analyzer.
    • Frame Synchronization At 300 Mbps And Beyond ...

      Wunderlich, Kristin; Chesney, Jim; Bennett, Toby; Goddard Space Flight Center; Ford Aerospace Corporation (International Foundation for Telemetering, 1990-11)
      While most current ground based space telemetry acquisition systems are designed for and support data rates up to a few megabits per second (Mbps), NASA’s Tracking and Data Relay Satellite System (TDRSS) can support downlink rates up to 300 Mbps. In addition, the Advanced TDRSS (ATDRSS) is expected to support rates up to 650 Mbps. These high data rates will be required to support NASA’s future large scale operational programs such as the Space Station Freedom and the Earth Observation System. At the Goddard Space Flight Center, a prototype Frame Synchronizer card is under development which will operate at a minimum of 300 Mbps while providing a full suite of programmable functions such as 32 bit correlation, search-check-lock strategy, bit slip tolerance, fly wheeling, etc. In addition, cumulative quality data generation, on-board self diagnostics, and status/control processing are all integrated in this single card design. This level of functionality and very high data rate is made possible by the design of NASA application specific Gallium Arsenide (GaAs) Very Large Scale Integrated (VLSI) circuits to support space telemetry data system standards specified by the Consultative Committee for Space Data Systems. This paper will describe functions performed by this card and its supporting VLSI components.

      Wechel, Robert Van; Interstate Electronics Corporation (International Foundation for Telemetering, 1990-11)
      The GPS equipment developed in the tri-service GPS range applications program is now available for use. One promising application on test and training ranges is for pointing control of theodolites, laser trackers, and threat emitters. Theodolites and laser trackers are capable of extremely high accuracy in range applications, but suffer from a very narrow acquisition range, thus requiring external acquisition aiding. Unmanned threat emitters are also used that require external pointing information. In this application of GPS, a GPS receiver or translator is used on the test or training vehicle, and the position of the vehicle is downlinked to the tracking site. A pointing angle is then computed at the tracking site and is used to point or steer the theodolite, laser tracker, or threat emitter. Because of the high accuracy, of differential GPS, this method is very precise. Also, with a direct high-rate datalink, time delays for the pointing information can be very low, again providing very accurate pointing for high-dynamic vehicles. This method promises to be a highly cost-effective approach for steering these devices because it eliminates the requirement for continuous manning of the sites.