• 20-WATT X-BAND SOLID-STATE TWTA REPLACEMENT

      Postal, R. B.; Boreham, J. F.; Conroy, B. L.; Jet Propulsion Laboratory, California Institute of Technology (International Foundation for Telemetering, 1984-10)
      In the past, traveling wave tubes have dominated the power amplifier field in space flight transmitter applications. TWTAs however, are expensive, and high-power TWTAs may be relatively unreliable when considering end-of-mission operating requirements of up to 10 years and longer. Recent improvements in reliable solid-state designs including Gallium Arsenide FETs have resulted in efficient X-band devices which operate at multi-watt levels. A number of these devices would be combined in parallel to achieve the power output desired. This paper discusses the development of an efficient 20 watt X-band solid-state power amplifier to be used as a TWTA replacement for space flight applications. The 20-watt assembly shown in Figure 1 consists of two stand-alone, 8-channel, 11-watt assemblies operating in parallel through a 2-way switched power combiner. Particular emphasis is placed on the power amplifiers and a one-step, 8-way power divider/combiner pair. Each power amplifier channel has 3 stages of gain and develops 1.6 watts of RF output with 18 dB of compressed gain. A driver amplifier module provides additional system gain and a 0.5-watt drive level for the high power sections. The GaAs FET devices utilized are from the output of a device improvement program which has a goal of a minimum power added efficiency of 40%. The one-step combiner utilizes a novel technique to achieve a combining efficiency of 90%. The full system, including the DC-DC power converter, yields an overall system efficiency of 25%. A thermal sensor in the power conditioner is used to hold amplitude variations to ±0.3 dB from 0 to 50°C and phase variations to ±10° over the same range. The assembly also operates in a low power mode producing 9 watts of RF when only one 11-watt assembly is powered and the switched combiner open circuits the off channel.
    • AIR FORCE FLIGHT TEST INSTRUMENTATION SYSTEM

      Lamy, Michael F.; SCI Systems, Inc. (International Foundation for Telemetering, 1984-10)
      In January, 1983 SCI Systems, Inc. initiated design under a contract with the U.S. Air Force for the development of the Air Force Flight Test Instrumentation System (AFFTIS). This system is being developed to provide for the flight test instrumentation needs of the Air Force through the 1990s. The requirements specification was derived from the results of a survey conducted by the Air Force approximately two (2) years prior to contract award. The results of this survey were that the new system should provide more channels and higher frequencies, all in smaller size. In addition, the system should be modular and easily expandable to accommodate testing of yet undefined future aircraft systems. This paper describes the AFFTIS System as it is presently designed and some of the unique concepts used to meet the specified design goals.
    • AIR FORCE SATELLITE CONTROL FACILITY ARCHITECTURE

      Konopasek, L. K.; The Aerospace Corporation (International Foundation for Telemetering, 1984-10)
      This paper presents an architectural overview of the Air Force Satellite Control Facility (AFSCF) with emphasis on the network’s Remote Tracking Stations (RTSs). The AFSCF originated twenty-five years ago, and has evolved into a global satellite service network. This worldwide network is composed of twelve RTSs, located at seven geographically dispersed locations, and a Satellite Test Center (STC) at Sunnyvale, California. The AFSCF provides real-time telemetry, tracking, and commanding (TT&C) service to Department of Defense (DoD) spacecraft and launch vehicles. In response to changing DoD space support requirements, the AFSCF and its RTSs have grown through expansion and modernization of their tracking, data processing, and communication capabilities. What follows is, then, a review of this network evolution; a description of today’s, stations, their capabilities and limitations; an introduction of planned improvements; and a view of what will be required for satellite service in the future.
    • AIRBORNE TELEMETRY: THE ADVANCED RANGE INSTRUMENTATION AIRCRAFT

      Avery, Lawrence G., Jr.; ARIA Programs Division (International Foundation for Telemetering, 1984-10)
      The topic of this paper is the history of ARIA from its beginning during the Apollo program to its current use as an airborne telemetry platform for orbital, ballistic, and cruise missile testing. The evolution of ARIA telemetry equipment from 1968 to the present will be discussed, as well as plans for future modernization and improved capability. Specific areas to he covered include: real-time data relay, pseudomonopulse tracking, onboard data processing, computer controlled tracking, new receivers, new recorders, and planned modifications to meet future requirements.
    • ANALYTICAL STUDY ON BIT-SYNCHRONIZATION PROBLEMS IN A CODED COMMUNICATION SYSTEM

      Ng, Wai-Hung; The Aerospace Corporation (International Foundation for Telemetering, 1984-10)
      Many bit-synchronization techniques in digital communications depend on bit transitions for successful operation. In this paper, we first categorize the four main sources of generating transitionless signals. Then we describe general properties of channel coding and explain that, by injecting a well-selected detectable error pattern into the transmitted and coded signal, this bit transitionless problem can be eliminated without any additional bandwidth penalty. Finally, examples in both block code and convolutional code are selected for illustrating this simple but useful application.
    • APPLYING TELEMETRY THEORY TO THE REAL-WORLD

      LAW, EUGENE L.; Pacific Missile Test Center (International Foundation for Telemetering, 1984-10)
    • ARTS OVERVIEW

      Skinner, Patrick J.; Ford Aerospace & Communications Corporation (International Foundation for Telemetering, 1984-10)
      Modernizing labor intensive Remote Tracking Station (RTS), increasing individual station capacity, and providing interoperable links between three separate Air Force satellite networks are the objectives of the Automated RTS (ARTS) program. (Viewgraph #1, Title/Logo)
    • ASPECTS OF OPERATOR INTERFACE DESIGN FOR AN AUTOMATIC TRACKING ANTENNA CONTROLLER

      DeBrunner, Keith E.; Dyn-Opus, Inc. (International Foundation for Telemetering, 1984-10)
      The processing power afforded by embedded microcomputers in state-of-the-art control applications offers the design engineer greatly expanded opportunities for improved ergonomic design, even without the use of “soft” actuator and/or display devices (which are sometimes undesirable and/or unacceptable). Especially important is the exploitation of software to simplify the hardware design while simultaneously implementing decision/mode logic that would be prohibitively expensive if done in hardware alone. The designer is often confronted with an ocean of possibilisties, and must make intelligent decisions in order to satisfy increasingly demanding applications and sophisticated users. The design decisions and resulting features and behaviors of an automatic antenna control unit are discussed from the operators point of view (black box), but also with the intention to detail some of the logic necessary to implement these features. This is prefaced by a discussion of the characteristics of the primary operator interface, the front panel, and the factors that influenced its design. Areas for future improvement of the design are also mentioned.
    • ASSESSMENT OF METROLOGICAL PARAMETERS BY MEANS OF FIBER-OPTIC SENSORS

      Kist, Rainer; Fraunhofer-Institut für Physikalische Messtechnik (International Foundation for Telemetering, 1984-10)
      Fiber-optic sensors will get their share of the sensor market only if they can be made available at low prices or if they can solve metrological problems that have no suitable solutions within conventional sensor techniques. Since fiber-optic components are in general still high cost items, fiber-optic sensors are not likely to become competitive in this respect within the near future. These sensors do provide, however, important specific advantages such as isolation against high voltage, immunity against electromagnetic fields as well as explosive and/or corrosive environments, possibility of miniaturized and compact packaging of the sensing element, and application within a broad temperature range. Multimode fiber-optic sensors for parameters such as temperature, pressure, level , and refractive index are on the market already or very close to being commercialized. Monomode fiber-optic sensors are not yet on the market due to their more demanding technology and the corresponding higher cost level . They are expected, however to provide at acceptable costs in a forseeable future high precision solutions for metrological tasks under specific conditions (e.g. Sagnac gyroscopes, hydrophones, temperature measurement in a microwave field).
    • BALLISTIC RAIL GUN – SOFT RECOVERY TECHNIQUE

      Paduano, Michael J.; Zimmerman, John R.; HQ US Army Armament Research and Development Center (International Foundation for Telemetering, 1984-10)
      The ARDC 155mm Ballistic Rail Gun Test Facility permits the soft recovery of a test projectile and its payload after subjection to an actual gun launch environment. High G hardening and testing of various electronic and mechanical components can be conducted by use of this system. This paper will discuss the conception, operation and reliability of the Ballistic Rail Gun, and the advantages and limitations of its use in qualification of components. Also discussed will be the development of a novel radar technique to determine muzzle velocity for Rail Gun tests, and a separate telemetry system for characterizing in-bore (acceleration) and in-rail (deceleration) environments.
    • BENEFITS OF POLARIZATION DIVERSITY RECEPTION

      Berns, K. L. (Ken); SETAC Inc. (International Foundation for Telemetering, 1984-10)
      The utilization of polarization diversity reception to compensate for pattern irregularities of telemetry transmitting antenna systems is examined. Statistical analyses are conducted to compare signal strengths of the orthogonal polarization components of transmitted radio waves. Probability density functions and cumulative distribution functions of transmitting antenna gain patterns are calculated. These statistical functions are used as the basis for comparisons of the quality of recovered signals with and without polarization diversity capabilities at the receiving station. It is concluded that polarization diversity can be used to significantly improve signal quality in the presence of antenna pattern irregularities.
    • BENEFITS OF USING A PROGRAMMABLE ARCHITECTURE MULTIPROCESSOR IN A REAL TIME TELEMETRY SYSTEM

      Lewis, Malcolm L; ACROAMATICS, Inc. (International Foundation for Telemetering, 1984-10)
      Designing and constructing a real time telemetry system for unique applications can involve considerable time to evaluate, choose, acquire, and interface the necessary elements. The use of a highly versatile single chassis telemetry acquisition system can reduce or obviate the need for external pre- or post-processors as well as the potentially difficult hardware and software interfacing. It also results in an easily upgradable and generally modifiable system from the development phase, through delivery, and on site by both the designer and user. The basis of the system described here is a parallel/serial multiprocessor whose architecture is programmable.
    • A BROADBAND DIGITAL GEOPHYSICAL TELEMETRY SYSTEM

      Seeley, Robert L.; Daniels, Jeffrey J.; U.S. Geological Survey (International Foundation for Telemetering, 1984-10)
      A system has been developed to simultaneously sample and transmit digital data from five remote geophysical data receiver stations to a control station that processes, displays, and stores the data. A microprocessor in each remote station receives commands from the control station over a single telemetry channel. The commands adjust the sensing amplifier’s input voltage range (1 microvolt to 2 volts peak-to-peak), the number of samples (128 to 30,000), the sampling rate (256 to 32,768 samples/sec), and the number of signals (1 to 16) to average at the remote stations. A 12 bit analog-to-digital converter samples data with bandwidths of 100 Hz to 10 kHz for time periods selected from 100 seconds to 1 second, respectively. Each remote station begins sampling geophysical signals when it receives a synchronizing pulse relayed from the control station. Digitized geophysical data is transmitted to the control station over broadband (100 kHz bandwidth) UHF telemetry channels using standard asynchronous serial (19.2 kbaud) techniques and hardware dropout detection and recovery. The amount of data (480 kbits) and the maximum time to transmit data (30 secs) dictate using broadband telemetry (even though most geophysical telemetry is less than 10kHz in bandwidth). Header information (transmitted before the data) contains station number, digital sampling parameters, transmission block size, and checksum. This information is used by a computer program (in a PDP-11/23 (***) minicomputer) to maintain up to 5 simultaneous Direct Memory Access (DMA) transfers from the remote stations into 5 separate data buffers. Filled buffers are transfered (via an IEEE-488 bus) to an interactive analysis and display system (HP9845C (***)) for selecting data to be stored on magnetic media for subsequent laboratory analysis.
    • CALCULATING RMS VALUES FROM DIGITAL AND SAMPLED DATA

      Rieger, James L.; Birch, Kent N.; PE/PTBW; Naval Weapons Center (International Foundation for Telemetering, 1984-10)
      The root-mean-square (RMS) of the amplitude of a waveform is defined for continuous data. When sampled data is used, the signal may be converted to a continuous analog signal, filtered, and the RMS value measured by traditional means; if, however, the data exists already in sampled digital form, the RMS value can be calculated on the sampled data itself. By so doing, moreover, the lower integration limit and the integration interval can be varied to provide better frequency response and/or accuracy. A computer program in BASIC is shown for demonstration purposes which may be spliced into a larger data analysis program.
    • CANADIAN FORCES PCM TELEMETRY PROCESSING AND DISPLAY SYSTEM

      Glenesk, Major L.B.; Marriott, Captain J.L.; Aerospace Engineering Test Establishment, CFB Cold Lake (International Foundation for Telemetering, 1984-10)
      Canadian Forces (CF) flight test facilities were recently updated to support testing of the CF-18 aircraft by the development of a new ground based PCM telemetry processing and display system (TPADS). Additional enhancements to this system are currently underway, or being considered, to further improve flight test mission control and data processing functions and produce a system capable of meeting CF flight test requirements into the 1990’s.
    • COMMAND AND TELEMETRY IN AUTONOMOUS SPACECRAFT DESIGN

      Turner, Philip R.; Jet Propulsion Laboratory, California Institute of Technology (International Foundation for Telemetering, 1984-10)
      Spacecraft autonomy is provided by placing control authority for functional operations on board the spacecraft. A three-step control process utilizes sensed information to determine and initiate appropriate control actions. A critical design feature is the selection of appropriate sensory data and the means by which it is passed to the onboard control resource. This paper summarizes some major steps in the evolution of autonomous design features for planetary exploration spacecraft.
    • COMMAND, CONTROL AND COMMUNICATIONS (C³) FOR THE DEFENSE METEOROLOGICAL SATELLITE PROGRAM

      Williams, Stephen L., Captain; Kinney, Thomas W.; USAF Space Division; Harris Government Information Systems Division (International Foundation for Telemetering, 1984-10)
      This paper describes the architectural philosophy and the interaction between the DMSP C³ ground system and the strategic and tactical users of DMSP imagery data. Some of the ongoing activities relating to future enhancements and survivability are also explored. At the present time, the ground systems Satellite Operations Center (SOC) has been installed at Offutt Air Force Base, Nebraska, and is supported by the two remote Command Readout Stations (CRS’s) at Fairchild Air Force Base, Washington, and Loring Air Force Base, Maine. All commanding, planning and telemetry processing is centralized at the SOC. Backup and redundant subsystems and communications services are provided for reliable operation plus there is an internet with the Air Force Satellite Control Facility (AFSCF) for early orbit and anomaly support.
    • COMPANDER CIRCUITS IMPROVE TRANSDUCER DATA QUALITY

      Rieger, James L.; Naval Weapons Center (International Foundation for Telemetering, 1984-10)
      AC-coupled transducers such as crystal accelerometers and microphones can produce a large dynamic range of signals, but the expected level from such devices in an actual test situation may be difficult to predict. Use of compander circuits intended for telephone and “hi-fi” systems can increase dynamic range and accuracy of the signals from such devices and reduce noise at low levels and clipping at the top of the range. Companders (COMPressor plus expANDER) can be used in single- or double-ended modes depending on the data requirements. They do introduce predictable artifacts of their own, but many of these can be removed.
    • COMPUTER ANALYSIS OF THE OXFORD CONTINUOUS BLOOD PRESSURE MONITORING: DATA PROCESSING SYSTEM

      Di Marco, A.; Cordone, L.; Palatini, P.; Mormino, P.; Pessina, A.C.; Sperti, G.; Dal Palú, C.; University of Padova (International Foundation for Telemetering, 1984-10)
      Blood pressure signals recorded continuously in ambulatory patients using the Oxford system were analyzed by an IBM 370 computer in order to obtain beat by beat systolic and diastolic blood pressure along 24 hour blood pressure recordings. The method of digitizing the signal and the analysis of the sphygmogram are presented and discussed. Synthesis of the several thousands data obtained in 24 hour recordings and plotting of the data for clinical purposes and pharmacological studies are also reported.
    • A COMPUTERIZED CHECK-OUT SYSTEM FOR TRANSDUCERS IN NUCLEAR POWER PLANTS

      Brandt, Axel; SCS Technische Automation und Systeme GmbH (International Foundation for Telemetering, 1984-10)
      A computerized check-out system for recording and analysis of test data of transducers in nuclear power plants is described. The system is composed of two subsystems, the STATIONARY and the MOBILE SYSTEM. The STATIONARY SYSTEM fulfills all necessary administrative functions, allows data analysis, reporting, and longterm storage of test data. The MOBILE SYSTEM is the test device. It is set up by three components - controller unit, interface, and microcomputer - the whole being assembled on a moveable wagon which makes on site testing of the transducers possible. The number of MOBILE SYSTEMS is selectable according to user needs and environmental condititions. Data transport between the systems is accomplished via magnetic tape cartridges or online by a standardized communication line.