Turner, William C.; Electro Magnetic Processes, Inc. (International Foundation for Telemetering, 1984-10)
      An Over the Horizon Command/Data Link is fraught with unforeseen design problems. Multipath, ducting, holding aircraft position and altitude, as well as base-band signal processing equipment interface anomalies contribute to link degradation beyond predicted quality. This paper describes a three channel link, L-band, MDI-band, and S-band, over which command, video, and telemetry respectively are transmitted. Successful operation is currently achieved over a 100 mile range.

      Saulsberry, Garen J.; Reber, Tilo; New Mexico State University (International Foundation for Telemetering, 1984-10)
      The Physical Science Laboratory has developed a process for digitizing analog data using state-of-the-art equipment and software techniques. The problems encountered have been resolved using off-the-shelf computer equipment, a PSL interface unit, and systems application software to meet the specific needs of high-speed, analog data collection through digitization. The authors relate the problems encountered in collecting the raw data, processing it through the analog-to-digital converter and host computer, and recording the data on digital medium. The reader is taken through the design of a system to digitize analog data and log it on a high-speed computer disk system. The design is backed by actual test results showing the capabilities and limitations of the system. The paper illustrates the techniques used to collect the analog data through the system and the means used in the recovery process of the data in the post-collection period.

      Cox, T. F.; Nichols, M. H.; Naval Weapons Center (International Foundation for Telemetering, 1984-10)
      In order to comply with certain mission requirements, it is necessary to encode telemetry data into pulse code modulation (PCM). For this reason, test data have been obtained in order to determine the effects of quantization errors and bit errors with special reference to wide band noise-like data signals involving data reduction by spectral analysis. The use of notch noises tests for determining coder/decoder (CODEC) performance has been evaluated. Test procedures and test results are given using CODEC configurations of 4 to 12 bits per word. Parameters for encoding constant bandwidth (CBW) and proportional bandwidth (PBW) subcarrier multiplexes for PCM transmission are included.

      Winslow, Roger G.; Winslow Consultants (International Foundation for Telemetering, 1984-10)
      The increased United States dependency on space systems for military operations has resulted in the need for major upgrades in the survivability of our space systems in both the space and ground segments. Achievement of this survivability upgrade is in turn dependent on the exploitation of new technologies across a broad spectrum of disciplines. This paper will focus on the technologies which must be considered for enhancing the survivability of the space mission ground segment. Technologies to be discussed will include nuclear hardened mobile terminals, rapidly deployable multiple frequency antennas, ranging from S-Band to EHF, A-J communications, standardization, application of VHSIC and VLSIC, Artificial Intelligence, simulation and built-in test.

      Reinhard, Kenneth L.; Darlington, John C.; Ford Aerospace & Communications Corporation (International Foundation for Telemetering, 1984-10)
      Automated acquisition of a satellite’s downlink signal by the main beam of a ground station’s tracking antenna is complicated by the presence of antenna pattern sidelobes and potential large uncertainties in the spatial and/or frequency location of the signal. Sidelobe acquisition prevents autotracking and telemetry reception, and large uncertainties require time for coordinated antenna and receiver search. Use of an auxiliary antenna assists in resolving the sidelobe intercept problem, and a high speed digital receiver alleviates the problems associated with spatial and frequency uncertainty. The antenna and receiver, under processor control, constitute a fully automated system. The associated processor software controls the antenna motion during the search phase, selects the proper receiver configuration for the expected signal environment, makes the main beam versus sidelobe intercept decision and switches to autotrack mode upon successful signal acquisition.

      Wagner, Robert E.; Ford Aerospace & Communications Corporation (International Foundation for Telemetering, 1984-10)
      National defense strategies rely on force enhancement, space defense, space control and space force application functions being provided by survivable space resources. The ground command and control support for these functions must be at least equally survivable. An approach to meeting these ground survivability requirements is presented in this paper. A highly mobile satellite control system is presented incorporating recent technology advances into a modular design that satisfies a wide variety of user requirements in all levels of conflict. Ground/Air Transportability is enhanced significantly by the incorporation of monolithic phased arrays and miniaturized Tracking, telemetry and command (TT&C) equipment and data processing hardware. Hardness is enhanced by the incorporation of new materials and an advanced structural design that protects against EMP, blast thermal effects and terrorist activities. A preliminary design is described that indicates how modularity supports a spectrum of expected operating scenarios.

      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.

      Sheng Y. Peng; Pfaff, Gerald A.; Teledyne Micronetics (International Foundation for Telemetering, 1984-10)
      An electrically-small, lightweight, and low RCS (radar cross-section) Monopole Array Antenna has been developed for wide band application. The monopoles were printed on a low dielectric constant (εr = 2.3) substrate and fed by a modified meanderline microstrip feed structure, with quarter-wavelength stubs to improve feed efficiency. The operational frequency is from 0.65 to 2.0 GHz. The physical size of the monopole array measures only 0.125 wavelength in height. The weight is about 0.3 pounds. A four-element subarray was built and tested. Its overall physical size is 2.5 inches in height by 10 inches in length by 24.4 inches in width. The measured gain and pattern data are presented, as well as the low RCS property and many applications of the monopole array.

      Hellwig, Helmut; Levine, Martin W.; Frequency and Time Systems, Inc. (FTS) (International Foundation for Telemetering, 1984-10)
      The commitment of the Global Positioning System (GPS) to use atomic clocks dates back more than ten years ago when the first major contractual commitment was made with the award of the first space vehicle procurement contract to Rockwell International in 1973. The primary purpose of atomic clocks was, and still is, to provide autonomy of time and frequency to the individual spacecraft. The objective of the atomic clock was, and still is, the assurance of time accuracy to the nanosecond level. This implies a positioning accuracy of the order of feet. We note that timing accuracy and positioning accuracy are related via the speed of light; thus, 1 ns time accuracy translates to 1 foot positioning accuracy. The role of the atomic clock is to preserve this accuracy autonomously out to many days in case uploading should be impossible or undesirable. Thus, because 10 ns per day equals 10¯¹³ fractional frequency stability and 10 ns per week represents parts in 10¹⁴, atomic clock stabilities of 10¯¹³ and better for periods of days are needed for GPS. Because of the state-of-the-art prevalent in the early seventies, rubidium devices were chosen for the first GPS satellites (Navstar 1 thru Navstar 4). At the same time, FTS went under contract to develop a space-qualified cesium device. Navstar 5 thru Navstar 12 will carry a complement of three rubidium and one cesium clock. Starting with Navstar 13, the Block II GPS Satellite Time/Frequency Subsystem will consist of two rubidium and two cesium clocks. The rubidium devices are produced by the Autonetics Division of Rockwell International using an Efratom physics package. The cesium clocks are produced by Frequency and Time Systems, Inc. The need for a total of four clocks per satellite results from the systems planner’s risk assessment focussing on the assurance of in excess of 7 1/2 years of “in-spec” life for this basic subsystem of the Navstar satellite.

      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.

      Pasek, G. E.; Lockheed Missiles and Space Corporation (International Foundation for Telemetering, 1984-10)
      The paper will summarize the approach and considerations being given to the development of a survivable Mission Control Segment. Satellites of the future need to be designed with control needs in mind and provided with a high degree of autonomy and intelligence. Earth based support must be designed around operators who are limited in skill and therefore rely on sophisticated software and a degree of Artificial Intelligence. The total system approach, progress, and findings for these future Space and Ground Systems will be presented during the 20+ minute overview discussion.

      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).

      Moses, J.; Sklar, R.; Hughes Aircraft Company (International Foundation for Telemetering, 1984-10)
      The Digital Voice Network project is a 1984 IR&D program within the Microelectronic Systems Division of the Hughes Aircraft Company. The project is intended to advance the state-of-the-art in digital voice technology and demonstrate digital voice transmission using advanced microprocessor technology and token passing bus network architecture. This paper discusses the Digital Voice Network design architecture, voice terminal design and implementation, and finally future plans to satisfy digital voice requirements in a military environment.

      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.

      Holeman, Dennis L.; Blackwell, Earl G.; SRI International (International Foundation for Telemetering, 1984-10)
      This paper describes equipment to be developed by the GPS Range Applications Joint Program Office (RAJPO) for use on test and training ranges. The equipment is to be modular; the various modules may be assembled in range-specific configurations by the individual range development organizations to perform measurement and communications functions.

      Anderson, Robert B.; Industrial Data Link (International Foundation for Telemetering, 1984-10)
      Industrial Data Link Corporation is presently installing a 3 phase, 30 Km fiber optic voice/data communication system for the Yuma Proving Ground (YPG) in Arizona. This system will provide a backbone communication system for YPG to transmit digital telemetry data and voice circuits between 3 test centers and the Base Dial Central Office. The fiber optic cable is being installed in three different modes; underground (direct burial), duct and aerial. Our proposed paper would cover the following areas: a.) System requirements --data channels (up to 56 Kb/s) --voice channels --future growth (video) b.) System design - component description c.) Installation d.) Test and initial system operation e.) Pictures (slides) and video coverage of system installation to augment the presentation f.) Cost and technical trade-off studies between fiber optic cable and microwave link as the communication medium g.) Cost analysis (ratios) for laying of fiber optic cable, dollars per meter for burial, duct and aerial h.) Summary of state-of-the-art of fiber optic component and predictions of future component/system capabilities for range telemetry applications. i.) The special characteristics of fiber optic cable links as applied to secure telemetry requirements on Government Test Ranges.
    • An Integrated Approach to Telemetry Ground Stations Using Distributed Processing

      Thompson, William B., Jr.; Loral Instrumentation (International Foundation for Telemetering, 1984-10)
      Telemetry data processing ground stations commonly unite dissimilar equipment into what is often a large disjoint series of synchronizers, specialized front end processors, and high performance back end data processors. With a few basic building blacks, small-tolarge uniform systems are being built that avoid this problem while hiding the task size from the end user yet allowing flexibility in the data acquisition and processing. This discussion focuses on the implementation of an integrated telemetry processing system with varying levels of complexity. The discussion covers the full spectrum from the simple processing element (single pc board) to the data processing substation (single instrument) to a full load sharing, redundant, distributed system (network of substations). Each level utilizes a different form of distributed processing yet adheres to an overall philosophy of date flow as opposed to fixed instruction sequencing.

      Barbour, Susan; Figgie International Inc. (International Foundation for Telemetering, 1984-10)
      In a phase-locked PM demodulator, the input signal is modulated by a periodic waveform, particularly when the loop bandwidth is less than the sideband to carrier spacing, and thus discrete sidebands are apt to appear about the carrier frequency. This frequently results in a sideband locking instead of phase-locking to a selected carrier and aided-acquisition is then required. Conventional techniques such as discriminator-aided-acquisition have been implemented by Mostrom¹ and Victor et al.² to correct this problem, however, this approach necessitates a large carrier to noise ratio (CNR) in the bandwidth of the discriminator. The current study describes a novel approach to extend the threshold for a phase-locked loop designed for Hartman Systems’ telemetry receiver. By phase remodulating the error signal, the network reduces the phase swing of the signal and restores the carrier power so as to provide anti-sideband properties for biphase and PM modulation up to 1.3 radians deviation at all modulation frequencies and at a signal level where CNR is greater than 5 dB above PM threshold.

      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.

      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.