• A 16 WATT Ku BAND GaAs FET POWER AMPLIFIER

      Huang, Thomas K.; Rhodes, Richard A.; Mehta, Jayanti; Hughes Aircraft Co. (International Foundation for Telemetering, 1981-10)
      An experimental power amplifier using GaAs FETs was built and tested. This power amplifier delivered 16 watts of RF output power in mid Ku-Band. It employed 88 GaAs FET devices and demonstrated 40 dB of gain with 12% DC to RF efficiency. The design considerations of power output, efficiency, bandwidth, size and thermal description are discussed from the viewpoint of potential space application. Also discussed are combining philosophy and package layout. Actual experimental results are presented.
    • 20 GHz MULTISTAGE FET POWER AMPLIFIERS

      Sokolov, V.; Saunier, P.; Bennett, R.C.; Lehmann, R.E.; Texas Instruments Incorporated Central Research Laboratories (International Foundation for Telemetering, 1981-10)
      A GaAs FET power amplifier module operating in K-band is described. The module has integral input and output WR-51 waveguide ports and incorporates a pair of low-loss waveguide to microstrip transitions. Single-stage and multi-stage microstrip FET amplifiers are fabricated on individual copper carrier blocks incorporating in-package impedance matching. Six packaged amplifiers are cascaded to achieve a 0.5 W, 30 dB gain amplifier module operating over the 17.7-20.2 GHz band.
    • 30 GHZ IMAGE ENHANCED MIXER “FRONT-END” FOR SPACEBORNE LOW NOISE RECEIVER USAGE

      H. DeGruyl; Ng, E.; Okean, H.C.; Steffek, L.J.; Tallerico, T.; LNR Communications, Inc. (International Foundation for Telemetering, 1981-10)
      A Ka-band low noise “front-end” currently under development for ultimate spaceborne receiver deployment, consists of a 27.5-30 GHz image-enhanced mixer integrated with a 3.7-6.2 GHz FET low noise IF amplifier and driven by a self-contained 23.8 GHz phaselocked LO source. The image enhanced mixer, designed for 5 dB overall “front-end” SSB noise figure, utilizes a balanced pair of in-house high quality GaAs Schottky mixer diodes embedded in a composite waveguide/TEM “crossbar” balanced mixer structure possessing inherent mutual RF/LO isolation. The three stage FET IF amplifier, implemented in a single-ended microstrip configuration, has, in a preliminary breadboard, exhibited 24.5 ±0.5 dB gain and 1.5 to 2.4 dB noise figure over the 3.7-6.2 GHz band. The LO source, consisting of a C-band high power FET VCO, phase locked to an external 500 MHz crystal reference, and driving a C-to-K band varactor quadruplet, will provide up to 40 mW LO drive at 23.8 GHz.
    • ACCURATE ANTENNA REPOINTING FOR PATTERN MAPPING

      HOLTZ, L. VAN; European Space Research & Technology Center (International Foundation for Telemetering, 1981-10)
      The attitude control system of the European Space Agency’s Orbital Test Satellite (OTS) was originally designed for nominal earth pointing with only limited bias capability (of up to 2.5° in pitch and roll) which is more than adequate to remove earth sensor/wheel misalignments that could be incurred during or following launch. Subsequently, a need was expressed to support off-nominal coverage missions and antenna mapping tests. A method was thus defined that would provide greater repointing capability (up to 4.6°) while retaining the accuracy available with the precision infrared sensor. The method is outlined, and the repointing limitations indicated that are inherent to the OTS sensor design (13° in roll and 7° in pitch). Operations and conditions are stated that enable these extremes to actually be reached. The error budget is presented for the case of antenna mapping, demonstrating that attitude restitution can be made so that beam centre position can be determined to an accuracy of 0.1° half cone angle. The significant advantages of the described method are that only one ground station is required, and that results can be available within 24 hours following completion of the test. Results obtained with OTS are referred to, that support the claims. Finally desirable design modifications are discussed that could allow further increases in repointing capability of future satellites.
    • ACQUISITION OF ARTILLERY PROJECTILE DATA DURING IN-BORE TRAVEL USING RF TELEMETRY

      EVERSWlCK, DAVID N.; GLASS, LEON H.; HARRINGTON, ROBERT J.; U. S. ARMY ARMAMENT RESEARCH AND DEVELOPMENT COMMAND (International Foundation for Telemetering, 1981-10)
      The U. S. Army Armament Research and Development Command (ARRADCOM), has had a need for a number of artillery projectile telemetry systems to obtain in-bore and inflight data. This paper provides a brief description of some of these systems along with the non-destructive testing techniques that have been utilized for verifying the gun hardness of telemetry components and systems. Examples of in-bore environmental data obtained during actual firings are presented and discussed.
    • ACQUISITION, PROCESSING, AND APPLICATIONS OF METEOROLOGICAL SATELLITE DATA AT THE AIR FORCE GLOBAL WEATHER CENTRAL

      Major Johnson, William R.; HQ Air Weather Service (MAC) (International Foundation for Telemetering, 1981-10)
      The Air Force Global Weather Central (AFGWC) is the world’s largest military meteorological facility. A large portion of its men, women, and computer resources are dedicated to the acquisition, processing, display, and application of meteorological and space environmental data. In this paper, I will address only meteorological and space environmental data.
    • ADAPTIVE INTERFERENCE REJECTION FILTERS FOR SPREAD SPECTRUM COMMUNICATION SYSTEMS

      Masenten, W. K.; Hughes Aircraft Company (International Foundation for Telemetering, 1981-10)
      Use of spread spectrum techniques for communication systems has proven an effective technique for increasing the ECCM capability. This technique has, however, increased the systems susceptibility to narrow band interference because of the larger bandwidth occupied by spread spectrum waveform. This vulnerability is further compounded by the interferers often being in close proximity to the receiver and the dynamic nature of the interference environment. The adaptive filter is a technique for suppressing interferers whose spectral characteristics are different from those of the signal of interest while passing the data with a minimum of phase and amplitude distortion. The adaptive filter can be realized as a steerable notch filter or a fully adaptive transversal filter following the development by Widrow. Use of the adaptive filter as a pre-filter or whitening filter prior to the demodulator is discussed. The advantage of suppressing high level narrowband interference prior to the demodulator, especially when the demodulators are implemented digitally is the main motivation. An important consideration is the ability of spread spectrum systems to tolerate a substantial loss of spectral energy while still maintaining the desired performance. This feature allows use of steerable filters with relatively wide notches or correspondingly transversal filters without a large number of coefficients. Finally, implementation of adaptive transversal filters with surface acoustic wave (SAW) and charge coupled devices (CCD) is discussed.
    • ADAPTIVE TRENDS AND DESIGN CONSIDERATIONS FOR LARGE REFLECTOR ANTENNAS

      Rootsey, James V.; Electromagnetic Technology Section Harris Corporation (International Foundation for Telemetering, 1981-10)
      This paper looks at the fundamental qualities of large reflector antennas that make them vulnerable to interference, and reviews the recent trends toward passively and actively placing deep nulls in the direction of unwanted signals. The basic limitations of adoptively controlling the sidelobes of large reflector antennas are presented. The effectiveness of cancelling sidelobes without disturbing the main beam is described and verified with measurements taken during experiments at Harris’ facility.
    • ADVANCED 14/12 AND 30/20 GHz MULTIPLE BEAM ANTENNA TECHNOLOGY FOR COMMUNICATIONS SATELLITES

      Chen, C.C.; TRW Defense and Space Systems Group (International Foundation for Telemetering, 1981-10)
      This paper discusses recent TRW advances in communications satellite antenna technologies for the 14/12 and 30/20 GHz bands. The 14/12 GHz antenna system provides 15 or more high gain, low sidelobe spot beams for contiguous coverage of the CONUS for point-to-point communications, or four contoured time zone beams for direct broadcast service. A 2-meter offset reflector has been built and tested to demonstrate the frequency reuse and beam isolation capabilities of the antenna. The 30/20 GHz antenna system provides 10 to 20 fixed beams for large volume traffic trunking service and six independently scanned beams for customer-premise-service within the CONUS. A proofof- concept model antenna for proving the technology feasibility is currently under development.
    • ADVANCED COMSAT SYSTEM DESIGN

      Holmes, W. Morris; TRW Defense and Space Systems Group (International Foundation for Telemetering, 1981-10)
      Current Domestic C-Band Satellite Systems in the United States all operate in a distribution mode, in that all information is transmitted to the entire satellite coverage area. These systems are optimum for television distribution and other information channels requiring simultaneous delivery to many receive terminals. For point-to-point communications current satellite systems provide very inefficient use of the spectrum/orbit resource. This paper recommends use of multiple beam C-Band satellites with frequency reuse in different geographic locations. This approach can provide more than ten times as much communications for each orbit slot. Compatibility with current systems is shown to limit satellite EIRP and G/T, so that the satellite required is relatively easy to implement.
    • ADVANCED MANEUVERING REENTRY VEHICLE INSTRUMENTATION AND COMMUNICATION TECHNIQUES

      Galleher, G. W.; Locklair, A. J.; McDonnell Douglas Astronautics Company (International Foundation for Telemetering, 1981-10)
      This paper describes instrumentation and communications techniques used in the data gathering process for presently on going high performance advanced maneuvering reentry vehicle test flights. Transducers and signal conditioning design considerations including flight test results of vibration and acoustic data (gathered simultaneously by eight FM and one 24,824 sps PCM channel), nose and control surface load cells, control actuation, flow rates, control and aerodynamic pressures, heat shield in-depth thermocouples, nose recession (nuclear and acoustic) are discussed. Also presented are the instrumentation techniques used to verify the integrity of the RF subsystem in addition to a description of the PCM, Data Delay and FM video links.
    • THE AIR FORCE SATELLITE CONTROL FACILITY OPERATIONS

      Kluetmeier, Jorn; The Aerospace Corporation (International Foundation for Telemetering, 1981-10)
      The Air Force Satellite Control Facility (AFSCF) originated over twenty years ago, and has evolved into a global satellite support network. This global network includes seven Remote Tracking Stations (RTSs), support elements, and the Satellite Test Center (STC) located in Sunnyvale, California. The AFSCF provides real-time telemetry, tracking, and commanding (TT&C) support to Department of Defense (DoD) spacecraft and launch vehicles. Since its inception in response to changing DoD space support requirements, the AFSCF network has grown through expansion and modernization of its tracking, data processing, and communication capabilities. The AFSCF network supports over 52,000 satellite contacts per year. This paper describes the operations performed in support of one of these contacts.
    • THE AMSAT PHASE IIIB SPACECRAFT

      Kasser, Joe; King, Jan; The Radio Amateur Satellite Corporation (AMSAT) (International Foundation for Telemetering, 1981-10)
      The AMSAT Phase IIIB spacecraft is the second in the third generation of communications satellites in the (Radio) Amateur Satellite Service. It is designed to provide worldwide communications to the global radio amateur community, for hours at a time each day, using a single spacecraft. The spacecraft is designed to require a minimal amount of ground control and incorporates a single RCA 1802 based microcomputer that performs all the altitude control, command, decoding, and telemetry processing functions. This flight computer operates in a multitasking environment and incorporates a number of unique hardware and software features, including the absence of ROM (it is totally RAM based) and the incorporation of a high-level software language developed in Germany, known as IPS, which belongs to the FORTH family of languages.
    • ANALOG ENCRYPTION AND TRANSMISSION OF ANALOG SIGNALS

      Chethik, Frank; Western Development Laboratories Division (International Foundation for Telemetering, 1981-10)
      A method of encryption and transmission of analog signals is presented in which Pulse- Amplitude-Modulation, Frequency Modulation (PAM-FM) techniques are used. This method has the potential for increased capacity over bandwidth constrained channels with no loss of privacy when compared to the current practice of Pulse-Code-Modulation, Phase-Shift-Keying (PCM-PSK). The techniques are described, and quantitative comparative analyses are given. A fading channel scenario is developed in which the capacity of PAM-FM with analog encryption is shown to be twice that of PCM-PSK.
    • ANTIJAM PERFORMANCE OF CODED FH/MFSK

      Huth, Gaylord K.; Tokunow, Lawrence S. (International Foundation for Telemetering, 1981-10)
      Frequency hopping (FH) is a powerful antijam spread spectrum modulation when combined with multiple-frequency-shift-keying (MFSK) and error correction coding. This paper determines the antijam message error rate performance of various formats of FH/MFSK with convolutional error correction coding techniques. The worst case jammer is determined for each signalling format and coding technique and the antijam performance for all configurations are compared.
    • THE APPLICATION OF ADVANCED TECHNOLOGY TO NAVAL HF COMMUNICATIONS ARCHITECTURE

      Townsend, David H.; U.S. Naval Research Laboratory (International Foundation for Telemetering, 1981-10)
      HF communications are a necessary and vital part of Naval communications. The application of low noise, wide bandwidth HF architectures in satisfaction of this need will be discussed. The development of state of the art, frequency-agile receivers and exciters, decade bandwidth power amplifiers, software programmable modems, and the shipboard architectures exploiting these capabilities will be described.
    • APPLICATION OF ERROR-CORRECTING CODES IN DATA TRANSMISSION SYSTEMS WITH BIPHASE MODULATION

      Gao, Jiapens; Chengdu Institute of Radio Engineering (International Foundation for Telemetering, 1981-10)
      The polarity uncertainty in coherent demodulation of biphase signal raises a new question to the application of error-correcting codes. In this paper the real capability of errorcorrecting codes used with differential biphase modulation is analysed and, with the special cases of cyclic Hamming codes and two BCH codes, the degree of performance deterioration is estimated. Three methods for solving polarity inversion with preserving the error-correcting capability at the cost of one information bit lost are proposed. Practical implementation of these methods is briefly discussed.
    • APPLICATION OF REGRESSION ANALYSIS TO VIDEO DIGITAL DATA FOR DETERMINING PROJECTILE IMPACT LOCATIONS

      Robertson, Greta; Hughes Helicopters, Inc. (International Foundation for Telemetering, 1981-10)
      The correlation of two grid systems can be estimated by application of regression analysis to data whose relationship is assumed to be explained by linear transformation model. The two grid systems are a surveyed target range and real-time video of the range during testing of 30mm chain gun/2. 75"FFAR conducted for research and development of the YAH-64 Advanced Attack Helicopter (AAH) target acquisition and weapons system. The regression model and computational method are discussed; analysis of the impact location determination errors, operator error and errors due to skewness, introduced by camera position and orientation, are presented.
    • APPLICATIONS OF GPS PHASE COHERENCY

      Martin, Edward H.; Collins Government Avionics Division (International Foundation for Telemetering, 1981-10)
      The capabilities inherent in the Global Positioning System carrier and code modulation waveform provide an extremely precise and coherent spaceborne signal which may be applied to a variety of applications beyond the classical function of navigation. A description of rnechanizations based on both short and long baseline interferometry is given leading to applications for space vehicle attitude determination, azimuth bearing and level estimation, and precise survey location. Utilization of carrier phase changes is examined for dynamic vehicle surveys to provide a capability for accurately measuring gravity deflections in a real-time operational data processing system.
    • AN ARCHITECTURAL DESIGN OF AN FDMA/TDM BASEBAND PROCESSOR FOR 20/30 GHZ SATELLITE COMMUNICATIONS SYSTEM

      Jean, P. N.; Neal, W. R. (International Foundation for Telemetering, 1981-10)
      An architectural design of a baseband processor to provide on-board processing for a 20/30 GHz communications satellite is presented. The operation of this processor is explained in some detail. Major assumptions, considerations and goals that shaped the design of the baseband processor are identified and discussed. Since a primary benefit of on-board processing is flexibility, systems employing a processing satellite system will need versatile network protocols. A two-level network protocol that permits users to specify various parameters of their message links and to use different routing protocols on a message-by-message basis is presented here.