• SCIENCE AND APPLICATIONS SPACE PLATFORM COMMUNICATIONS AND DATA MANAGEMENT SYSTEM

      Kasulka, L. H.; McDonnell Douglas Astronautics Company (International Foundation for Telemetering, 1981-10)
      The development of space platforms represents the next logical step in the exploration and utilization of space. Such platforms promise cost-effective means for performing both scientific and applications missions, such as surveys of Earth resources, for example, in low Earth orbit. Payloads mounted on these platforms can perform missions for longer periods of time than are currently available to payloads mounted in the Shuttle’s payload bay. In addition, these platforms can provide a variety of services, including a centralized power source, command and data acquisition, communications, pointing and environmental control, as well as periodic Shuttle visits for performing maintenance tasks, replenishing consumables, and replacing payloads. These platforms must be able to provide data and communications services to groups of payloads consisting of individual payloads that may or may not have common objectives and operating characteristics, and where the payload mix on a platform changes periodically during the orbital life of the platform. Appropriate data systems can be provided to support a platform development program and modest extensions of existing technology will allow these platforms to accommodate the evolution of payloads foreseen through the 1980’s.
    • A SEQUENCY DIVISION MULTIPLEX SYSTEM

      Qishan, Zhang; Mingrui, Zhang; Yaokun, Liu; Beijing Institute of Aeronautics & Astronautics (International Foundation for Telemetering, 1981-10)
      A sequency division multiplex (SDM) system using Walsh subcarriers was developed for the transmission of telemetry signals at our laboratory The basis of mathematics which can form a telemetry system is orthogonal function. It is the Walsh function that may form a new telemetry system. At the first stage a baseband transmission system has been designed and tested. It shows that the results of experiments are quite good, and the new system works well. At a second stage FM is used as carrier transmission. Now the whole system can work property. A proper choice of the subcarriers minimizes the crosstalk. Principles for the selection of Walsh subcarriers are deduced. It seems that the SDM system has great potentialies.
    • SIGNALING PERFORMANCE OVER A PIECE-WISE LINEARLIMITED CHANNEL IN THE PRESENCE OF INTERFERENCE AND GAUSSIAN NOISE

      HUANG, T. C. (International Foundation for Telemetering, 1981-10)
      Presented here is a model and analysis for evaluating bit error probability of a BPSK signal transmitted through a piece-wise linear (PWL) limited channel subject to a CW interference as well as additive Gaussian noise. The CW interference is assumed to have a random phase Θj over (0, 2π) and a fixed frequency fj which may be either inband or outof- band of the signal channel band. The analysis is carried out in two steps: First an explicit expression for the desired signal, CW tone and their harmonics conditioned on the uplink channel noise if obtained at the output of a PWL limiter. Each of these CW tones and harmonics is modeled into two components--one sinusoid with a mean power and coherently related to Θj and an equivalent Gaussian noise, independent of each other. This equivalent Gaussian noise is also independent of the noise component associated with the desired signal. The interference model is reasonable provided that the frequency fj is not close to the carrier frequency of the signal. Based on the interference model, a conditional error probability expression, whose statistics are constructed through known moment techniques, is formed and averaged over the appropriate random variables. Numerical results for interference model and error rate curves will be compared with those of hardlimited channels in order to illustrate the effect of a PWL limiter.
    • SOFTWARE IN DEVELOPMENT FLIGHT TEST PACKAGES

      Maschoff, Leon W.; Sandia National Laboratories (International Foundation for Telemetering, 1981-10)
      This report discusses application software options that are available for the design of development flight test microprocessor packages. Prelaunch parameter updates, telemetry channel calibration, system and processor self-test, raw data store, reduced data store, and telemetry formatting are some of the on-board functions that software can perform in addition to the customary control and arithmetic calculation tasks. A specific application that implements these functions as software modules and the hardware needed for support is described. The hardware in this application includes a 16-bit microprocessor that is dedicated for real time operations and an 8-bit microprocessor that services the self-test functions.
    • SOFTWARE IN DRONE CONTROL

      Shaver, Robert L.; Sandia National Laboratories (International Foundation for Telemetering, 1981-10)
      High performance multi-use drones require complex control capability. Distributing the communications, control and navigation functions among different microprocessor systems connected in a network improves performance and reliability. Assembly language provides the means of optimizing time critical functions of communications and I/O control, which high level languages, such as PASCAL, ease development of mission management requirements. The use of real-time operating systems (RTOS) permits co-processing of a variety of functions in overall drone operation management. The RTOS is a software “bus” providing communications network for modules. Functions and modules are assigned priorities, enabled or suspended as needed to perform mission operational requirements via the RTOS.
    • SOLID STATE WIDEBAND POWER AMPLIFIER DEVELOPMENT AT 20 AND 44 GHz

      Ngan, Y.C.; Sun, C.; TRW (International Foundation for Telemetering, 1981-10)
      Two amplifier developments centered at 20 GHz based on GaAs IMPATT diodes will be discussed. The on-going developments of a 20 GHz communication amplifier sponsored by NASA Lewis using injection locking and resonant cavity combiner will be reviewed. A wideband 20 GHz amplifier to achieve 20 Watt 1 GHz bandwidth based on 3-dB hybrid couplers and stable mode of amplification, along with the results obtained from the constant voltage mode of amplification will be discussed. A wideband solid state amplifier designed as a driver for a 44 GHz terminal transmitter will be described. The amplifier is designed for 2 GHz 1-dB bandwidth centered at 44.5 GHz, with an overall gain of 40 dB. A six-stage design is used to accomplish 500 mW output power. Low cost construction and mechanical ruggedness are emphasized in this design.
    • SPACE RADIATION HARDENING AND VLSIC TECHNOLOGY

      Josephson, Vernal; The Aerospace Corporation (International Foundation for Telemetering, 1981-10)
      Military Space Systems are required to have a certain level of immunity to all possible space radiation effects experiences during mission life time. These include upset and latchup from weapon x-ray bursts and cosmic rays, photo current burn-out of active junctions by large prompt doses of radiation, and performance degradation from accumulated dose due to enhanced radiation belts. Procuring piece parts capable of performing mission requirements and providing the desired immunity to these effects, and testing to verify the desired satellite immunity presents problems which must be considered when contemplating massive use of VLSIC technology where even higher desired levels of immunity may be desired. The techniques used for hardening and the testing required for hardness assurance will be discussed with emphasis on their application to VLSIC technology and its potential in space applications. An overall satellite was subjected to irradiation in order to verify its immunity to space radiation. These results will be discussed below.
    • SPACE SHUTTLE ORBITER TELEMETRY/COMMAND DESIGN ASPECTS AND FLIGHT TEST RESULTS

      Muchow, Lee; Hoagland, J. C.; Rockwell International (International Foundation for Telemetering, 1981-10)
      During the first flight of Columbia (STS-1), the Instrumentation, Communications, and Tracking Subsystems (I-C&TSS) of the Space Shuttle orbiter used S-band links to provide (in addition to tracking) reception of digitized voice, commands, and printed or diagrammatic data at a maximum rate of 72 kilobits per second (kbps). The subsystem also provided a transmission capability for digitized voice, telemetry, television, and real-time and recorded data. Communication was via S-band directly to the ground stations; ultrahigh frequency (UHF) voice was used for communication with the landing site and some ground stations and for providing a backup link for state vector update. Audio and television subsystems served on-board needs and interfaced with the radio frequency (RF) equipment. Provisions were provided to record on-board data for post-flight playback. During aerodynamic flight following entry, the S-band link was used to supplement the UHF link that provides two-way simplex voice communication with air traffic control facilities. The I-C&T subsystem for STS-1 operated with almost textbook performance; exceptions were a dedicated signal conditioner redundancy failure, failure of the development flight instrumentation PCM recorder, and some measurement sensor failures.
    • SPEECH PERFORMANCE TESTS FOR VOICE PROCESSORS

      Uzdy, Z.; The Aerospace Corporation (International Foundation for Telemetering, 1981-10)
      Voice processors, including those using linear predictive coding (LPC) algorithms, are becoming more prevalent in communication systems. Several intelligibility and speaker recognition tests were used to evaluate two currently available LPC voice processors. Both text-dependent and text-independent techniques were developed. The tests are aimed at potential users, yielding quantitative data that permit performance comparisons both of systems and of human speakers and listeners.
    • STATE-OF-THE-ART ASSESMENT OF IN SITU CALIBRATION EQUIPMENT

      Webb, Roger L.; Science Applications, Inc. (International Foundation for Telemetering, 1981-10)
      Automated Calibration Systems (ACS) represent the state-of-the-art in calibration of test measurement and diagnostic of equipment (TMDE). The features and capabilities of two systems in use by the U.S. Navy are discussed in this paper. The Centrally Operated System for Metrology Information Control (COSMIC) and the Metrology Equipment Calibration and Control Analysis (MECCA) system are being developed to greatly reduce the cost of calibrating a very large inventory of test equipment at sites around the world. The benefits of an in situ calibration capability has been demonstrated at the Naval Calibration Laboratory, Tustin, California, where these calibration systems have been integrated with online databases. Future advances are anticipated through simpler human interfaces and higher throughput rates. The in situ systems now coming into use offer significant material, calibration and repair cost savings. Improved calibration support will benefit most telemetry, communication, and weapon systems.
    • A Survey of Modern Instrumentation in Aerospace TT&C Earth Terminals

      Cuccia, C. Louis; Steinberg, Philip; Ford Aerospace & Communications Corp. (International Foundation for Telemetering, 1981-10)
      This paper will provide an overview of the instrumentation of aerospace telemetry/systems in mobile and stationary earth terminals, using integrated circuits and LSI technology, microprocessors, computer graphics and measurement system. This instrumentation includes not only circuits to handle TT&C data, but also to analyze display and control system performance from the RF portion including considerations of sensitivity and effective radiated power, to tracking measurements, baseband and data system performance; to man-machine interfaces. This paper will also discuss modern display systems and techniques and will introduce the advantages of the use of the IEEE standard 488-1978 and RS-232 interface buses for the control and monitoring of TT&C equipment, including data processing with particular application to survivable earth terminals.
    • SYSTEM ASPECTS OF SCANNING BEAMS FOR WIDELY DISTRIBUTED USERS

      Kolba, Dean P.; M.I.T. Lincoln Laboratory (International Foundation for Telemetering, 1981-10)
      Satellite communications in the allocated EHF bands, (i.e., several frequency segments from ~20 GHz to 50 GHz) has the potential for providing interference resistant communications to users employing small, mobile terminals. To realize this potential, advanced spacecraft technologies are required, such as uplink coverage through high gain directive beams, onboard signal processing, and downlink beam hopping. Simultaneous worldwide uplink coverage could be obtained via many narrow uplink antenna beams which collectively cover the earth field-of-view. When worldwide communications traffic is low volume, a reduction in space segment impact can be achieved by using a few narrow uplink antenna beams to provide the required service. To minimize delays, these beams must be able to rapidly point anywhere within the field-ofview to cover individual users who require a channel for brief communications. The agile antenna beams can be shared through demand assignment techniques. A multimode common transmission format can provide both data and control channels. The data channels are available at several rates to allow either full duty cycle data transmission or burst data transmission. With burst transmissions, a single beam can support multiple calls in a time division multiplexed fashion. The control channels are utilized in coordinating the use of satellite resources to efficiently meet the communications needs of the users. This paper discusses the use of EHF satellite communicatons to provide service to widely scattered users. The use of control channels to request and coordinate service is described. Example control protocols are presented, and system performance is indicated.
    • TDRS ANTENNA AUTOTRACK LOOP

      Schmeichel, Harry; TRW Defense and Space Systems Group (International Foundation for Telemetering, 1981-10)
      The Tracking Data and Relay Satellite (TDRS) has two large, gimballed antennas which will relay information between earth-orbiting satellites and a ground terminal in New Mexico at data rates up to 300 million bits per second. This relay service requires closedloop tracking of user satellites at K-band frequencies with a pointing accuracy of 0.06°. An autotrack loop, closed through a ground-based computer, performs this RF beam pointing function for each single-access (SA) antenna. The autotrack system basically consists of two stepper motors to move the antenna, an onboard RF monopulse system to sense the pointing error and command generation equipment on the ground to close the loop. It is shown how system models and observations are combined to stabilize and improve the pointing performance of this lowbandwidth, closed-loop tracking system. Antenna pointing performance is demonstrated by simulation.
    • TDRSS ANTENNAS GROUND STATION AND SPACEBORNE

      Butts, C. J.; Gutwein, T. A.; Harris Corporation (International Foundation for Telemetering, 1981-10)
      Three sixty foot diameter Ku-Band Antennas have been completed as part of the Tracking and Data Relay Satellite System (TDRSS) at the NASA Johnson Space Center, White Sands Test Facility. These very high efficiency satellite communication antennas provide in excess of 68dBi directivity. Further characteristics include autotrack accuracy of 0.01E, frequency reuse, and surface accuracy within less than .02" rms of the desired shaped surface. Two TDRSS antennas weighing less than 52 pounds are ready for launch aboard each satellite. These 16 foot deployable antennas provide frequency reuse performance in two frequency bands - Ku and S. As with the sixty foot antenna, shaping of the subreflector and main reflector is utilized to achieve high aperture efficiency. This paper describes some of the design, analysis and measurement techniques used in the development of these antennas.
    • TDRSS CONTROL NETWORK

      Manders, Robert H.; TRW Defense Systems Group (International Foundation for Telemetering, 1981-10)
      The new NASA near-earth orbit tracking and data acquisition network will be made up of a network of two, synchronous orbit, tracking and data relay satellites plus an in-orbit spare. The principal ground components are the TDRSS White Sands Ground Terminal (WSGT) near Las Cruces, New Mexico and the Network Control Center at NASA GSFC in Greenbelt, Maryland. Communications between the sites are handled via the NASA Communications Network (NASCOM) through the NASA Ground Terminal (NGT) located at the WSGT. This paper will discuss the control of the TDRSS Network for User Spacecraft Tracking and User Data Acquisition.
    • TDRSS GROUND SEGMENT PERFORMANCE

      Matchett, M.W.; Government Communications Systems Division (International Foundation for Telemetering, 1981-10)
      About 150 racks of fully-automated equipment provide tracking, user traffic transmission and reception, simulation, and verification services for users of NASA’s Tracking and Data Relay Satellite System (TDRSS). Installation of this equipment in the White Sands Ground Terminal Facility is now complete and final testing is nearly complete. This paper describes the implementation and performance of that portion of the ground segment equipment provided by Harris. Major equipment groups described are 1) antennas, 2) user traffic link forward (transmit) equipment, 3) S-band single-access return (receive) equipment, 4) K-band single-access return equipment, 5) multiple-access RF equipment, 6) range and range-rate equipment, 7) user spacecraft simulation equipment, and 8) system verification equipment.
    • THE TECHNOLOGIES OF AUTONOMOUS SPACECRAFT MAINTENANCE

      Elowitz, Murray L.; Wong, Bill C.; TRW Space and Technology Group (International Foundation for Telemetering, 1981-10)
      Autonomous spacecraft maintenance (ASM) is the term used to describe the capability of a spacecraft to perform its maintenance functions without frequent, regular ground support and interactions. This new spacecraft attribute is needed to enhance the survivability and availability of our satellites, as well as to reduce operational support costs. This paper explains the concept of ASM as it has evolved. Generic requirements are given and explained for a latter 1980's capability. Spacecraft architectural changes are required, involving a mixture of technology adaptation and advances. Technology developments required to meet the requirements are identified and assessed. Significant advances are needed in system and subsystem technology areas to create a posture for building an ASM capability. With WWMCCS increasing reliance on spacecraft for both communication and sensor data, the issues of ASM are of vital importance to this community.
    • TECHNOLOGY DEVELOPMENT FOR A K-BAND BEAM-HOPPED SATELLITE DOWNLINK

      Berglund, Carl D.; Dolbec, Richard E.; Stevens, Mark L.; M.I.T. Lincoln Laboratory (International Foundation for Telemetering, 1981-10)
      A beam-hopping system utilizing a phased array and solid-state power amplifiers has previously been introduced for application in EHF communications satellites. The performance of a 5-bit P-I-N-diode phase shifter developed for use at 20 to 21-GHz is presented. The development and characterization of 0.5-W K-band GaAs MESFETs is discussed together with their performance capability. The performance of experimental amplifier designs is included.
    • Telemetering Standards Coordination Commitee

      McAnally. Claude W. (International Foundation for Telemetering, 1981-10)
    • TELEMETRY AND TELECOMMAND DATA PROCESSING FOR THE GERMAN SPACE PROGRAM

      Piotrowski, Peter; German Space Operations Center (International Foundation for Telemetering, 1981-10)
      The data system for the processing of telemetry and telecommand data for the German space research program is in the process of being implemented. It consists of data processing, monitoring and transmission facilities including hardware and software at the ground station with various antennas and at the mission control center. The system is designed on distributed processing techniques based on processors of various sizes. The software is modular and can easy be adjusted for the various mission requirements. Data transmission is based on. standard protocolls.