• ON-BOARD PROCESSING FOR ATTITUDE CONTROL OF APPLE

      Mirugesan, S.; Rao, C. Kameswara; Shanmugam, C.N.; Goel, P.S.; ISRO Satellite Centre (International Foundation for Telemetering, 1981-10)
      APPLE, India’s first three axis stabilised communication satellite, was launched by the ARIANE launcher on June 19,1981. The communication payload operates in C-band (4-6 GHz) and facilitates experiments in communication technology and its applications. Attitude and Orbit control System (AOCS) of APPLE, whose on orbit performance is satisfactory despite the non deployment of one of the solar panels, is briefly described. Various functions on the Attitude Control Electronics (ACE) are described with details on processing schemes for Pulsewidth Pulse Frequency Modulator, Yaw error computation using hybrid SINE convertor, Magnetic torquer control and Thruster selection. Further, future trends in onboard processing for communication satellites are highlighted.
    • ON-BOARD PROCESSING FOR THE NOVA SPACECRAFT

      Whisnant, J. Miller; Jenkins, Robert E.; Utterback, Harry K.; The Johns Hopkins University (International Foundation for Telemetering, 1981-10)
      A major hardware change to the TRANSIT Navy Navigation Satellite System (NNSS) is underway. A new generation of satellites called NOVA are being built which have onboard a general purpose minicomputer, high precision clock, orbit adjustment system (OATS), and disturbance compensation system (DISCOS). This paper describes the software and processing for the on-board computer. The software is a system of interrupt driven, real-time programs which perform various data management and control functions and allows great flexibility in the operation of the satellite. In addition to loading special programs and data and dumping specified regions of memory, data management includes loading and then retransmitting navigation message data and collection of both telemetry (TM) data and DISCOS thruster firing data. Through its interface with the spacecraft TM and command systems, the on-board computer also serves as a powerful control device, especially in the orbit adjust phase immediately after launch. It has already been demonstrated with a previous version of these satellites that this highly flexible software system can be quickly reconfigured after launch to recover from failures to other satellite hardware systems. Also described in this paper are other satellite subsystems which interact with the flight computer and the system of ground support computers and software.
    • ONBOARD PROCESSING FOR COMMUNICATIONS SATELLITES

      Davies, R.S.; Chethik, F.; Kota, S.L.; Ford Aerospace & Communications Corporation (International Foundation for Telemetering, 1981-10)
      Future satellite networks may include satellites that provide multiple uplink and downlink coverage antenna beams together with signal processing subsystems. Where the number of earth terminals is large and the traffic is diffuse, efficient methods for routing signals need to be developed. This paper addresses the switching and routing processes for both long term connections (stream traffic) and short messages (burst traffic). Onboard routing appears most efficient for burst traffic where as stream traffic is best handled by means of a ground based traffic controller. An integrated control system concept is suggested together with access and multiplex formats to accommodate mixed traffic.
    • THE PARTICULATE NOISE POWER SPECTRUM OF A MAGNETIC TAPE RECORDER/REPRODUCER

      Hedeman, Walter R., Jr.; Law, Eugene L.; Pacific Missile Test Center (International Foundation for Telemetering, 1981-10)
      This paper presents a theoretical derivation of the noise power spectrum of a magnetic tape recorder/reproducer. The theoretical results are shown to be in good agreement with experimental data.
    • PAYLOAD TECHNOLOGIES FOR THE EUROPEAN COMMUNICATION SATELLITES IN THE 90’s

      COIRAULT, R.; European Space Agency (International Foundation for Telemetering, 1981-10)
      New communication services are developing quite fast in Europe. At long term they will certainly be handled mostly by a terrestrial network with satellite links to complement when it is more cost effective. Future satellite payloads shall thus be designed to meet new demands especially as regards growing and fluctuating traffic patterns. Unfortunately, meaningful forecasts cannot be made, as yet. In this context, a payload technologies assessment exercise is presently being carried out by ESA. The scarcity of data concerning the expected traffic has been compensated for by the introduction of “pilot missions”. Although hypothetical they correspond to various scenarios and provide the required system background. This paper outlines the pilot missions characteristics and reviews the critical payload technologies which are concerned and ought to be developed in order to meet the next decades challenges. The “pilot missions” include: an extensive provision of specialised services in the 11/14 GHz frequency range, a very high capacity service at 20/30 GHz for a videocommunication application and a global service at L-Band for aeronautical, land and maritime mobiles. The associated technologies focus essentially on antennas and signal processors. The antenna sub-system must generate high gain spot beams. Low sidelobes requirements are also an essential characteristic in view of an efficient frequency re-use. Large reflectors will be necessary, with possibly a deployment in orbit. Complex and active feed networks will be implemented. On board signal processing represents another major break-through in payload technologies. RF switching matrices could be the baseline for the specialized services at 11/14 GHz. Regeneration with routing performed at baseband will be an essential feature of the 20/30 GHz application. At L-Band a data bus concept is an attractive approach.
    • THE PCM DROPOUT INDICATOR - A USEFUL DEVICE

      Hahn, J. C.; Rockwell International (International Foundation for Telemetering, 1981-10)
      During test and checkout of Space Shuttle systems, data is transmitted from test sites to processing centers via overland transmission lines and communication satellite. Loss of data (dropouts) may take place and can be attributed to a malfunction at the transmitting end, the receiving end or the transmission path itself. Before effective trouble shooting can begin, the cause must be isolated to a particular area or unit. The PCM Dropout Indicator is one of the devices used for this task.
    • PERFORMANCE BOUNDS FOR ANALOG SIGNAL ENCRYPTION

      Gersho, Allen; Dept. of Electrical & Computer Engineering (International Foundation for Telemetering, 1981-10)
      It is sometimes desirable to perform analog scrambling on an analog signal rather than digitizing the signal and performing digital encryption and transmission. Analog signal encryption is usually assumed to offer only a very limited degree of security. However, it is in fact possible to achieve perfect secrecy (just as is obtained with the one-time pad, for example) in encrypting an analog signal. The price paid for perfect secrecy is an inevitable degradation in the quality of the recovered analog signal. Under the constraint of perfect secrecy, the minimum possible degradation can be specified, at least in principle. This minimal degradation is a decreasing function of the key size for a fixed length message or key rate for an ongoing message. This bound on performance is determined by the rate distortion bounds for optimal digitization of the analog message.
    • PHASE NOISE MEASUREMENT SYSTEMS

      Lance, A. L.; Seal, W. D.; Labaar, F.; TRW Electronics and Defense (International Foundation for Telemetering, 1981-10)
      Phase noise is the term most widely used to describe the characteristic randomness of frequency. Automation of phase noise measurements has been developed with satisfactory results using two techniques referred to as the two-oscillator technique and the singleoscillator technique. Measurements are performed in the frequency domain using a spectrum analyzer which provides a frequency window following the phase or frequency detector. State-of-the-art systems include system modifications for cross-spectrum measurements and techniques used to improve the noise floor characteristics of the delay line FM discriminator in order to measure single sources which have very low phase noise characteristics.
    • PLANNING THE AFSCF OF THE FUTURE

      Carroll, James T.; The Aerospace Corporation (International Foundation for Telemetering, 1981-10)
      This presentation describes the Air Force Satellite Control Facility (AFSCF) planning cycle by use of decision package sets that will be incorporated in the DoD portion of the President’s budget. Major AFSCF projects reviewed include Data System Modernization; Remote Tracking Station (RTS) Modernization; Shuttle Support; Advanced Telemetry, Tracking, and Command; Transportable RTS; and the NASA Tracking Data Relay Satellite (TDRSS) interface with the AFSCF. Zero based budgeting using decision packages determine project priorities and approval levels. The benefit and task description of AFSCF major projects is described for the years 1983 through 1987. Long range priorities through the year 2000 are summarized.
    • PREPROCESSING IN TODAY’S TELEMETRY COMPUTER SYSTEM

      Hildebrand, Graham; Sangamo Weston (EMR Telemetry) (International Foundation for Telemetering, 1981-10)
      An increasing number of processes are being moved from the host computer to a versatile, smaller front end preprocessor. This paper discusses the reasons for preprocessing and presents a general purpose preprocessor. Use of the preprocessor in mapping MIL 1553 Multiplex Bus data is described as well as the more routine tasks of data merging and identification, compression, engineering units conversion, array forming, and data sorting.
    • PRESSURE RESISTANT BULKHEAD PENETRATORS FOR FIBER OPTICS IN DEEP OCEAN APPLICATIONS

      Cowen, Steven J.; Naval Ocean Systems Center (International Foundation for Telemetering, 1981-10)
      This paper describes results obtained at the Naval Ocean Systems Center, San Diego, under Independent Exploratory Development funding. The objective was to develop a robust, fully-demountable, high pressure penetrator design suitable for coupling light signals transmitted by optical fiber elements in an undersea cable operated at high ambient hydrostatic pressure into an electronics package or manned space. The feasibility of constructing such penetrators utilizing Graded Refractive INdex (GRIN) rod lenses as combination pressure barriers and imaging devices was demonstrated. Prototype realizations exhibited excellent optical throughput performance and readily survived in excess of 10,000 psi pressure differential as well as tolerating a wide temperature range. The design lends itself to hermetic construction for applications requiring no vapor diffusion over long mission durations. Such devices exhibit excellent potential for satisfying SUBSAFE requirements for manned submersible applications.
    • A PROGRAMMABLE-SIGNAL CONDITIONING PULSE CODE MODULATED TELEMETRY ENCODER

      ECKSTEIN, HOWARD M.; MICROCOM CORPORATION (International Foundation for Telemetering, 1981-10)
      The development of variable format airborne PCM data acquisition systems has generally been predicated upon advances in the field of solid state memory device technology. The introduction of Electrically Eraseable Programmable Read Only Memory (EEPROM) devices has generated renewed interest in the design of fully programmable PCM encoders. This paper will describe the evolution of one such micro-miniature PCM encoder system incorporating the following features: ∙ Complete Frame Format Program Capability ∙ Software Controlled Single Ended/Differential Input Program Capability ∙ Individual Sample - Gain/Offset Scaling Capability ∙ Hard Wire Program/Erase/Program Capability ∙ Variable Word Resolution ∙ Small Size
    • PROS AND CONS OF THE APPLICATION OF DATA ENCRYPTION TO NONGOVERNMENT COMMUNICATION

      Hoagland, J. C.; Rockwell International (International Foundation for Telemetering, 1981-10)
      This paper presents a philosophical approach to the contemporary question: Should data transmission within the commercial community employ encryption techniques and what are the advantages and disadvantages? The standard techniques of substitution, transportation, ciphers, codes, keys, synchronous systems, block messages, error correction, and time-sharing are defined for the reader to understand the many and varied techniques available. The properties of the techniques are outlined for further ease of understanding. A limited Glossary of Cryptography is included. The paper is an overview of the general subject of secure communication and does not discuss the theory of specific techniques in depth. Rather it will lead the reader to further explore the subject for theories and results applicable to specific applications.
    • PSEUDORANDUM CODE GENERATOR

      Dupuis, John J.; R & D Associates (International Foundation for Telemetering, 1981-10)
      This paper presents trade off considerations in design of a Pseudorandum Code Generator using a microprocessor or discrete circuits.
    • RANGE OVERVIEW PACIFIC MISSILE TEST CENTER

      Scott, Jay R.; Leslie, Ward J.; Pacific Missile Test Center (International Foundation for Telemetering, 1981-10)
      This paper provides an overview of the capabilities of the ranges operated by the Pacific Missile Test Center under the management of the United States Navy. Locations, types of instrumentation, operation, and current developments are briefly discussed.
    • RANGE SAFETY RECEIVER-DECODER FOR SPACE SHUTTLE LAUNCH VEHICLE

      Busby , Lawrence A.; Kramb, Edwin A. (International Foundation for Telemetering, 1981-10)
      Flight Termination Sub-Systems for range safety purposes are a part of all spacecraft launch vehicles. The Command Receiver and Decoder portion of this sub-system receives the rf up-link signal and initiates the flight termination action. For launch vehicles for unmanned spacecraft, the range safety up-link command signal is composed of selected IRIG audio tones, in a specified sequence, frequency modulated on an rf carrier. For the Space Shuttle launches, a more sophisticated high-alphabet modulation technique is used. This provides for a better probability against an undesired output caused by interfering signals. The Shuttle system uses a complex command modulation format composed of various audio tones frequency modulated on the standard UHF carrier. The characters in the command word are made up of two simultaneously transmitted tones selected from seven possible frequencies. These seven tones, taken two at a time, provide an alphabet of twenty-one different characters from which a command word is formed. The transmitted sequence of characters is selectable from mission to mission. Approximately 1012 possible code combinations exist for any one mission. For the Space Shuttle launches, the range safety Command Receiver-Decoders will be used on the Solid Rocket Boosters and the External Tank portions of the complex launch vehicle. The receiver section of these units is a single superheterodyne design fixed tuned to the proper rf center frequency at the time of manufacture. The decoder section utilizes a microprocessor to effect the decoding function. The decoder is “programmed” prior to flight to recognize only the code of the mission. In addition, the microprocessor is used to accomplish the audio tone demodulation using a Fast Fourier Transform (FFT) algorithm. Solid state output switches provide the decoder output voltages to the flight termination destruct mechanism.
    • RECENT DEVELOPMENTS IN NARROWBAND ANALOG SIGNAL ENCRYPTION WITH EMPHASIS ON VOICE CHANNEL SYSTEMS

      Udalov, Sergei; Axiomatix (International Foundation for Telemetering, 1981-10)
      In many instances, the process of telemetering of scientific information must be accompanied by a voice conversation which either reveals the sequence of measurements or provides information as to the nature of the data gathered and/or transmitted. If such voice information can compromise the integrity of the telemetry data to an unauthorized interceptor, voice privacy equipment must be used along with the equipment used for transmission of the telemetry data. The recent developments in LSI technology provide a new capability to the design of voice encryption equipment. This is particularly true for the case where sophisticated analog encryption schemes must be employed to permit the encrypted voice information to be transmitted over the existing telephone and radio channels which are typically limited to a 3 KHz upper-frequency cutoff. This paper examines the recent developments in analog voice privacy equipment design, as indicated by the disclosures made in open literature by various manufacturers and evaluators of such equipment. Advances in the technology as well as in analytical definitions of analog voice privacy are discussed. The role of such valuable LSI chips as a microprocessor and the DES algorithm are examined. Also, in addition to considering the classic frequency/time domain permutation algorithms, developments in analog “pseudonoise” scrambling are examined in view of the data made recently available in open literature.
    • A RELIABILITY IMPROVEMENT PROGRAM FOR THE ATLAS LAUNCH VEHICLE TELEMETRY PACKAGE

      Piontkowski, John S.; Stimadorakis, John; Tele-Dynamics of United Technologies; Omnitek, Incorporated (International Foundation for Telemetering, 1981-10)
      The scope of this paper deals with methods and processes undertaken to provide a significant reliability upgrade to an existing telemetry instrumentation subsystem. Selected components are produced using modern hybrid microcircuit technology in place of the previously configured discrete design approach. A comparative analysis is performed to demonstrate the resulting dramatic reliability improvement.
    • S BAND FLUSH ANTENNAS FOR THE SHUTTLE ORBITER

      Waineo, Douglas K.; Ellis, Haynes; Rockwell International Corporation (International Foundation for Telemetering, 1981-10)
      Two telemetry and communications antennas for the Shuttle Orbiter are described. Each antenna is circularly polarized and flush mounted under the thermal protection tiles. The quad antenna provides two beam positions selected by an electromechanical switch, and uses two cavity backed crossed dipole elements radiating through reduced size circular apertures called irises. The GPS/hemi antenna covers three frequencies, with 160E cone coverage at two L-band frequencies and 120E cone coverage at S-band.
    • SATELLITE COMMAND AND CONTROL ARCHITECTURE

      Col. Sanders, J. E.; HQ Air Force Satellite Control Facility (AFSCF) (International Foundation for Telemetering, 1981-10)
      This presentation will consist of a review of the DoD common-user Satellite Command & Control network to include: how the AFSCF evolved; a description of today’s satellite control network, its capabilities and limitations; a discussion of the approved upgrade program; and a view of what will be required for Satellite Command & Control for the 1990s.