• AUTOMATED DATA SYSTEM FOR HELICOPTER STRUCTURAL FATIGUE TESTING

      Carnicke, Allen S.; United Technologies Corporation Stratford (International Foundation for Telemetering, 1982-09)
      Helicopter structural fatigue testing requires the monitoring and precise control of physical input loads along with the collection and analysis of large quantities of static and dynamic data. This paper describes an automated, on-line system specifically designed to structurally test a full size helicopter airframe. Microprocessor controlled shakers apply dynamic loads to the test article and simulate a typical flight profile, e.g., take-off, climb, cruise, descent, hover and landing. A minicomputer based automated data system acquires up to 128 measurement channels consisting of outputs from accelerometers and strain gages with an overall data system throughput rate of 50,000 samples per second. The test engineer can select various operational and data processing formats from computer stored menus. Data tables in engineering units plus graphical displays of time histories or spectral information are also available. The system can be run in a variable data burst mode or in a continuous monitor mode.
    • S-BAND ACQUISITION AND TRACKING SYSTEM (SATS), WSMR SYSTEM FOR SPACE SHUTTLE ACQUISITION

      Blazosky, David M.; Kroeger, O. Paul; US Army White Sands Missile Range (International Foundation for Telemetering, 1982-09)
      The requirement for WSMR to independently acquire and track the NASA Space Shuttle presented WSMR with one of the basic problems associated with missile and air defense systems - acquiring and maintaining a precision track of an incoming target. The popular solution is to use two radars--a broad beam for acquisition and a narrow beam for precision track. The WSMR solution is the S-Band Acquisition and Tracking System (SATS) which uses two existing passive telemetry trackers (J-10 and J-67) in conjunction with WSMR precision track radars. The existence of an S-Band transmitter in the Shuttle made the use of the Telemetry trackers possible.
    • SPECTRAL SHAPE PREDICTOR FOR PCM/FM TRANSMISSIONS

      Brown, Roger W.; McDonnell Douglas Astronautics Company (International Foundation for Telemetering, 1982-09)
      This paper will demonstrate a computer application program to predict the spectral shape and IRIG-RF bandwidth required for a PCM/FM telemetry system. A filtered PCM bit stream is constructed from a Fourier series and used to FM-modulate the RF carrier. The Fourier transform of the FM-wave is calculated numerically, and voltage amplitude levels are plotted on a Tektronix graphic display. Several PCM bit patterns are used and a composite display is formed to approximate an actual PCM/FM spectrum. A comparison of predicted and actual spectra will be presented.
    • TRANSMISSION OF THERMAL IMAGE DATA USING PLUSE CODE MODULATION*

      Johnson, F. Bruce; Colorado Video, Inc. (International Foundation for Telemetering, 1982-09)
      This paper presents a method for synchronous conversion of infra -red image data to a Pulse-Code Modulation (PCM) bit stream for recording on instrumentation tape recorders. The PCM data recording method provides an improvement over analog FM recording in signal to noise ratio, horizontal resolution, and speed of data formatting. The methodology was applied to the design of a PCM encoder for an AGA model 680 Thermovision camera. The extension of the design to other devices is discussed. Considerations for the display of real-time and reduced speed data display on conventional television monitors are presented.
    • NASA DEEP SPACE NETWORK OPERATIONS CONTROL

      Weisman, William D.; Jet Propulsion Laboratory California Institute of Technology (International Foundation for Telemetering, 1982-09)
      Overall direction, coordination and control of the real-time activities of the NASA Deep Space Network (DSN) is the responsibility of the Network Operations Control Team located at the Operations Control Center at JPL in Pasadena. Real-time operation of the DSN is a complex task, requiring efficient interaction among operations personnel, hardware, software, communications and mechanical systems. Control is maintained by the team at JPL through allocation of responsibility for specific operational facilities to specific team members. The Network Operations Control Team is comprised of an Operations Chief, a Track Chief, and one or more Deep Space Station (DSS) Controllers. The Operations Chief is responsible for overall performance of the Operations Control Center, and provides a single point of interface with the Control Center to end user organizations. The Track Chief is responsible for overall performance of the DSN as a facility, while the Station controllers are assigned responsibility for monitoring and coordinating the operational activities at individual Deep Space Stations.
    • ISOTROPIC TAPE PERFORMANCE WITH MICROGRAP HEADS IN HDDR AND ANALOG MODES

      Lemke, James U.; Spin Physics, Inc. (International Foundation for Telemetering, 1982-09)
      High coercivity isotropic tapes recorded with very small head gaps (0.2 - 0.3μ) support magnetic transition densities exceeding 10,000 per millimeter (>250 KFCI) with practical densities of 133 KFCI. The signal is recorded vectorially within the medium with both longitudinal and perpendicular components contributing in-phase fields. Even with very small record gaps, substantial portions of both components in proximity to the head trailing pole are erased by the head field gradient subsequent to the initial record zone. Comparisons are made between longitudinal and isotropic media with regard to linearity and NPR in analog recording, and NPR in digital recording is examined.
    • International Telemetering Conference Proceedings, Volume 18 (1982)

      International Foundation for Telemetering, 1982-09
    • MIL-STD-1553 INTERFACES TO TELEMETRY SYSTEMS

      Nicolais, Ray; Ellis, Donald H.; AEROSYSTEMS ASSOCIATES; AYDIN VECTOR Division (International Foundation for Telemetering, 1982-09)
      With the advent of digital technology in aircraft systems, the need for advancements in digital data acquisition systems for flight testing became apparent. A thorough review of aircraft systems integration employing the MIL-STD-1553 multiplex data bus revealed the need for flight test systems that incorporate the advanced digital techniques and provide an interface to the data bus. This paper provides an overview of the MIL-STD-1553 requirements including word structure and protocol, with special emphasis on the requirements for synchronization and time tagging of the data acquired from the bus. The data bus is a serial digital transmission system for interchange of control signals, status and data between equipment internal to the aircraft (or other vehicle). The basic multiplexing technique is Time Division Multiplexing (TDM) with the information coded in 20-bit (16-bit data) words. The transmitted waveform is biphase operating at a bit rate of 1.0 megabit per second. Transmissions are bi-directional on a twisted pair shielded cable. The requirements for a bus monitor unit which interfaces with the data bus for acquisition and processing of information are described. The design for a Programmable Bus Monitor (PBM) is detailed. The PBM provides a highly flexible and effective interface between the MIL-STD-1553 data bus and an advanced digital flight test system.
    • A MODULAR APPROACH TO DATA ACQUISITION SYSTEMS

      Stevens, Walter H.; Ryan, John J.; AYDIN VECTOR Division (International Foundation for Telemetering, 1982-09)
      A description of a unique approach for construction of modular data acquisition systems using a family of standard thick film hybrid circuits. Each module is described in terms of its universal function and examples of various system constructions are explained. Demonstrating the advantages of this approach in offering minimum size, weight, and high reliability, with resonable cost for various program applications.
    • FDM-FM COCHANNEL INTERFERENCE IDENTIFICATION SYSTEM

      Chang, Horen; Alvarez, Richard; Lee, Wilfred; Niwa, Kunihiko; Rieger, Frederic J.; Stanford Telecommunications, Inc.; International Telecommunications Satellite Organization; Comsat Laboratories (International Foundation for Telemetering, 1982-09)
      A prototype interference identification system has been developed to detect and identify interfering FDM-FM carriers originating within the INTELSAT* system. Interfering carriers are identified by distinctive code (signature) modulation of the energy-dispersal waveform of each FDM-FM carrier. Identification presently is accomplished within 10 minutes for ratios of interfering carrier power to noise power down to -2 dB, and for ratios of interfering carrier power to desired carrier power down to -17 dB. Possible improvements are discussed for more rapid identification.
    • A DATA MEMORY SYSTEM FOR A SEAFLOOR EARTHQUAKE MEASURING INSTRUMENT

      Ryerson, D. E.; Lopez, A. A.; Sandia National Laboratories (International Foundation for Telemetering, 1982-09)
      A Seafloor Earthquake Measurement System for measuring strong motion seismic data has been developed and tested by Sandia National Laboratories as part of the Department of Energy Offshore Instrumentation Program. The system’s function is to gather data for the design and regulation of offshore structures such as oil platforms and pipelines. The seafloor package is a self-contained unit capable of operating unattended for up to one year with data readout on command via an underwater acoustic telemetry system. One of the problems with such a system is the large memory required to store seismic data. This memory also must consume very little power to conserve battery life. To meet these conditions a combination low-power CMOS buffer memory and a one-million-bit magnetic bubble main memory with switched power was developed. This paper describes these memories and how they are controlled by a microprocessor to save the “best” data since the last data readout.
    • THE APPLICATION OF A BUBBLE MEMORY TO A BALLOON-BORNE DATA SYSTEM

      Corlis, N. E.; Hauser, G. C.; Sandia National Laboratories (International Foundation for Telemetering, 1982-09)
      This paper describes an eight megabit bubble memory used as a mass memory storage device on a high altitude helium filled balloon flight package. The balloon flight designated as Gamma Ray VI, a coordinated effort of Sandia National Laboratories and Bell Laboratories, was conducted in the fall of 1981 at Alice Springs, Australia. Eight onemegabit Intel bubble modules were mounted on a custom designed multilayer printed wire board to maximize the memory in the available space. A microprocessor based data interface was designed to test and control the bubble memory. The selection of bubble memory modules for this application, the design considerations of the bubble printed wire board and the microprocessor interface are discussed. The flight test and results of Gamma Ray VI are described. Future developments and applications are briefly presented.
    • INVESTIGATION OF FOUR-LEVEL PCM/FM FOR SPECTRUM CONSERVATION

      Cox, Timothy F.; Nichols, Myron H.; Naval Weapons Center (International Foundation for Telemetering, 1982-09)
      Four-level PCM/FM is investigated for reduced spectrum occupancy relative to binary PCM/FM. The spectrum occupancy can be reduced to 65% of binary PCM/FM at a carrier power cost of 4dB, to 58% at a carrier power cost of 7.6dB and to 50% at a carrier power cost of 10.2dB. This performance was achieved using a range type telemetry receiver. Spectra, waveforms, circuit details and BER characteristics are given.
    • CARRIER-DETECTOR EXTENDS ACQUISITION RANGE OF BPSK

      Chu, Peter; DECOM SYSTEMS, INC. (International Foundation for Telemetering, 1982-09)
      The capture and tracking range of a Costas type BPSK (QPSK) demodulator is limited by its loop bandwidth, which is determined by the synchronization threshold at different Signal-to-Noise Ratio. A frequency locked scheme, which consists of a carrier detector and digital control network, has been developed to work in parallel with the Costas loop, so the BPSK (QPSK) demodulator would be automatically led to its pull-in range at low Signal-to-Noise Ratio. The probabilities of false dismissal for signal and false alarm signal absent are analyzed.
    • SOFTWARE PROCESSING FOR THE REAL TIME DATA ACQUISITION SYSTEM (RDAPS)

      Tucher, Tommy N.; Hutchinson, Michael P.; Edwards Air Force Base; Sangamo Weston, Inc. (International Foundation for Telemetering, 1982-09)
    • A TELEMETRY SYSTEM USING WALSH FUNCTIONS WITH IMPROVEMENTS IN ACCURACY

      Feng, Ju; Beijing Institute of Aeronautics and Astronautics (International Foundation for Telemetering, 1982-09)
      A telemetry system based on Walsh functions has been developed since 1980.[1.2] The systerm is called sequency division multiplex, or SDM. A prototype of the system hss been assembled and a lot of laboratory tests are also made in recent 2 or 3 years. Of course, in order to put this system into real use, some practical problems still remain to be solved. In this paper the system design measures taken to improve the accuracy and some new a snchronization methods we adopted are described. Since the choice of subcarriers is very important in designing a telemetry system, a table of recommended sequence values of the walsh functions for subcarriers of the telemetry system is presented. Since the vibration signal in high frequency band is produced in many cases, it is necessary to build a system which can measure this signal. The frequency response of each channel is 2000 Hz , it will have wide applications in industrial automation.
    • LIKELIHOOD RECEIVER FOR FH-MFSK MOBILE RADIO*

      Viswanathan, R.; S.C. Gupta; Southern Methodist University (International Foundation for Telemetering, 1982-09)
      We investigate the performance of a likelihood receiver for the detection of frequency hopped multilevel frequency shift keyed signals (FH-MFSK) to a mobile user operating in a multi user environment. The analysis assumes synchronous transmission from base to mobiles operating in an isolated cell-cellular system and a simplified mobile radio channel. The likelihood receiver attempts to discriminate spurious rows of the decoded matrix of a user, which consists of samples from an exponential-mixture, from the correct row, which consists of samples from a simple exponential density, by computing the log-likelihood statistic for each row. It declares the row possessing the minimum value as the correct row, corresponding to the word transmitted to the user. An approximate analysis of the probability of bit error of this receiver by three means, viz. (i) large sample approximation (ii) simple Chernoff bound and (iii) Chernoff bound with central limit theorem, reveals that the likelihood receiver is only marginally superior to a hard limited combining receiver.
    • SPACE SHUTTLE PAYLOAD INTERROGATOR

      Zelon, Michael; Space Transportation & Systems Group Rockwell International (International Foundation for Telemetering, 1982-09)
      The payload interrogator (PI) for communication between the orbiter and detached DOD/NASA payloads is described. Salient features of the PI are discussed, including its capabilities and limitations. For compatible operation in the orbiter’s electromagnetic environment, the PI is equipped with a dual triplexer assembly. A limiter diode circuitry allows the PI to be safely exposed to high effective isotropic radiated power (EIRP) payloads at close range. A dual conversion PM short-loop receiver has a sufficient dynamic range for undistorted reception of near and distant payload signals. The PI acquires signals from compatible transponders within ±112 kHz of its center frequency. The center frequency can be set at 125-kHz steps for the spaceflight tracking and data network (STDN), 370 kHz for the deep space network (DSN), and 5 MHz for the space satellite control facility (SCF). The PI has falselock- on protection capability to accommodate reliable acquisition of standard NASA and DOD payload transponders. The wideband phase detector demodulates baseband information, and by the use of AGC, provides three independent constant-level data outputs. Each of the 861 frequency channels is generated instantaneously by the receiver and transmitter synthesizers. The PM-modulated RF carrier transfers command information to the detached payloads. The RF output power is adjustable to assure reliable communication with payloads of various sensitivities (G/T). A wide and narrow carrier sweep capability is provided to accommodate any frequency uncertainty of payloads. The transmitter has an ON-OFF modulation control to avoid false-lock-on problems. The PSP command input modulation index is fixed, while the modulation index for the PS is a function of the input voltage. The PI receiver’s complementary transmit channels are spaced 115 kHz for STDN, 341 kHz for DSN, and 4 MHz for SCF. The PI is compatible with the orbiter’s configuration control equipment—GCIL, the PSP and PS for I/O data transfer, the Ku-band subsystem for “bent pipe” baseband telemetry transmission to ground, the MDM for the PI’s telemetry transfer, and the RHCP/LHCP antenna subsystem. Overall PI capabilities and limitations for communication with unique payloads are also presented.
    • CONSOLIDATED SPACE OPERATIONS CENTER (CSOC)

      Smith, Douglas L.; Launch and Control Systems Acquisition Space Command Los Angeles AFS (International Foundation for Telemetering, 1982-09)
      The Consolidated Space Operations Center (CSOC) will fulfill the nation’s need for an endurable and secure facility for the command and control of DOD Shuttle and satellite missions. For greater endurance, economy, and efficiency, it capitalizes on technical opportunities to integrate satellite-control capabilities. Additionally, CSOC functionally internets military and civilian resources to support military space operations.
    • NASA DEEP SPACE NETWORK OPERATIONS ORGANIZATION

      Chafin, Roy L.; Jet Propulsion Laboratory California Institute of Technology (International Foundation for Telemetering, 1982-09)