• IMPACT OF CHANNEL ERRORS ON DATA COMPRESSION

      Gerardi, F. R.; Omura, J.; The Aerospace Corporation; University of California (International Foundation for Telemetering, 1982-09)
      This paper will present the relationship between the distortion of compressed data to the bit error rate on the channel. In most studies of data compression techniques, the communication channel is assumed to be error-free. Under this assumption, smaller distortions are generally achieved with more complex data compression techniques. Likewise, from the mathematical theory of data compression known as rate distortion theory, it is known that the minimum possible average distortion of data compression systems can be approached as the complexity or size of the source code increases.
    • The Impact of Phase Noise in Digital Satellite Communications

      Cuccia, C. Louis; Ford Aerospace and Communications Corporation (International Foundation for Telemetering, 1982-09)
      Many military and commercial satellite communication links are being used which utilize standard or staggered QPSK. At bit rates below one megabit, these links operate in environments which produce two types of impairments–continuous and random--which determine the final bit error rate and data throughput. This paper will discuss the impact of random phase jitter which is a major impairment which can be contributed at every point in the link. This phase jitter can cause significant phase and timing errors at the receiver output and can even lead to drop-outs of key terminal equipments. The various sources of phase jitter will be discussed and related to system performance. Particular emphasis will be made of the contributions of scintillation and random atmospheric effects and by equipment malfunctions to phase noise which can cause not only periods of increase in bit and timing error, but also clock slippage and I/C reversal which can cause decoders description and demultiplexers to become inoperative. This paper will also include considerations of cochannel and adjacent channel interference on phase jitter.
    • International Telemetering Conference Proceedings, Volume 18 (1982)

      Unknown author (International Foundation for Telemetering, 1982-09)
    • 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.
    • 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.
    • KU-BAND COMMUNICATION SUBSYSTEM

      Jarett, Keith; Hughes Aircraft Company (International Foundation for Telemetering, 1982-09)
      The Ku-Band subsystem for NASA’s Space Shuttle Orbiter is a combined radar and communications system that provides either radar-aided rendezvous capability or high-rate two-way communications via a synchronous-orbit TDRS relay satellite. This paper describes the architecture of the Ku-Band system and focuses on several unique aspects of the design. Communication capabilities are described in detail.
    • 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.
    • THE MAN-MACHINE INTERFACE IN COMPUTERIZED TELEMETRY SYSTEMS

      Reber, Tilo F.; New Mexico State University (International Foundation for Telemetering, 1982-09)
      This paper concerns itself with the interface between men and computerized telemetry systems. This interface relates to the operation, planning, and implementation of setup and data processing functions. One of the major problems in operating a telemetry system is the programming of equipment parameters. This programming is often done by skilled “real-time” software personnel. This is both a costly and restrictive approach. The author has developed a “friendly” menu-driven, operator interactive, approach to solving these problems. The man-machine interface consists of software developed to present telemetry system options to an operator for selection. These options are displayed via the operator’s CRT. These displays are menus and they are formatted to display operator options in telemetry language. The object is to allow normal telemetry operators to configure the equipment setup and the data processing parameters. Once the configuration has been defined, the system can be configured quickly and precisely by the computer software. Changes to a setup or data processing configuration can be made by telemetry operators without the help of full-time programmers.
    • 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.
    • MODULAR TELEMETRY SOFTWARE FOR REAL-TIME APPLICATIONS

      STROCK, O.J.; Data Systems Division Sangamo Weston (International Foundation for Telemetering, 1982-09)
      A modular software system, operating in conjunction with unique direct-memory-access hardware modules, provides control of real-time high-speed telemetry data entry, storage, processing, and display in any of a family of small general purpose minicomputers. The software operates with engineer-language commands.
    • A MULTI-USER TELEMETRY PROCESSING ARCHITECTURE

      Michaud, Colonel Normand; Hollander, Sidney; Hq Air Force Satellite Control Facility (AFSCF); The Aerospace Corporation (International Foundation for Telemetering, 1982-09)
      This paper updates the previous work,¹ which described the overall telemetry and data processing capabilities of the Data System Modernization (DSM) system being developed at the Air Force Satellite Control Facility (AFSCF). Having passed the System Critical Design Review milestone, the DSM program is proceeding with the design and implementation of various elements which support both the real-time routing, processing, storage, and display of satellite telemetry data, as well as the off-line recall of raw or processed telemetry data for trend analysis and satellite operations planning. A Data Distribution Element routes data received from 13 Remote Tracking Station (RTS) antennas and other sources to dedicated telemetry processing elements located within eight Satellite Test Center (STC) Mission Control Complexes (MCCs), a Range Control Complex (RCC), and the System Development and Test Laboratory (STDL). Two types of telemetry preprocessing elements are provided: one for processing telemetry data of rates less than 32 kilobits per second (or for processing selected measurands from telemetry data of rates up to 1.024 megabits per second), and the other for processing high-rate telemetry up to 5 megabits per second. Computer programs executing within one of two large mainframe computers and a Telemetry Contact Support Equipment Group in each MCC selectively decommutate, compress, calibrate, and store the telemetry data. Once processed, the data is formatted into unique, user-defined displays for real-time or post-contact analysis. Interfaces are also provided to satellite commanding routines for the authentication or verification of commands that have been transmitted to the satellite during the contact. Additional computer programs provide the capability to extract designated measurands from the processed telemetry history files, and format them, into messages for near realtime transmission to users remotely located from the STC. A capability is also provided to interface future telemetry preprocessing equipment, such as that required to support multiple scientific payloads aboard the Space Shuttle.
    • MULTIPLEXING HIGH SPEED PCM DATA WITH PREPROCESSORS

      Willis, James; New Mexico State University (International Foundation for Telemetering, 1982-09)
      This paper deals with the use of preprocessors to reduce loading on real-time computers. The problem of multiplexing large amounts of data, exceeding the processing capabilities of most large-scale, real-time computers is discussed in detail. Implementation of hardware solutions to multiple Pulse Code Modulation (PCM) link multiplexing is dealt with. Use of firmware algorithms to reduce preprocessor front-end loading, as well as through-put reduction is discussed. The paper covers the different techniques used to take advantage of modern firmware preprocessor/multiplexers to select data for real-time computer processing.
    • MX INSTRUMENTATION MULTIPLEXER SET

      Tinsley, Harold D.; SCI Systems, Inc. (International Foundation for Telemetering, 1982-09)
      The MX Instrumentation Multiplexer Set is used to acquire data during test flights of the MX Missile. The Multiplexer Set consists of a Multiplexer Programmer Controller Unit (MU), from 2 to 32 Remote Multiplexer Units (RU’s), and any number of Power Supply Verifier Units (PSV’S). The primary purpose of the MU is to operate as the programmable system controller, acquire local data inputs, and format this data along with data from the RU’s in a PCM Output. The RU’s interface to the MU via Instruction and Reply Data Buses providing remote data acquisition. The PSV’s provide an accurate stimulus voltage to the analog sources along with a control to offset the analog signal for test verification. Thirty-one of the possible 32 RU’s connect to the MU by two pairs of vehicle data buses, while the remaining RU is connected via the umbilical data bus. This ground resident RU is identical to the flight RU’s, but its functional requirement is quite different as it is primarily used to load and verify MU programs. Each of the vehicle data buses can be up to 130 feet in length with a 250 foot length allowed for the umbilical bus. An ideal terminated bus is not feasible in the MX application since the bus configuration changes as the missile stages. Staging will produce opens or shorts on the cable; to insure proper operation of all remaining RU’s on the bus, the interface isolation transformer incorporates both voltage and current windings to provide maximum secondary signal level with minimum reflection distortion. The data bus operates at 3.2 MHz using a Manchester II coded signal. The MU can sample 160 local differential analog channels that are programmable in gain, off-set, and to a maximum rate of 170,665 samples per second. A flexible grouping of 8 discrete inputs from the 96 discrete channels is programmable to a rate of 51,200 samples per second. The MU can also access data from four serial digital channels and provide outputs on eight command channels. During pre-flight the commands can be ground initiated, and following launch they can be time event programmed as well as being programmed repetitive in either mode. The PCM rate is 1.6 Mbps and the MU stores five in-flight selectable formats in a 4096 words by 16 bits CMOS RAM memory. Each RU can access 28 analog and 8 discrete channels, and the RU can control two command and six verification channels. The PSV does not interface to the data bus; it is controlled via a MU or RU command channel. The system can be externally synchronized or operated from an internal clock with a graceful transfer to eliminate data loss. Small size, light weight, low power and high reliability are primary characteristics of the system. Built-in monitors and fully automated computer controlled test equipment provide rapid and extreme parameter testing with a high degree of fault isolation.
    • MX MISSILE IN-FLIGHT VIBRATION DATA PROCESSING

      Baker, George; Martin Marietta Corporation (International Foundation for Telemetering, 1982-09)
      The quantity of measurements and broad frequency spectrum of interest for dynamic measurements required to support the development phase of the MX Missile, in conjunction with a limited downlink telemetry bandwidth, necessitated a unique vibration measurement system. This was accomplished by on-board vibration data processing comprising a sensor system (transducer/ low noise cable/charge amplifier) and a multichannel digital Vibration Data Processor (VDP). The processor is a 1/3 octave frequency band analyzer, employing digital filter circuitry covering 22 bands over a frequency range from 14 Hz to 2245 Hz, providing an output that represents the energy(G²) per band/time interval. A Master Data Control Unit (MU) controls the VDP operation via a full duplex data bus. This paper will describe the sensor system, with its designed in-post installation test/verification features and the capabilities and design features of the VDP. Processor characteristics such as the self-test operation whereby all 1/3 octave analysis bands are verified, the ability to meet a 60 dB dynamic range, the indivudual instructions code capability along with other features will be presented. The most important facet of this onboard processing allows a downlink data bandwidth conservation ranging up to 184:1 which is compatible with the digital telemetering system.
    • 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.
    • NASA DEEP SPACE NETWORK OPERATIONS ORGANIZATION

      Chafin, Roy L.; Jet Propulsion Laboratory California Institute of Technology (International Foundation for Telemetering, 1982-09)
    • NASA DEEP SPACE NETWORK OPERATIONS PLANNING AND PREPARATION

      Jensen, W. N.; Jet Propulsion Laboratory California Institute of Technology (International Foundation for Telemetering, 1982-09)
      The first contact that a project or user has with NASA Deep Space Network (DSN) Operations is with the Operations Planning Group. This group establishes an early interface with the user’s planning organization to educate the user on DSN capabilities and limitations. It negotiates and documents DSN support commitments to provide a firm foundation for developing the project support plans. The group develops plans and schedules to prepare the network for project support. Part of this activity is to monitor and evaluate the testing and training required in preparation of mission support. The DSN Operations Planning Group provides a team of one or two individuals dedicated to each user or project depending on the magnitude of the coordination activity. This team works through the planning and preparation activity and continues to support the project after the spacecraft launch to the end of the mission. The team provides a coordinating role after launch. It also provides planning and preparation for specific events such as planetary encounters.
    • NASA DEEP SPACE NETWORK OPERATIONS SCHEDULING

      Enari, Dennis M.; Jet Propulsion Laboratory California Institute of Technology (International Foundation for Telemetering, 1982-09)
      Network Operations Scheduling provides the scheduling management for allocating the NASA Deep Space Network resources to support flight projects and other authorized users. As a part of Network Control Center Operations, it is the task of Network Operations Scheduling to forecast, detect conflicts, support conflict resolution and schedule the allocation of the network. The products of scheduling provide management and users of the network with information that will give them visibility concerning network loading, mission support and facility utilization. Subsequent management decisions based on this information concern advanced Fiscal budgeting and station shift staffing. The structure of the scheduling system provides an orderly advancement of general user requirements during the early stages of planning to an expanded detailed set of requirements at the final stage of planning.
    • NASA DEEP SPACE NETWORK PERFORMANCE ANALYSIS

      Bartok, Carol DiNolfo; Jet Propulsion Laboratory California Institute of Technology (International Foundation for Telemetering, 1982-09)
      Network performance analysis is an essential element in the operation of the NASA Deep Space Network. The primary function of the Deep Space Network is to support the communication, radio navigation and radio science needs of the flight project users. As a part of Network Control Center Operations, it is the task of the Performance Analysis Group to provide the Network with the analysis support required to assure that actual Network performance meets or exceeds committed levels throughout the mission. The Performance Analysis Group provides time-critical monitoring and analysis for the Tracking, Telemetry and Command Systems of the Deep Space Network. The group is organized into units that are specialized to provide the functional requirements of each system. It provides failure analysis to determine causes of Network failures and data outages, as well as providing technical assistance to the operations organization for recovery from failures. It generates the predictions used to point the antennas, acquire the radio frequency, and to validate the monitored Network performance. Also, it provides technical interfaces with the user projects as required for the smooth running of the operation. As a result of this specialized expertise, complex and time-critical problems that arise receive an immediate decision-making response.