• THE EFFECT OF PREMODULATION FILTERS ON BIT ERROR RATE PERFORMANCE

      Bobrek, Pavlo; Sangamo Weston, Schlumberger (International Foundation for Telemetering, 1982-09)
      This paper examines the effect of different types of premodulation filters on the time waveshapes of PCM signals. Using a simplified model of this effect, an expression for the Probability of Error in the presence of Gausian Noise is derived and compared for systems with and without premodulation filtering. A simple single bit decision feedback detector is designed and an evaluation made of its usefulness in improving bit error rate performance using different filters in the presence of different amounts of noise.
    • THE EFFICIENT USE OF A VAX COMPUTER IN THE REAL-TIME TELEMETRY ENVIRONMENT

      Robbins, Robert B.; Data Systems Division (International Foundation for Telemetering, 1982-09)
      The use of a Digital Equipment Corporation VAX computer under the VMS operating system, in a real-time telemetry environment, brings with it many advantages. These advantages pertain to its ability to handle real-time telemetry processing in an efficient and relatively straight forward manner. The author will use the TELSET, TELDAX and TELFOR telemetry software systems as the basis for demonstrating the techniques which have allowed the real-time telemetry user to take advantage of a 32-bit, virtual addressing, architecture.
    • THE ELECTRONIC SWITCHING SPHERICAL ARRAY (ESSA) ANTENNA FOR THE EARTH RADIATION BUDGET SPACECRAFT (ERBS)

      Kudrna, Ken; Hockensmith, Richard P.; Ball Aerospace Systems Division; Goddard Space Flight Center (International Foundation for Telemetering, 1982-09)
      The ESSA is a microprocessor controlled antenna for low orbiting spacecraft for telemetry and command relay through the Tracking and Data Relay Satellite (TDRS) System. The array is a hemispherical shape which is covered with disk radiating elements. A group of radiating elements are continuously selected by the microprocessor controller to form a beam in the direction of a TDRS. A radial switching power divider uses PIN diodes to select the desired radiating elements. The antenna gain is a function of the size of the hemispherical dome. A 30-inch diameter dome is presently being built for the Earth Radiation Budget Spacecraft (ERBS). Gain of this antenna over a hemisphere is 14 dBi and polarization is left hand circular. There are 145 radiating elements with 12 being used at one time to form a beam. The ESSA subsystem weighs 74 pounds and power consumption is 20 watts. R. F. power handling capability is 30 watts. The S-Band radiating elements have a 10 percent bandwidth which allows simultaneous transmission and reception.
    • ELECTRONICALLY STEERABLE SPHERICAL ARRAY CAPABILITIES AND INTERFACES

      Taylor, Taliaferro H.; Ball Aerospace Systems Division (International Foundation for Telemetering, 1982-09)
      For antenna applications which require gains of 7 to 23 dBic over very large solid angle coverage regions, the Electronically Steerable Spherical Array (ESSA) is an antenna which has significant benefits. This paper describes these benefits along with the ESSA’s key performance parameters and its electrical and mechanical interfaces. As extensions of the basic ESSA design, this paper also describes alternate configurations which allow multiple beam operation and integrated packaging of RF electronics. Basically a simple antenna, the ESSA forms its beams by selecting N elements which point in the desired direction. Selection of these elements is performed by a multipole PIN diode switch. This switch sums together the N desired elements from the M elements located on the ESSA’s spherical surface upon receipt of the appropriate commands from the ESSA’s dedicated microprocessor. The ESSA may be either Phase Compensated, or Non-Phase Compensated. In the Phase Compensated ESSA, a 1 or 2 bit phase shifter is used to correct the spherical phase front produced by the array shape. That correction results in higher gain. The most important ESSA benefits are its characteristics of constant phase and gain which are independent of beam pointing angle. These characteristics free the system from the gain and phase perturbations caused by other types of antennas. As a mature technology, the ESSA has been successfully tested with the NASA standard transponder and is presently being fabricated as a 14 dBic gain protoflight unit for a NASA-Goddard Space Flight Center program.
    • 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.
    • GALILEO JUPITER PROBE ATMOSPHERE STRUCTURE INSTRUMENT

      Padilla, Jose R.; Martin Marietta Corporation (International Foundation for Telemetering, 1982-09)
      More will be learned about planet Jupiter in the 45-minute Jupiter Probe mission than has been learned in nearly 500 years.
    • GLOBAL DATA COLLECTION VIA THE INTERNATIONAL TELEPHONE NETWORK

      KYRIAXOPOULOS, NICHOLAS; Department of Electrical Engineering and Computer Science The George Washington University (International Foundation for Telemetering, 1982-09)
      An experimental secure, global, data collection system for possible use in international nuclear safeguards has been built and it is undergoing testing and evaluation. The system known by the acronym RECOVER (REmote COntinual VERification), is designed to monitor the operating status of containment and surveillance instrumentation used in nuclear facilities subject to international safeguards. The uniqueness of the design is based on the intended use of the system by an international organization operating as a guest of national entities, with the sensors residing in host facilities while the data collection remains under the control of the international organization. This paper describes the impact of a unique set of technical, economic, political and operational constraints on all aspects of the system design, and it presents the results of an internationally conducted test of the data acquisition features of the system.
    • HUMAN FACTORS IN OPERATIONS DESIGN

      Chafin, Roy L.; Jet Propulsion Laboratory California Institute of Technology (International Foundation for Telemetering, 1982-09)
      There are several underlying factors in the design of an operations organization to control a high technology spacecraft tracking system. The first is the princple of differentiation and integration. The multitude of tasks must be divided so that each individual or team can accomplish assignments without being overloaded. Then, the efforts of all the elements in the organization must be integrated for a consistent attack on the problem of tracking a spacecraft. The differentiation tends to be primarily along technical or functional lines, and by time span, but there are other considerations. The integration is provided by the organization’s coordination and control elements. Operating positions can be designed to be procedurally operated, knowledge operated, or somewhere in-between. “Procedurally operated” means that the operator follows a strict procedure. He does not need to know how the system works, only which procedure to follow. A “knowledge based” operating position means that the operator understands the system sufficiently well to know what to do to accomplish a task. He does not need written procedures. The selection of either procedural based or knowledge based operations influences the operator skill level required, the organization design, and the support required. The system’s uncertainty level, stability level, and complexity are examined to evaluate the level of procedural operation possible.
    • 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)

      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.