• SOFTWARE SUPPORT FOR A STORED PROGRAM PCM DECOMMUTATOR

      Peterson, Dwight M.; Fleet Analysis Center (International Foundation for Telemetering, 1982-09)
      Telemetered data generated by missile systems has become increasingly complex with the inclusion of asynchronous data streams, variable word lengths, and discrete encoding. The display of this data for analysis purposes requires sophisticated equipment, usually designed with a programmable architecture. This paper describes software support that was developed for a stored program PCM decommutator. The software includes a cross assembler and supports downline loading of the decommutator from a host computer.
    • Telemetering Standards Coordination Commitee

      Jennings, Vernon A. (International Foundation for Telemetering, 1982-09)
    • 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.
    • PRESAMPLING FILTERING, SAMPLING AND QUANTIZATION EFFECTS ON THE DIGITAL MATCHED FILTER PERFORMANCE

      Chang, Horen; Stanford Telecommunications, Inc. (International Foundation for Telemetering, 1982-09)
      Due to the increased capability and reduced cost of digital devices, there has recently been a growing trend to digitize the matched-filtering data detector in the receiver. Comparing with an idealized integrate-and-dump analog matched filter, the digital matched filter (DMF) requires more Eb /No in order to achieve the same bit error rate performance because of the presampling filtering, sampling, and quantization effects. This paper analyzes the performance degradation resulting, separately and jointly, from these three effects. Quantitative results are provided for commonly chosen sets of design parameters. For a given performance degradation budget and complexity limitation, these results could be applied to choose the optimum DMF design parameters including the presampling filter bandwidth, the sampling rate, the number of quantization bits, and the spacing between adjacent quantization levels.
    • PROCESSOR TECHNOLOGY OFFERS UNREALIZED FLEXIBILITY IN TOMORROW’S TELEMETRY GROUND STATIONS

      THOM, GARY A.; AYDIN MONITOR SYSTEMS (International Foundation for Telemetering, 1982-09)
      Today’s state of the art in semiconductor technology coupled with innovative computer architecture techniques can provide tomorrow’s telemetry industry with advanced ground station capabilities. Computer systems have traditionally been used to process all of the telemetry data. As data transmission speeds increase, the computer system can no longer handle real time processing so preprocessors are being used to handle the additional computational requirements. An alternative approach is to embed special purpose processors into applicable elements of the front-end equipment. These processors can be optimized for the function they are to perform, which prevents under utilization of processing power and enhances the flexibility and performance of the front-end element. These special purpose processors take up little real estate when implemented with todays LSI and VLSI semiconductors. The modules which are ideally suited for this type of technology are serial data correlators, decommutators, real time data correction, engineering units conversion, quick look display, data simulation and many special application modules. These processing elements provide the building blocks for a very powerful, cost effective family of modular telemetry and communications products for the 80’s and beyond.
    • 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.
    • AUTOMATIC ADDRESSING OF TELEMETRY CHANNELS

      Lucero, L. A.; Sandia National Laboratories (International Foundation for Telemetering, 1982-09)
      To simplify telemetry software development, a design that elminates the use of software instructions to address telemetry channels is being implemented in our telemetry systems. By using the DMA function of the RCA 1802 microprocessor, once initialized, addressing of telemetry channels is automatic, requiring no software. In this report, the automatic addressing scheme is compared with an earlier technique that uses software to address telemetry channels. In comparison, the automatic addressing scheme effectively increases the software capability of the microprocessor, simplifies telemetry dataset encoding, eases data set changes, and may decrease the electronic hardware count. The software addressing technique uses at least three instructions to address each channel. The automatic addressing technique requires no software instructions. Instead, addressing is performed using a direct memory access cycle stealing technique. Application of an early version of this addressing scheme opened up the capability to execute 400 more microprocessor instructions than could be executed using the software addressing scheme. The present version of the automatic addressing scheme uses a section of PROM reserved for telemetry channel addresses. Encoding for a dataset is accomplished by programming the PROM with channel addresses in the order they are to be monitored. Software for one of our telemetry units was written using the software addressing scheme, then rewritten using the automatic addressing scheme. While 1000 bytes of memory were required by the software addressing scheme, the automatic addressing scheme required only 396 bytes. A number of prototypes using AATC have been built and tested in a telemetry lab unit. All have worked successfully.
    • TELEMETRY RECORDING AND REDUCTION EQUIPMENT FOR SHIPBOARD SUPPORT OF MISSILE EXERCISES

      Daniel, Jack T.; Jones, Gary P.; E-Systems Inc., ECI Division (International Foundation for Telemetering, 1982-09)
      Evolving growth in Navy ship-to-air missile design has resulted in a need for larger quantities of telemetry information with increasing emphasis on digital telemetry. This has inherently led to the requirement for telemetry processing equipment that is adaptable to these changing missile telemetry data formats. The design for the Telemetry Recording and Reduction Equipment (TRRE), that incorporates today’s technology into a compact, realtime analysis tool for shipboard use, is presented in this paper. The TRRE was designed to process both the Pulse Amplitude Modulation (PAM) telemetry data formats of existing missile designs and the Pulse Code Modulation (PCM) data formats of evolving missile designs. The TRRE design minimizes the required operator interace through preprogrammed telemeter formats and programmable decommutation tables. A microprocessor is utilized in the design to program the decommutation hardware configuration.
    • DISCUSSION OF CLASSICAL AND PUBLIC KEY CRYPTOGRAPHY

      Hershey, John E.; Institute for Telecommunication Sciences (International Foundation for Telemetering, 1982-09)
      Classical and public key cryptography for communications privacy are discussed regarding their relative implementation complexity and overall applicability.
    • AIR FORCE SATELLITE CONTROL FACILITY (AFSCF) SUPPORT OF THE SPACE TRANSPORTATION SYSTEM (STS) ORBITAL FLIGHT TEST PROGRAM

      McBride, Michael L.; Applied Research, Inc. (International Foundation for Telemetering, 1982-09)
      The-AFSCF is tasked with providing support to NASA for the initial series of STS flights known as Orbital Flight Test (OFT) missions. This support requires modifications to the AFSCF data and voice communication elements at the remote tracking stations and the Satellite Test Center to implement interfaces between the AFSCF and the NASA Goddard Space Flight Center (GSFC), and between the AFSCF and Space Shuttle Orbiter Vehicle itself. Data communications involves the exchange of telemetry, tracking, and command data; while voice interfaces involve air-to-ground as well as ground-based support communications networks. The modified AFSCF configuration provides a base from which expanded Orbiter vehicle and payload support may be developed. This paper identifies the modifications implemented within the AFSCF to provide STS OFT support and traces the flow of voice and data communications throughout the STS-AFSCF-GSFC network. Potential candidate support configurations to provide expanded Orbiter and payload support are also identified.
    • THE TAPE RECORDER SHUTDOWN ALARM

      Hahn, Jacob C.; Rockwell International (International Foundation for Telemetering, 1982-09)
      Data from the Space Shuttle is recorded on magnetic tape during manufacture, during pre-flight tests and during flight. Thus a permanent record is obtained for all tests. When a tape recorder suddenly stops before the end of its run, some data will not be recorded. Tape recorders run silently and make no sound when they stop. A tape recorder that is not running is easily observed, but constant visual monitoring is impractical. Yet it is important that personnel become aware of the problem at once. An audio alarm that sounds when a tape recorder stops before the end of its run will alert personnel. An alarm in use at Rockwell’s Flight Systems Laboratories not only sounds when a tape recorder stops before it is supposed to, but it turns on a standby recorder in less than two seconds.
    • DIGITAL TV TRI-STATE DELTA MODULATION SYSTEM FOR SPACE SHUTTLE KU-BAND DOWNLINK

      Udalov, Sergei; Huth, Gaylord K.; Batson, Bartus H.; Roberts, Donald; Axiomatix Corp.; NASA/Johnson Space Center (International Foundation for Telemetering, 1982-09)
      The anticipated requirements for Shuttle Orbiter Ku-band downlink communication include the transmission of a digital video signal which, in addition to accommodating the black-and-white TV pictures, must also be able to relay to the ground the color TV information encoded in either field-sequential or NTSC color formats. Furthermore, at the expense of additional onboard hardware and increased bandwidth due to the digitization process, the picture privacy feature can be provided for the downlink. Thus, an objective for the future Space Shuttle TV equipment is the development of a digitization technique which is not only compatible with data rates in the range of 20 -30 Mbps, but also provides good quality pictures. This paper desribes a tri-state delta modulation/demodulation (TSDM) technique which is a good compromise between implementation complexity and performance. The salient feature of TSDM is that it provides for efficient run-length encoding of constant-intensity segments of a TV picture. Axiomatix has developed a hardware implementation of a highspeed TSDM transmitter and receiver for black-and-white TV or field-sequential color or NTSC format color. The hardware aspects of this TSDM are discussed in the paper also.
    • 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.
    • DESIGN OF A FOUR-CHANNEL, 50 MBPS, STATISTICAL MULTIPLEXER AND DEMULTIPLEXER

      O’Donnell, John T.; Digital Communications AYDIN MONITOR Systems (International Foundation for Telemetering, 1982-09)
      This paper discusses the design of a 50 Mbps Statistical Multiplexer and Demultiplexer, Model 781, manufactured by AYDIN MONITOR Systems of Fort Washington, PA. Two Model 781s connected through a 50 Mbps communications link constitute a full-duplex, 4-channel data link with a maximum aggregate throughput capability of 48 Mbps.
    • 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.
    • PERFORMANCE OPTIMIZATION OF PCM/SCO TELEMETRY SYSTEMS

      Jeske, Harold O.; Sandia National Laboratories (International Foundation for Telemetering, 1982-09)
      These hybrid TM system design procedures indicate how PCM channel performance comparable with that obtainable from an optimally designed PCM/FM transmission system may be obtained even though numerous subcarrier channels are included in the system. Optimal design goals are those that permit satisfactory telemetry system operation with a minimum of transmitted power. By careful control of the transmitter modulation levels and the use of predetection filtering during playback, a lowering of the PCM channel’s threshold, equivalent to at least quadrupling the transmitter power over conventional practices, is obtained. This report briefly discusses the design objectives of FM/FM and PCM/FM systems followed by a more detailed discussion of hybrid systems using FM subcarriers above the PCM signal on the baseband. A simplified, but comprehensive, discussion of FM sidebands is presented in the appendices to aid in understanding the limits and restrictions in this hybrid TM system design procedure.
    • AN APPLICATION OF DISTRIBUTED PROCESSING (IN THE TDRSS GROUND COMMUNICATION FAULT ISOLATION AND MONITORING SYSTEM)

      Waddell, R. L.; Utterback, H. K.; The Johns Hopkins University (International Foundation for Telemetering, 1982-09)
      A Fault Isolation and Monitoring System (FIMS) for analysis of the quality of data streams transmitted between TDRSS and NASA’s Network Control Center has been completed and installed (Version 1) in the NASA White Sands Ground Terminal. Due to the demands on the system’s central computer, it was decided that as much of the operator interaction as possible should be handled by the intelligent terminal serving as the operations control console. This paper describes the methods and protocol used to implement the operator support software required to configure the monitoring system and to display and report the results of the analysis.
    • 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.
    • 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)
    • DMSP BLOCK 5D-2 SPACECRAFT Telemetry Real-Time Analysis and Display System (TRADS)

      Allen, David L.; The Aerospace Corporation (International Foundation for Telemetering, 1982-09)