• PCM/FM+FM/FM Design Parameters for Telemetering Systems

      Carden, Frank; Moser, Juliette; New Mexico State University (International Foundation for Telemetering, 1992-10)
      In a PCM/FM+FM/FM system, the PCM data is added to the subcarriers at baseband and the composite signal is modulated onto the carrier. When the subcarrier messages are demodulated, part of the PCM signal's spectrum falls within the bandwidth of the subcarrier bandpass filters. This causes interference with the subcarrier messages, particularly those of the lower subcarrier frequencies. When designing a PCM/FM+FM/FM system, one is concerned with the placement of the subcarrier frequencies and the interference suffered by the subcarriers due to the PCM signal. This paper develops a relationship between the lowest frequency subcarrier, PCM bit rate and the resulting interference. The design procedure allows a bit rate or lowest frequency subcarrier to be selected for a specified interference ratio. The expression of the ratio is a complex integral which is reduced to a simple equation involving the system parameters.
    • A High Performance MIL-STD-1773 Data Bus

      Zheng, Li; Yu-De, Ni; Jian-Guo, Zhang; Beijing University of Aeronautics and Astronautics; Civil Aviation Institute of China; University of Parma (International Foundation for Telemetering, 1992-10)
      This paper gives detailed ideas and methods about the design and development of high performance MIL-STD-1773 airborne fiber optic data bus. To reject impulsive interference efficaciously, the large core and large numerical aperture fiber optics are adopted, as well as high- emitted power LEDs and a low noise optical receiver structure to get high signal-to-noise ratio at decision time. Two new modulation technique----digital frequency shift keying and partial tri-level Manchester are recommended, which are very attractive in the design of modern optical bus. Meanwhile, VLSI chips COM1553B are used to construct bus control interface unit, thus many advantages have been brought out.
    • Estimation of Tec and Range of EMP Source Using an Improved Ionospheric Correction Model

      Kim, Y. S.; Eng, R.; The Aerospace Corporation (International Foundation for Telemetering, 1992-10)
      An improved ionospheric delay correction model for a transionospheric electromagnetic pulse (EMP) is used for estimating the total-electron-content (TEC) profile of the path and accurate ranging of the EMP source. For a known pair of time of arrival (TOA) measurements at two frequency channels, the ionospheric TEC information is estimated using a simple numerical technique. This TEC information is then used for computing ionospheric group delay and pulse broadening effect correction to determine the free space range. The model prediction is compared with the experimental test results. The study results show that the model predictions are in good agreement with the test results.
    • An Open Software Architecture for UNIX Based Data Acquisition/Telemetry Systems

      Dawson, Daniel; Veda Systems Incorporated (International Foundation for Telemetering, 1992-10)
      Veda Systems Incorporated has recently completed the development of a completely open architecture, UNIX-based software environment for standard telemetry and more generic data acquisition applications. The new software environment operates on many state-of-the-art high-end workstations and provides a workstation independent, multiuse platform for front-end system configuration, database management, real-time graphic data display and data, logging.

      Eccles, Lee H.; Boeing Commercial Airplane Group (International Foundation for Telemetering, 1992-10)
      A family of data recorders are being developed for use by the Boeing Commercial Airplane Company in flight testing the 777 airplane. The intention is to have a family of recorders which all have the same interface to the recording and monitor systems but have vastly different data rates and capacities. At this time two recorder systems are being developed. The large recorder will be an Ampex DCRSi with a custom interface for the new data acquisition system. The small recorder will be an Exabyte Model 8500 with a similar interface to the one being used in the DCRSi. An intermediate recorder may be developed if the economics of the system show that it would be cost effective but, it is not presently under development. This paper discusses the recorders, the modifications necessary to develop the interfaces and the interfaces themselves for both the large and small recorders.
    • The Architecture and Design of Parallel Processing for Real-Time Multiplexing Telemetry Data

      Jun, Zhang; Qishan, Zhang; Beijing University of Aeronautics and Astronautics (International Foundation for Telemetering, 1992-10)
      The parallel processing technology has been widely applied to many science and engineering technical fields, also to telemetry. In particular, telemetry develops towards the trend of large capacity, high rate, several data streams and programmable formats. This sets a still higher demand on processing for real-time multilexing telemetry data. On the basis of analyzing of the characteristics of telemetry data processing (TDP), the parallel processing conception and methods are adopted, countering multiiple-channel data streams of different objects, several architectures of parallel processing for real-time multiplexing telemetry data are presented. It makes better use of the concurrency during the process of TDP and handles the telemetry information effectively in every processing level of the whole telemetering information processing system. The paper shows the property comparison of these parallel processing architectures and main features too. Experiments have indicated that it is an economical and effective method to improve the performance of telemetry information processing system by using paralle processing architecture which is based on concurrency of telemetry data processing.
    • Edwards Digital Switch System Overview

      Switzer, Earl R.; Straehley, Erwin H.; Edwards Air Force Base; Straehley Associates (International Foundation for Telemetering, 1992-10)
      The Edwards Digital Switch (EDS) is a digital communication system that provides advanced voice networking capabilities to the Edwards Test Range. The EDS is a member of a new family of all-digital switching systems that internally handle data in digital form. To accommodate analog voice and data circuits, conversions between analog and digital formats occur at the system interfaces. The EDS consists of six groups of configuration items: System-level control and monitoring is centralized in the Control and Display Subsystem. Workstations provide subsystem-level control and monitoring. The Central Switching Subsystem, as the primary interface with the range environment, provides system connectivity to radios, telephone circuits, and communications links to other facilities. It integrates the EDS with links to the Control Room Switching Subsystems. Each Control Room Switching Subsystem connects individual user stations within a Mission Control Room or other localized area. The user equipment element consists of a Subscriber Terminal Unit, Channel Expander, and interface panels for headsets, foot switches, and speakers. The Remote Radio Control Unit optimizes usage of available frequencies, allowing control of tunable radios from the Control and Display Subsystem. *The original name, Edwards Communication Switching System (ECSS) was changed to Edwards Digital Switch (EDS) in 1990. The Site Selection Unit facilitates the handover of voice communications between receiver sites when a long-range test is monitored. The system architecture is based on a central system-level control element, a central switch, multiple subsystem-level control elements, multiple subsystem switches, and end-equipment items that are interconnected through the switch network. The EDS combines multiple voice communications applications in a single system. The system is being expanded to integrate voice and data switching. Its major function is support of multiparty networked voice communications within Mission Control Rooms and between other test participants. Other voice functions are an intercom capability including both Direct Access (hot line) and Indirect Access (dial-up), subscriber loop connections to the base-level telephone exchange, and the Public Switched Network System. Digital interfaces allow integration of ciphertext data and Time Space Position Information data switching functions. A system based on the EDS design has also been installed by the Air Force at Eglin AFB. Engineering studies for systems that make use of the EDS design are currently underway by the Navy at China Lake and the Army at White Sands Missile Range. The EDS project office has actively pursued promising program management concepts such as: specifying nondevelopmental items, requiring industry standard interconnectivity and interoperability, and using a multiyear fixed-price requirements-type contract to encourage multiservice participation.
    • A High Dynamic Range Microwave Fiberoptic Link for Telemetry/Tracking Systems

      Grimes, W. Gary; Curran, Randy; Ortel Corporation; Datron Systems, Inc. (International Foundation for Telemetering, 1992-10)
      This paper presents a simple, cost-effective solution that permits the antenna in a telemetry/tracking system to be placed at distances even greater than 20 km with virtually no signal degradation. By using a wideband, microwave fiberoptic link to pass the RF telemetry and tracking signals directly, the telemetry receivers can all be installed at the operator's location. In essence, the only RF equipment that needs to be installed at the antenna site is the low maintenance fiberoptic transmitter which can be placed in a ruggedized housing at the pedestal. The actual system described herein uses a hybrid approach with some telemetry receivers at the antenna site and some remoted over the fiberoptic link. It is shown that the fiberoptic link used met and exceeded the system requirements. In addition, the design of the fiberoptic link is discussed and it is shown that the dynamic range acheivable with this fiberoptic link is considerably higher than the system requirements in this case.
    • Single Point User-Interface Software Design for Telemetry Stations

      Corbin, Brian A.; NASA (International Foundation for Telemetering, 1992-10)
      As the repetitive processes in the manufacturing community are being automated to reduce operating cost, the satellite tracking station (being for the most part a repetitive operation) can also reduce operating cost by automation. A conventional satellite tracking station requires personnel to setup, monitor, and adjust a variety of equipment, coordinate data collection, and archive collected data. By automating, the above duties in addition to managing the station can be done through a single-point user interface. This paper presents the methods used to design the user-interface software including graphical user interface (GUI) types of hardware I/O for data acquisition and control, and remote control.
    • International Telemetering Conference Proceedings, Volume 28 (1992)

      International Foundation for Telemetering, 1992-10

      Jacobsen, H. D. (International Foundation for Telemetering, 1992-10)
      Lempel-Ziv-Welch (LZW) algorithm is a popular data compaction technique that has been adopted by CCITT in its V.42bis recommendation and is often implemented in association with the V.32 standard for 9600 bps modems. It has also been implemented as Microcom Networking Protocol (MNP) Level 7, where it goes by the name of Enhanced Data Compression. LZW compacts data by encoding frequently occurring input strings with a single output symbol. The algorithm automatically generates a string dictionary for each symbol at each end of the transmission path. The amount of compaction that can be derived with the LZW algorithm varies with the type of data being transmitted and the efficiency by which table entries can be indexed. Table indexing is usually implemented by use of a hashing table. Although some manufacturers advertise a 4-to-1 gain in throughput, this seems to be an extreme case. This paper documents a implementation of the exact ZLW algorithm. The results presented in this paper are significantly less, typically on the order of 1-to-2 for ASCII text, with substantially less compaction for pre-compacted files or files containing random bit patterns. The efficiency of the LZW algorith on ASCII text is shown to be a function of dictionary size and block size. Although fewer transmitted symbols are required for larger dictionary tables, the additional bits required for the symbol index is marginally greater than the efficiency that is gained. The net effect is that dictionary sizes beyond 2K in size are increasingly less efficient for input data block sizes of 10K or more. The author concludes that the algorithm could be implemented as a direct table look-up rather than through a hashing algorithm. This would allow the LZW to be implemented with very simple firmware and with a maximum of hardware efficiency.
    • Data Rate Upgrade of the DFCS Waveform

      Walthall, David; Eglin Air Force Base (International Foundation for Telemetering, 1992-10)
      New tracking/control system requirements demand that the present DFCS/GRDCUS/MTACS data link bit rate be increased. A possible method for achieving this increase is to select two additional 31-bit chip code patterns that are orthogonal to the present chip codes, and to each other. This method will not require any more bandwidth than the present 10 MHZ used. This method suggest that each of the four chip code patterns are assigned a two bit value ie: 00, 01, 10, 11. At present, the two correlated chip codes represent data in a pulse position method. No data is contained in which of the two chip codes actually correlated. This new method suggest each of the four chip code patterns will still perform the pulse position modulation and provide two additional bits of data. These additional two bits of data will up the data rate of the link by 100 percent.

      McMahon, Michael M.; Loral Conic Inc. (International Foundation for Telemetering, 1992-10)
      Analog video telemetry links are generally realized with an FM video transmitter and an FM video receiver. Various standards specify characteristics of both the baseband video signal and the transmitted modulation characteristics. This paper summarizes and clarifies these standards so that the video/transmitter interface may be specified and correctly set up. Monochrome and color video signal levels are described. Required deviation and pre-emphasis characteristics of the transmitter are also clarified.
    • Integrated Media Technologies for Satellite Decision Support Systems

      Sutton, S. A.; Yu, C. S.; The Aerospace Corporation (International Foundation for Telemetering, 1992-10)
      Within the Aerospace industry, the operational community is facing staff reductions, reduced skill levels, and greater complexity of space assets and space missions. This combination requires that techniques be developed that more efficiently interface a human operator with a complex computer system. Operational support of complex space systems will be greatly facilitated by better presentation of information. The presentation and distribution of complex data must evolve towards formats that are easily and naturally embraced by our sensory systems. Some of the information technologies/techniques that facilitate the presentation of complex dynamic graphical data fall into a category called integrated media. The cost of implementing integrated media (IM) architectures has decreased substantially within in the past five years. While implementation costs continue to recede, the quality and value of information that can be presented using IM technologies continues to improve. Today's IM architect can select a variety of components including digital interactive video, 3D Navigable Worlds, Multimedia Authoring Systems, standardized compressors for IM data, low cost high volume storage systems, and operating system extensions for temporal data management. Together, these components form a solid foundation for the development of a variety of compelling IM architectures. Existing satellite support and mission data processing architectures typically present tabular data for assessment. Some "advanced" systems include 2D graphical projections of the data. System experts are generally trained to correlate relationships between tabular data items. The training required to "learn" these complex relationships is tedious and time consuming. This complexity impedes productivity and as space systems increase in sophistication, these techniques for data assessment are quickly becoming antiquated. The development of a prototype decision support system explores the utility of an integrated media documentation system as part of a full-featured decision support architecture for satellite operations.
    • Universal Interface Between Telemetry Processors and Chart Recorders

      Brimbal, Michel; Kelly, Fred; GOULD Inc., Test & Measurement (International Foundation for Telemetering, 1992-10)
      Chart recorders currently in use on telemetry ranges are connected to telemetry processors via a series of Digital to Analog Converters (DAC) systems. A new modular interface system receives data directly from the processor broadcast bus and distributes them to up to ten digital chart recorders. This interface is programmed from a computer to assign individual tags to each one of the display channels. This system eliminates DAC's and patch panels. It simplifies display system operation, speeds up transition from test to test and reduces maintenance costs.

      Faulstich, Raymond J.; Naval Air Warfare Center Aircraft Division (International Foundation for Telemetering, 1992-10)
      The Common Airborne Instrumentation System (CAIS) is being developed through the Department of Defense Central Test and Evaluation Investment Program (CTEIP) to support the flight test requirements of the military services into the next decade. CAIS consists of an airborne data acquisition segment and a ground based support segment. The system is designed to accommodate both the small user and the larger, more complex full scale development programs. This paper presents a program overview of CAIS from a users view.

      Bisson, Kenneth J.; Aptec Computer Systems (International Foundation for Telemetering, 1992-10)
      There are many applications that require multiple processors performing real-time tasks and communicating with each other over a common bus or memory. Aptec has developed a real-time multiprocessing system which reduces the integration effort needed in a custom designed system. The system uses commercially available Motorola 68000 series processors each running a real-time kernel. Software has been developed to extend the capabilities of the real-time kernel. This software is called Multiprocessor Services. The software allows tasks running on different processors to communicate with each other and a global shared memory. This paper describes the features of real-time multiprocessor hardware systems, and how the multiprocessor software coordinates the processors to operate as an integrated system.

      Griffin, Alan R.; Wooten, R. Stephen; Hanscom Air Force Base; CALCULEX, Inc. (International Foundation for Telemetering, 1992-10)
      The vast amount of data telemetered from space probe experiments requires careful management and tracking from initial receipt through acquisition, archiving, and distribution. This paper presents the automated system used at the Phillips Laboratory, Geophysics Directorate, for tracking telemetry data from its receipt at the facility to its distribution on various media to the research community. Features of the system include computerized databases, automated generation of media labels, automated generation of reports, and automated archiving.
    • An Object-Oriented System for Telemetry Data Management

      Tolat, Viral V.; Stanford University (International Foundation for Telemetering, 1992-10)
      In this paper we describe an object-oriented software system for realtime telemetry data management and display. The system has also been designed to be used as the primary means of data management during post-mission activities. The software system consists of three parts: the data interface library, the data format specification and the display applications. The data interface library contains a set of object definitions and procedures to provide uniform access to heterogeneous data streams. The data format specification is used by the data interface library to extract data from the raw data stream. The display applications use the data interface library to access the data and present it to the user. Currently, the interface between the data format specification and the data interface library is implemented procedurally and is modeled after a device driver. Each format is assigned a unique id and then accessed via that id. A data stream may be accessed by any number of different format specifications. A future implementation will separate the data format specification into a separate process with a message or RPC based interface. Therefore the data may be kept on remote systems and accessed in a transparent fashion. In addition, this model will support operation in distributed heterogeneous computing environments. This system handles multiple simultaneous data streams and applications can access data from different streams relatively transparently. This is possible since data variables (objects) to be displayed are specified by a syntax that contains the specification of both the data streams and the format to use. In addition, the concept of a primary stream is introduced to allow the user to scroll through one data stream and have the other streams follow. Synchronization between streams is based on time information in the data streams. Several applications have been written including various stripchart displays a tabular display and some other custom displays. A data analysis application similar to the UNIX program "awk" is currently under development. It will provide the user with the ability to extract data, i.e., report generation, for display or further analysis in an object-oriented manner.
    • The Shipboard Antenna Tracking System of Telemetry

      Quan-Hui, Gao; Beijing Research Institute of Telemetry (International Foundation for Telemetering, 1992-10)
      This paper describes a C-band auto-tracking receiving system on shipboard which is used in satellite telemetry. The system consists of receiving antenna, wideband feed, antenna pedestal, telemetry/tracking receiver antenna controller and computer console. Its characteristics are as follow: Single Channel Single Pulse Tracking Feed, 2. 5m Antenna Diameter, 500MHz BW, LHCP and RHCP Dual - Channel Polarization Diversity Receiving. The servo system uses rate - gyros as stabilized element being based on the micro - processor to realize the digital servo control. Computer console performs the status monitoring and management to the whole system. The system design, the main system specification and important test results are given.