• 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.
    • Managing Telemetry Information in the New Era of Test and Evaluation

      Gardner, Lee S.; Hoaglund, Catharine M.; Painter, Darcy S.; Air Force Flight Test Center (International Foundation for Telemetering, 1992-10)
      Terms like efficiency, quick response, and interoperability are becoming the bywords of the test and evaluation (T&E) community as the Defense Department tightens its corporate belt [1]. These changes mark the end of an era of manual processes and duplication of effort and the beginning of an era of cooperation, standards, and Total Quality Management (TQM). Managing the huge volume of telemetry information required to support flight test at the Air Force Flight Test Center (AFFTC) has required new paradigms and system development strategies. These new ideas have resulted in the Aircraft Information Management System (AIMS), a system designed to meet the challenges of a new era in T&E. This paper discusses the AIMS design and function as background for the deeper issue of effective, efficient management of telemetry setup information. The information history model used in AIMS is presented and discussed. In the process of developing standards for the AIMS a methodology was discovered and successfully implemented for resolving information management issues in the framework of system development.
    • 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.
    • NAVSTAR Global Positioning System Applications for Worldwide Ionospheric Monitoring

      Moses, Jack; SPARTA, Inc. (International Foundation for Telemetering, 1992-10)
      The ionosphere is a critical link in the earth's environment for space-based navigation, communications and surveillance systems. Signals sent down by the GPS satellites can provide an excellent means of studying the complex physical and chemical processes that take place there. GPS uses two frequencies to ascertain signal delays passing through the ionosphere. These are measured as errors and used to correct position solutions. Since this process is a means of measuring columns of Total Electron Content (TEC), multiple top-soundings from the GPS constellation could provide significant detail of the ionospheric pattern and possibly lead to enhancement of predictions for selectable areas and sites. This paper addresses transforming the GPS propagation delays (errors) into TEC and providing TEC contours on a PC-style workstation in real and integrated time and discusses a worldwide ionospheric network monitoring system.

      Gelhaar, B.; Alvermann, K.; Dzaak, F.; Institute For Flight Mechanics (International Foundation for Telemetering, 1992-10)
      For research purposes on helicopter rotor acoustics a large data acquisition system called TEDAS (Transputer based Expandable Data Acquisition System) has been developed. The key features of this system are: unlimited expandability and sum data rate, local storage of data during operation, very simple analog anti aliasing filtering due to extensive digital filtering, and integrated computational power which scales with the number of channels. The sample rate is up to 50 kHz/channel, the resolution is 16 bit, 360 channels are realized now. TEDAS consists of blocks with 8 A/D converters which are controlled by one transputer T800. The size of the local memory is 4 Mbyte. Any number of blocks (IDAM = Intelligent Data Acquisition Module) can be combined to a complete system. Data preprocessing is done in parallel inside the IDAMs. As for 16 bit systems the analog antialiasing filtering becomes a dominant factor of the costs, delta sigma ADCs with oversampling and internal digital filtering are used. This produces an exact linear phase and a stop band rejection of -90 dB.
    • A Brief Look at Delta Modulation

      Ugarte, Alberto (International Foundation for Telemetering, 1992-10)
      The principle behind delta modulation systems is introduced. Having developed the principles of delta modulation systems, a system that performs delta modulation is developed and tested to see how well the system performs by using sinusoids and speech as the input to the system. This is then followed by a comparison of delta modulation and pulse code modulation to show that, overall, delta modulation is better than pulse code modulation.

      Mohd, Maqsood A.; McLaughlin, James J. Jr; Eglin Air Force Base (International Foundation for Telemetering, 1992-10)
      Telemetry operation is used extensively on a typical Department of Defense (DOD) test range to transfer data from an airborne transmitter to a ground receiver. The conventional telemetry systems employed are usually narrow-band systems. When a large number of airborne transmitters need to transfer data simultaneously to a ground station, a spread spectrum modulation scheme can be used. The drawback of such a scheme, however, is the large emission bandwidth required. The present frequency channeling plans in the telemetry band do not support frequency approval of large bandwidth data telemetry systems. However, a key requirement for obtaining the frequency approval can be satisfied if it can be shown that the spread spectrum modulated signal does not interfere with other systems in the same band. That is, the spread spectrum telemetry systems (SSTS’s) are feasible if these systems are electromagnetically compatible with the existing narrow-band telemetry receivers (NBTR’s) in their immediate environment. The electromagnetic compatibility (EMC between the SSTS transmitters and the conventional NBTR would promise the beginning of a new era for the telemetry operations on a DOD test range. This paper develops a methodology to establish the EMC between multiple airborne transmitters of an SSTS employing the code division multiple access (CDMA) technique and a ground-based conventional NBTR on a typical DOD test range operating simultaneously in the same band. The paper calculates the electromagnetic interference (EMI) levels between the SSTS and the NBTR to establish the EMC between the two systems.
    • Multichannel Digital Signal Processor Based Red/Black Keyset

      Smith, Quentin D.; Communications Systems Technology, Incorporated (CSTI) (International Foundation for Telemetering, 1992-10)
      This paper addresses a method to provide both secure and non-secure voice communications to a DS-1 network from a common keyset. In order to comply with both the electrical isolation requirements and the operational security issues regarding voice communications, an all-digital approach to the keyset was developed based upon the AD2101 DSP. Protocols that are handled by the keyset include: Multiple PTT modes, hot mike, telephone access, priority override, direct access, indirect access, paging, and monitor only. Special features that are addressed include: independent channel by channel assignment of access protocols, headset assignment, speaker assignment, and PTT assignment. Multiple microprocessors are used to implement the foregoing as well as down-loadable configurations, remote keyset control and monitoring, and composite audio outputs. Partitioning of the digital design provides RED to BLACK channel isolation and RED channel to AC power isolation of greater than 107 dB.

      Mayer, Robert; McDaniels, James; Kalil, Lou F.; Aydin Computer & Monitor Division; NASA (International Foundation for Telemetering, 1992-10)
      In the event of a NASA Space Shuttle mission landing at the While Sands Missile Range, White Sands, New Mexico, a data communications system for processing Shuttle’s telemetry data has been installed there in the Master Control Telemetry Station, JIG-56. This data system required a Viterbi decoder since the Shuttle’s data is convolutionally encoded. However, the Shuttle uses a nonstandard code, and the manufacturer which in the past has provided decoders for Shuttle support, no longer produces them. Since no other company produced a Viterbi decoder designed to decode the shuttle’s data, it was necessary to develop the required decoder. The purpose of this paper is to describe the functional performance requirements and design of this decoder.

      Salley, Thomas; Thorssell, Steven E.; Metraplex Corporation (International Foundation for Telemetering, 1992-10)
      IRIG 106-86 Chapter 8 describes the standard for acquisition of MIL-STD-1553 traffic flow. All incoming words (command, status, or data) are transmitted and fill words are used to maintain continuous data output. If all incoming words are not needed, or if other data such as sampled analog data from transducers are also to be transmitted, then a different approach is warranted. Selected data from the avionics bus can be placed into predefined PCM words, eliminating the transmission of useless data, and optimizing the bandwidth available to a Class I telemetry system. The engineering considerations and constraints for avionics bus data acquisition and analysis will be explored in this paper.
    • ESA Tracking Systems

      Girardey, Catherine C.; California Institute of Technology (International Foundation for Telemetering, 1992-10)
      This paper presents the tracking systems currently used at ESA. Two systems are described: Meteosat Ranging System (MRS), and Multi-Purpose Tracking System (MPTS). The MRS is presently in operational use on Meteosat. It has been designed to meet the need for a simultaneous multi-point ranging in a channel shared with other services. As a result, a new code ranging technique, based on split-phase-level data formats, has been designed and developed. The MPTS (previously Deep Space Tracking System - DSTS) was first developed and deployed for the Giotto mission. At a later stage, a near-earth capability has been added to the system, thereby creating a truly multi-purpose tracking system. The ranging signal employed in the MPTS makes use of the good properties of both the PN code type of ranging system and the tone ranging system. The concept, architectural design, capabilities and performance of these systems are presented in this paper. Finally, insight into the European Data Relay Satellite and Data Relay User Satellite ranging systems is given.

      Ricker, William; Kolb, John Jr; Aydin Vector Division (International Foundation for Telemetering, 1992-10)
      Due to the vast amount of data required to be collected for design/performance analysis of operational and development systems, there has evolved a real requirement for a high-speed, large capacity, data collection/record system in a small Flight/Ruggedized package. This need is realized by several user communities and factors which include the evolution of small operational vehicles (airborne, land and UAV’s), the desire of weapons manufacturers/integrators to be independent from the vehicle during vehicle integration, and a general need for a field/airborne, reliable portable data collection system for intelligence gathering, operational performance verification and on-board data processing. In the Air Defence community, the need for a ruggedized record system was highlighted after Desert Storm, in which the operational performance of the Patriot Missile was questioned and data collection was not performed to support the performance. The Aydin Vector Division in conjunction with the prime contractor, has come up with a solution to this problem which utilizes a commercially available helical scan 8mm data storage unit. This solution provides a highly reliable record system, ruggedized for airborne and field environments and a low price in comparison with the more traditional approaches currently offered. This paper will describe the design implementation of this small ruggedized, flight worthy Data collection system deemed the ATD-800. It will also discuss the performance and limitations of implementing such a system, as well as provide several applications and solutions to different operational environments to be encountered. Additionally, the paper will conclude with several product enhancements which may benefit the flight test, operational and intelligence communities in the future.
    • Synchronization of the Edwards Digital Switch

      Eslinger, Brian; Science Applications International Corporation (International Foundation for Telemetering, 1992-10)
      The Air Force Flight Test Center (AFFTC) at Edwards, California has installed the Edwards Digital Switch (EDS). The EDS is a DS-1 switch capable of switching voice, encrypted voice, and Time Space Position Information (TSPI) data. Communicating encrypted voice and TSPI data reliably from the EDS to any other communication system requires the two systems operate using the same frequency reference. The need to communicate with other test ranges and over commercially leased lines using the EDS requires synchronization to a standard frequency source. The current synchronization method used at the AFFTC is unacceptable for the EDS. A hierarchal system of synchronization networking will be implemented to provide a common reference to each of the systems interfacing the EDS. The Master Timing Station (MTS), which provides synchronization reference to most of the AFFTC resources, is aging and must be upgraded. The upgrade of the MTS and the restructuring of the synchronization signal distribution will be completed simultaneously. Traceability to the United States Naval Observatory (USNO) and the National Bureau of Standards (NBS) is required to provide the necessary synchronization to allow the EDS to interface reliably with other systems. The Global Positioning System (GPS) is being considered as the primary source for frequency calibration traceable to the USNO and NBS.
    • Uniform Access to Signal Data in a Distributed Heterogeneous Computing Environment

      Jeffreys, Steven; BBN Systems and Technologies (International Foundation for Telemetering, 1992-10)
      One of the problems in analyzing data is getting the data to the analysis system. The data can be stored in a variety of ways, from simple disk and tape files to a sophisticated relational database system. The variety of storage techniques requires the data analysis system to be aware of the details of how the data may be accessed (e.g., file formats, SQL statements, BBN/Probe commands, etc.). The problem is much worse in a network of heterogeneous machines; besides the details of each storage method, the analysis system must handle the details of network access, and may have to translate data from one vendor format to another as it moves from machine to machine. This paper describes a simple and powerful software interface to telemetry data in a distributed heterogeneous networking environment, and how that interface is being used in a diagnostic expert system. In this case, the interface connects the expert system, running on a Sun UNIX machine, with the data on a VAX/VMS machine. The interface exists as a small subroutine library that can be linked into a variety of data analysis systems. The interface insulates the expert system from all details of data access, providing transparent access to data across the network. A further benefit of this approach is that the data source itself can be a sophisticated data analysis system that may perform some processing of the data, again transparently to the user of the interface. The interface subroutine library can be readily applied to a wide variety of data analysis applications.

      Mason, Terry; Avalon Electronics Ltd (International Foundation for Telemetering, 1992-10)
      In recent years, many designers have turned to digital techniques as a means of improving the fidelity of instrumentation data recorders. However, single and multi-channel recorders based on professional VHS transports are now available which use innovative methods for achieving near-perfect timebase accuracy, inter-channel timing and group delay specifications for long-duration wideband analog recording applications. This paper discusses some of the interesting technical problems involved and demonstrates that VHS cassette recorders are now a convenient and low cost proposition for high precision multi-channel wideband data recording.
    • 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.
    • A Software Architecture for Realtime Data Acquisition, Instrument Control and Command Processing

      Tolat, Viral V.; Stanford University (International Foundation for Telemetering, 1992-10)
      In this paper we describe the flight software for the SETS (Shuttle Electrodynamic Tethered System) experiment. The SETS experiment will fly as part of the TSS-1 (Tethered Satellite System) experiment on STS-46 currently scheduled for July 1992. The software consists of two major components: the SETSOS (SETS Operating System) and the SETS Application. The SETSOS is a UNIX-like operating system developed especially for realtime data acquisition, instrument control and command processing. The SETSOS, like all operating systems, provides resource management for application programs. It is UNIX-like in that access to resources is provided through a standard set of UNIX system calls. The SETSOS also implements the standard UNIX I/O model and a hierarchical file system. In addition to providing access to physical devices, the SETSOS provides support for two virtual devices: a packet-based data device and a command device. The packet-based data device is used by applications to place data into the telemetry stream. The command device is used to manage commands from the command uplink as well as other sources including other applications and other processors. The SETS Application is the primary program which runs under the SETSOS to handle data acquisition, instrument control and command processing. It executes as 5 separate processes, each performing a special task. The tasks include housekeeping data acquisition, limit checking, timeline management, and command processing. The processes communicate via shared memory. Time critical processing is coordinated by using signals and interrupts. In addition to a description of the software, we will discuss the relative merits and tradeoffs of using such a system design for command processing and data acquisition.
    • An Integrated Approach to Real Time Flight Test as Seen from Down Under

      Slezak, Ken; Crouch, Viv; Loral Data Systems; Aircraft Research and Development Unit (International Foundation for Telemetering, 1992-10)
      The Aircraft Research and Development Unit (ARDU) is the flight test authority for the Royal Australian Air Force (RAAF). ARDU was born out of a requirement to handle the testing of developmental aircraft and weapons during Word War II. Its nucleus was established in 1941 and one of its first tasks was to evaluate the flying qualities and performance of captured Japanese aircraft. Today, ARDU provides "one-stop shopping" for flight testing all aircraft, weapons and systems in the RAAF and Australian Army Inventory. As directed by the RAAF, ARDU also performed flight testing on Royal Australian Navy aircraft, as well as novel and unique aircraft such as lighter-than-air and museum restored aircraft that are of historical importance.

      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.

      Johnson, Carl E.; NASA (International Foundation for Telemetering, 1992-10)
      The ethernet technology has vastly improved the capability to make real-time decisions during the flight of a vehicle. This asset combined with a PC telemetry data processor and the power of a high resolution graphics workstation, allows the decision makers to have a highly reliable graphical display of information on which to make vehicle related safety decisions in real-time.