• COMPUTER-FRIENDLY HIGH RATE DIGITAL CASSETTE RECORDERS

      Kayes, Edwin A.; Penny & Giles Data Systems Ltd (International Foundation for Telemetering, 1992-10)
      The world of instrumentation data recording has traditionally been concerned with recorder performance in terms of bandwidth, data rate, tape speed and recording time, with the apparently unceasing trend to record more and more data. However, while this may remain a valid perspective for data acquisition, the increasing requirement to integrate equipment into computer based environments has resulted in the need for greater emphasis to be applied to such parameters as data control and interfacing when specifying digital data recording systems. This paper addresses these operational issues and describes the practical implementation of a computer friendly digital cassette recorder which provides a common platform for both high rate data acquisition and computer based data analysis.
    • Neural Network Application to Telemetry Frame Synchronization

      Massey, David E.; Goddard Space Flight Center (International Foundation for Telemetering, 1992-10)
      This paper looks into the use of neural network software as applied to the classical signal to noise concern when dealing with space to ground data communications. Use of a digital neural network to extend the correlation range of Pulse Code Modulation (PCM) down into noise is investigated. Conventional synchronization pattern correlation is done with digital logic comparisons on a sliding window with a set number of bit mismatch errors allowed. Correlation with a neural network does pattern recognition with a weighted network of artificial neurons that have been trained to recognize the sync pattern within noise. The output of such a neural network will produce a best guess of the correct pattern.
    • Software Considerations in the Control of Digital Communications Switching Systems

      Ward, Ronald P.; Communications Systems Technology, Incorporated (CSTI) (International Foundation for Telemetering, 1992-10)
      Today's complex implementations of integrated packet and circuit switched digital communications networks demand that the software used for controlling these systems be robust, fault tolerant, and capable of runtime recovery from all but the most severe of operational errors. The typical modern switched communications system includes the use of multiple circuit switches, each with potentially thousands of end-user interfaces. Further, these switches are often inter-connected to each other via high-capacity trunks. A single connection between two end-user interfaces often traverses a number of intermediate circuit switches in order to effect the end-to-end communications desired. In this complex, distributed environment, the establishment and dissolution of end-to-end user connections involve far more than simple binary connection states indicating the existence, or non-existence, of a link. More commonly, a single end-to-end connection requires multiple node links across multiple, heterogeneous interfaces. The command and control software used to establish, monitor, and dissolve these connections must be capable of dealing with errors which arise at any node along the way in a consistent and reliable manner. Most critically, the system software must be capable of maintaining an accurate, multi-level mapping of distributed resources' availability, allocation, and status. Further, the software must have the capability of "healing itself" during operational run-time when it can, and of accurately reporting the nature of inconsistencies caused by anomalous events that cannot be fixed on the fly. The Edwards Digital Switch (EDS), developed by CSTI, provides a case study of possible solutions, and potential pitfalls, that can arise in the design, development, and implementation of the controlling software in today's dynamic, distributed communications' system architectures.
    • TELEMETRY TRANSMITTER ACCEPTANCE TESTING AT WHITE SANDS MISSILE RANGE

      Wyman, Richard J.; White Sands Missile Range (International Foundation for Telemetering, 1992-10)
      White Sands Missile Range (WSMR) is the largest overland test range, operated by the Department of Defense, in the United States. It encompasses approximately 4000 square miles of south-central New Mexico. WSMR supports various missile, weapons system, and instrumentation development tests of the Army, Navy, Air Force, NASA, and other agencies, and controls the airspace and electromagnetic (EM) radiation on and around WSMR. Due to the large number of users at WSMR, the EM spectrum has become increasingly crowded and EM radiation control has become extremely important. For this reason, WSMR Regulation 105-10 (Telemetry Radio Frequency (RF) Spectrum Utilization) was adopted and states that all TM transmitters proposed for use at WSMR must be approved. These transmitters are approved upon determination that they meet the requirements set forth in the current Range Commander’s Council (RCC) Inter-Range Instrumentation Group (IRIG) Document titled “Telemetry Standards”. (NOTE: This document will hereafter be referred to as RCC Document 106). This determination is performed by the White Sands Missile Range Director of Information Management (WSMR-IM) in the form of acceptance testing and analysis. This acceptance testing consists of the verification and analysis of the transmitter’s frequency stability, output power, and spurious and harmonic emission levels, in order to prevent EM interference between the many range users. The current test methodology will be explored in sufficient detail so that potential range users will know the procedures used to qualify TM transmitters for use at WSMR. Past methods and future testing considerations will also be briefly examined.
    • SGLS COMMAND DATA ENCODING USING DIRECT DIGITAL SYNTHESIS

      Gordon, Michael; Cincinnati Electronics Corporation (International Foundation for Telemetering, 1992-10)
      The Space Ground Link Subsystem (SGLS) provides full duplex communications for commanding, tracking, telemetry and ranging between spacecraft and ground stations. The up-link command signal is an S-Band carrier phase modulated with the frequency shift keyed (FSK) command data. The command data format is a ternary (S, 1, 0) signal. Command data rates of 1, 2, and 10 Kbps are used. The method presented uses direct digital synthesis (DDS) to generate the SGLS command data and clock signals. The ternary command data and clock signals are input to the encoder, and an FSK subcarrier with an amplitude modulated clock is digitally generated. The command data rate determines the frequencies of the S, 1, 0 tones. DDS ensures that phase continuity will be maintained, and frequency stability will be determined by the microprocessor crystal accuracy. Frequency resolution can be maintained to within a few Hz from DC to over 2 MHZ. This allows for the generation of the 1 and 2 Kbps command data formats as well as the newer 10 Kbps format. Additional formats could be accommodated through software modifications. The use of digital technology provides for encoder self-testing and more comprehensive error reporting.
    • 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.
    • A Fast Realtime Simulation of a Complex Mechanical System on a Parallel Hardware Architecture

      Oertel, C.-H.; Gelhaar, B.; Institute for Flight Research (International Foundation for Telemetering, 1992-10)
      Real-time computation speed is an additional requirement for simulations. It is necessary for 'man-in-the-loop' systems like flight simulators and for 'hardware-in-the-loop' systems where real components like new closed loop controllers are tested under realistic conditions. In the past a lot of companies have designed and built special purpose simulation computers which are very powerful but expensive and not handy enough for 'in-the-field-tests'. The progress in computer science shows a trend to distributed systems where multiple processors are running in parallel to improve the performance dramatically. At the DLR Institute for Flight Mechanics a computer system, based on the transputer, was designed to achieve the real-time simulation capabilities for the ROTEST model rotor. This four-bladed rotor is a 2.5 scale of the BO105 main rotor, equipped with elastic blades, operating at 1050 rpm. After an introduction to the ROTEST rotor, including the demands upon the simulation, a short introduction to transputers and the associated philosophy is given. The next part of the paper presents the characteristics of the simulation model, its mathematical description and the transputer architecture on which it is running. In the last part of the paper the input and output processes to the simulation are described. This includes a real-time representation of the rotor and an oscilloscope like output device, as well as analogue input and output devices to a controller.
    • A Transputer Based 3D-Graphics System

      Alvermann, Klaus; Institute for Flight Research (International Foundation for Telemetering, 1992-10)
      The Institute for Flight Mechanics operates the flying simulators ATTAS (a wing aircraft) and ATTHeS (a helicopter), their respective ground based simulators and uses realtime and offline simulations for system identification and other purposes. Based on a parallel transputer architecture, a 3D-graphics tool for visualization and view simulation to be used with the simulations has been developed. The tool uses data received by telemetry, realtime data from a simulation, or recorded data to show the movement and orientation of an aircraft in realtime 3D-graphics. The aircraft or scene may be observed from any point of view. Placing the camera in the cockpit of the aircraft and showing the environment results in a view simulation. The use of a parallel transputer architecture allows a modular and scalable structure, i.e. the system may be adapted to the needs of the application. By adding software modules and transputers we may include 24 bit colour, shadowing, a higher resolution, a better shading algorithm or other things which are required by an application. On the other hand we may remove transputers to get a small and cheap system if the requirements are low. A small system may consist of only 8 transputers, whereas a big system may include 50 or 60 transputers.
    • Conserving Telemetry Bandwidth in Flight Test Instrumentation

      Hoefner, Carl E.; Interstate Electronics Corporation (International Foundation for Telemetering, 1992-10)
      The more sophisticated weapons systems become, the more information is required for thorough system test and evaluation. With the increasing capability in instrumentation technology, more data is being generated, and this in turn is stressing the amount of telemetry bandwidth available. In the training community this is even more serious because of the extremely large training areas and number of players involved. Total data bandwidth required becomes an insurmountable problem. When examining the telemetry data requirements for each application, we must constantly remember that information transfer is the key, not necessarily the transfer of large amounts of data. This problem can be solved by applying instrumentation techniques that enable significant information transfer without requiring excessive data bandwidth of the telemetry system. The general approach to the solution of this problem has been applied to the U.S. Government's SDI Program. Here the total system is modeled in a computer, and a complete test exercise can be simulated. Only significant information from the vehicle under test is telemetered periodically to verify the simulation. Another approach has been postulated by the U.S. Defense Advanced Research Projects Agency (DARPA) in their SIMNET studies. Here an exercise is simulated both on the ground and in the test vehicle, and information is transmitted from the test vehicle only when the actual vehicle performance differs from the simulation. By using techniques of this type, savings of a factor of 10 or more can be experienced in the required telemetry bandwidth. This paper examines various techniques that can be used to minimize required telemetry bandwidth.
    • 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.
    • TECHNIQUES FOR SYNCHRONIZING THERMAL ARRAY CHART RECORDERS TO VIDEO

      Gaskill, David M.; Astro-Med, Inc. (International Foundation for Telemetering, 1992-10)
      Video tape is becoming more and more popular for storing and analyzing missions. Video tape is inexpensive, it can hold a two hour test, and it can be edited and manipulated by easily available consumer electronics equipment. Standard technology allows each frame to be time stamped with SMPTE code, so that any point in the mission can be displayed on a CRT. To further correlate data from multiple acquisition systems, the SMPTE code can be derived from IRIG using commercially available code converters. Unfortunately, acquiring and storing analog data has not been so easy. Typically, analog signals from various sensors are coded, transmitted, decoded and sent to a chart recorder. Since chart recorders cannot normally store an entire mission internally, or time stamp each data value, it is very difficult for an analyst to accurately correlate analog data to an individual video frame. Normally the only method is to note the time stamp on the video frame and unroll the chart to the appropriate second or minute, depending on the code used, noted in the margin, and estimate the frame location as a percentage of the time code period. This is very inconvenient if the telemetrist is trying to establish an on-line data retreival system. To make matters worse, the methods of presentation are very different, chart paper as opposed to a CRT, and require the analyst to shift focus constantly. For these reasons, many telemetry stations do not currently have a workable plan to integrate analog and video subsystems even though it is now generally agreed that such integration is ultimately desirable.
    • GPS-Trak Low Cost Alternative to Auto-Tracking Using GPS and Multimode Single Axis Antenna Techniques

      Sullivan, Arthur; Arthur Sullivan & Associates (International Foundation for Telemetering, 1992-10)
      The GPS Satellite System provides precise determination of time, space, and position of aerospace (airborne) vehicles during flight and flight test situations. The cost of "GPS" equipment has been decreasing dramatically -- a phenomenon similar to that which was experienced with "hand held" calculators 20 years or so ago. By the use of a multigain (and beam) antenna and GPS, a very low cost single axis system can be utilized for reception of telemetry and at the same time to provide accurate position, velocity, and acceleration information concerning the airborne vehicle.
    • 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.
    • DIGITAL TAPE RECORDING IN AN AIRBORNE DATA ACQUISITION SYSTEM

      Coonce, Kenneth G.; Strahmann, Jens; Loral Data Systems; Deutsche Airbus (International Foundation for Telemetering, 1992-10)
      This paper describes the functionality of an airborne telemetry system which collects data from standard PCM, MIL 1553 and ARINC data sources and records this data to an AMPEX DRCSi Digital Tape Recorder while supporting concurrent realtime data processing and display functions. The system includes data acquisition equipment, digital to analog capability, data simulation and a wide range of data preprocessing capability. Emphasis is given to the implementation of the AMPEX recorder interface. The entire system is composed of data acquisition equipment to directly input measurements, a telemetry front end to collect PCM, MIL 1553 and ARINC 429 & 561 data, a host computer to control and monitor the setup, recording and distribution of data and a pair of high resolution color workstations for operator control and data display. This equipment is housed within a single, military-type electronic enclosure which is loaded into the cargo bay of the aircraft as a single unit and manned by two people during flight. The Digital Tape Recorder provides for a large data capacity and very high data rates. Special I/O requirements, data rates and data selection options are discussed. Consideration is given for the best test flight utilization of the AMPEX recorder in both acquisition and playback modes.
    • AN EVENT TIMING SYSTEM USING FIBER OPTIC SENSORS

      Otis, Craig H.; Lewis, Steve M.; Far West Sensor Corp. (International Foundation for Telemetering, 1992-10)
      A fiber optic event timing system was developed for the High Speed Test Track at Holloman Air Force Base, Alamogordo, NM. The system uses fiber optic sensors to detect the passage of rocket sleds by different stations along the track. The sensors are connected by fiber optic cables to an electronics package that records the event time to a resolution of 100 nanoseconds. By use of a GPS receiver as the timebase, the event time is stored to an absolute accuracy of 300 nanoseconds. Custom VMEbus boards were developed for the event timing function, and these boards are controlled by a programmable high speed sequencer, which allows for complicated control functions. Each board has 4 electro-optic channels, and multiple boards can be used in a VMEbus card cage controlled by a single board computer. The system has been tested in a series of missions at the Test Track.
    • CAIS AIRBORNE HARDWARE

      Lamy, M. F.; Ellis, D. H.; SCI Systems (International Foundation for Telemetering, 1992-10)
      The Common Airborne Instrumentation System (CAIS) is designed as a general purpose system for flight test applications into the next century. The system has an open architecture which readily permits the addition of new equipment as the need arises. This paper describes the current complement of airborne hardware as well as the approach to the design of the open architecture. This paper is presented as a companion to the CAIS overview prepared for this conference.
    • Real Time Telemetry Data Synthesis with the TMS320C25

      Jun, Yao; Shi-yan, Liu; Xinan Electronic Engineering Institute (International Foundation for Telemetering, 1992-10)
      This paper presents the method of real time telemetry data synthesis for multi-beams and multi-receivers system in theory. For the practical implementation, we introduce a TMS320C25-based data synthesis board. Through a large number of simulating experiments, the satisfactory results are obtained, which obviously improve the performance of telemetry system. Therefore, all those technigues and results have the value of practical applications.
    • ELECTROMAGNETIC COMPATIBILITY BETWEEN SPREAD SPECTRUM AND CONVENTIONAL TELEMETRY SYSTEMS: THE KEY TO A NEW ERA FOR DOD TEST RANGES

      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.
    • High-Speed Distributed Digital Instrumentation System

      Donlan, Brian; Baumgartner, Michael; Science Applications International Corporation (International Foundation for Telemetering, 1992-10)
      An distributed architecture for high-speed digital and analog instrumentation is discussed. This architecture supports the collection, formatting, recording of both conventional telemetry (analog & PCM) and high-speed digital data. Remotely located instrumentation data interface units provide data acquision close to the data sources. The remotely located units are connected via high-bandwidth fiber optic links to a central formatting and recording unit. Data is recorded on digital rotary head recorders. Graphic workstations provide visual data displays for test control and monitoring. This system was developed to handle the high-speed data acquision requirements of advanced avionics sensor and seeker systems, however, it provides the basis for many other applications.
    • A Data to Video Encoding and Decoding System

      Jensen, Peter; Merlin Engineering Works (International Foundation for Telemetering, 1992-10)