• Hypermedia and Expert Systems Applied to Space Vehicle Monitoring & Control

      Bost, J. D.; Le, T. C.; Mangan, P. K.; Meloan, M. D.; Sutton, S. A.; Turner, S. R. (International Foundation for Telemetering, 1989-11)
      The Defense Meteorological Satellite Program (DMSP) weather satellite supports worldwide defense operations by the acquisition of global visual and infrared cloud data and other specialized meteorological, oceanographic, and solar data. In support of DMSP, prototypes are currently under development that will demonstrate the viability of expert systems, real-time graphics, and hypermedia-based information navigation for space vehicle monitoring & control.
    • International Participation in AOS Standards Development

      Lenhard, Klaus G.; European Space Agency (International Foundation for Telemetering, 1989-11)
      During the current decade, international cooperation in space projects has become more and more popular and this trend is increasing. Initially, this involved only single missions with agencies flying payloads on other agencies' spacecraft. Later, this trend continued with international ventures, involving different agencies. In the immediate future, even more challenging scenarios are foreseen. The best known example and prime driver for such sophisticated missions will be the Space Station Freedom and its participating partners' spacecraft. Some of the international missions (ESA missions) are described briefly in this paper, in order to set the scene for a better understanding of the complex needs for standards within advanced orbiting systems. These ventures call for efficient means for cooperation and interoperability. Part of these requirements can be met by following international standards for space communications and space data systems. The Consultative Committee for Space Data Systems (CCSDS) undertook the task of integrating the space data systems requirements and developing appropriate recommendations for data systems standards for these Advanced Orbiting Systems (AOS). All international partners in the Space Station Freedom Program participated in the definition, development, and review of the AOS recommendations. The need for better cooperation in space communications via data relay satellite prompted the formation of a three party international panel called the Space Network Interoperability Panel (SNIP). An important aspect is the need for verification and validation of the concept and of the detailed technical recommendations. For the immediate future, special compatibility campaigns, involving the international agencies are planned in order to ensure the smooth application and functioning of the AOS recommendations.
    • Data Rate Reduction Using a Digital Anti-Aliasing Filter

      Lee, Kyong H.; Maschhoff, Robert H.; Gulton Data Systems (International Foundation for Telemetering, 1989-11)
      In this paper we explore the limits of data rate or sample rate reduction that can be accomplished by sharp cutoff band limiting filters in a PCM data acquisition system. The results with practical analog filtering techniques are compared with those possible with digital filtering techniques. A typical 2:1 reduction in telemetry bit rate is shown to be practical using digital vs analog techniques. The resultant sample rates as low as 2.5 times the filter cutoff frequency has implications in the reconstruction algorithms which are also discussed. It is shown that by using practical and appropriate interpolation techniques or sample rate multiplication processes the data fidelity can be preserved. Thus the data user is assured that no information is being lost.

      NAGARAJ, S.R.; RAJANGAM, R.K.; ISRO SATELLITE CENTRE (International Foundation for Telemetering, 1989-11)
      The Vector cardiography is the 3 dimensional study of Electrocardiographic responses of the human heart. A Vector cardiograph (VCG) instrument was designed and developed to monitor the Cardiographic responses of the Indian payload specialist under zero G conditions in the US Space Shuttle during the scheduled INSAT-lC launch. Accordingly the proposal made by Department of Space for using the vector cardiograph measurement in the Space Shuttle was accepted. A VCG unit was developed under the joint collaboration of HAL, Hyderabad and ISAC-ISRO. This paper brifly describes the design aspects of the VCG instrument, the qulification tests conducted on the same for space application and the final test results obtained during the process. Basically the instrument was built around a Hybrid Instrumentation amplifier and other interfaces for recording the signal into an audio taperecorder.

      VERHAEGHE, Jacques; Project Engineer, Techniphone, France (International Foundation for Telemetering, 1989-11)
      Verifying the quality of a PCM (or PAM) telemetry system is an important concern before any launch. A frame simulator generated test is definitely inchoate to exercise the link’s real world disturbances response behavior. It should be completed with tests involving some disturbances measurements.
    • A GPS Disciplined Rubidium Clock

      Dewey, Wayne; Kinemetrics/TrueTime (International Foundation for Telemetering, 1989-11)
      Sub-Microsecond timing accuracy for event tagging and multisite synchronization is possible using the Global Positioning System. In order to maintain a high degree of accuracy during periods when no satellites are visible, a highly stable local time base is required. For those cases which require Cesium Oscillator stability, initial cost and continuing maintenance of the Cesium Oscillator must be considered. A viable alternative is attained by using the Global Positioning System and an oscillator disciplining process. With this system, near Cesium performance can be achieved using a more rugged lower cost Rubidium oscillator. Additionally, when 24 hour satellite coverage becomes available, system performance may surpass that of a Cesium in long term stability as well as long term drift. This presentation describes the system components, including Global Positioning System receiver, Miniaturized Controllable Rubidium Oscillator and Global Positioning System Clock. Clock timing accuracy and short and long term frequency stability results are discussed along with the control algorithms used in the disciplining process. A brief discussion of the computer modeling tools used is also presented.

      Daniels, R. Michael; Sandia National Laboratories (International Foundation for Telemetering, 1989-11)
      As a national laboratory, one of Sandia’s missions requires the development of airborne telemetry systems for acquisition and transmission of in-flight data and for control of flight vehicle functions. These telemetry systems are usually produced in small numbers and have very limited application. Before the flight test, systems undergo extensive functional and environmental testing. During the flight test, a method of sequencing through a predetermined flight program is required. To aid in the development of these telemetry systems, Controllers and Programmers have been developed. The telemeter uses an external Controller during functional and environmental testing to allow access to various internal telemeter functions. An on-board Programmer is used to manage the predetermined sequence of events throughout the flight test. Previously, such ControllerProgrammer systems have consisted of a single-purpose apparatus with limited scope. These systems would be re-designed with each telemetry system -- necessitating additional expenditures in manpower and hardware. This paper discusses an advanced Controller - Programmer system for telemetry applications. It is adaptable to a variety of telemeters and offers a number of benefits. The Controller has the ability to download flight sequence information to the Programmer via a serial communication link, even when the telemeter is assembled in the test vehicle. It also has the capability to log environmental test data and charge telemetry system batteries. Additionally, the Controller provides a user-friendly, reconfigurable method of command entry and a graphic display of telemetry parameters. The Programmer, in addition to communicating with the Controller, has the capability of flight sequence resumption after complete power failure via non-volatile storage of operating parameters. The programmer can control a virtually unlimited number of flight test functions yielding a high degree of design flexibility, and, being microcontroller based, is also power and space efficient.
    • 1553 Data BUS/PCM Multiplexer System

      Breedlove, Phil; Malone, Earl; Loral/Conic; Boeing Aerospace (International Foundation for Telemetering, 1989-11)
      A Telemetry system which integrates 1553 Bus data, DualSimplex bus data, vehicle performance data, and environmental sensor data multiplexing encompasses many interfacing constraints. The Engineering design considerations and hardware constraints required to implement this system are presented in this paper.

      CHAKRABORTY, S.K.; RAJANGAM, R.K.; ISRO SATELLITE CENTRE (International Foundation for Telemetering, 1989-11)
      The first Indian Remote Sensing Satellite was launched on 17th March 1988 from a Soviet Cosmodrome into a 904 Km Polar Sunsynchronous orbit. The data transmission from the satellite is at 5.2 Mega Bits/sec in S-Band and 10.4 Mega Bits/sec in X-Band. The payload data is formatted into custom made 8328 words format. A programmable unique versatile frame sync and Decommutation unit has been developed to test the data from the data handling system during its various phases of development. The system works upto 50 Mega Bits/sec and can handle frame sync code length upto 128 bits and a frame length of 2 Exp 20 bits. Provision has been made for programming the allowable bit errors as well as bit slippages, using a front panel setting. This paper describes the design and implementation of such a high bit rate frame synchroniser developed specially for IRS Spacecraft application. It will also highlight the performance of the system.
    • MIL-STD-1553 Data Acquisition System

      Landry, Michael; Loral Conic (International Foundation for Telemetering, 1989-11)
      The Range Commanders Council recently added a chapter to IRIG 106-86 which describes a standard for acquisition of MIL-STD-1553 traffic flow. A system has been developed which monitors bus traffic using the format described in the standard for encoding. In addition to bus data, PCM analog channels can be inserted into the telemetry steam. Due to the high bandwidth of the telemetry stream, real-time ground processing of the 1553 data is difficult. Therefore, a limited number of selective measurements taken from the bus traffic are available at fixed positions in the telemetry format for real-time monitoring of critical parameters. A discussion of hardware, software, encoding, and testing will be presented.

      Havey, Gary; Tanji, Todd; Olson, Richard; Wald, Jerry; Honeywell Systems and Research Center (International Foundation for Telemetering, 1989-11)
      Honeywell, under contract from NASA Johnson Space Center and Lockheed Engineering and Sciences Company, has developed a new tool for instrumentation data collection. The Stand-Alone Pressure Measurement Device (SAPMD) is part of a family of microminiature data recorders combined with sensors that can be be used as flight development instrumentation on aerospace vehicles and structures. NASA came to Honeywell with a need to collect absolute pressure data during ascent of the Shuttle on various points over the orbiter’s surface. Instrumentation for this data does not exist on current orbiters, and NASA must use computer modeling to determine structural loading calculations. The conventional approach of placing sensors and cabling inside the Shuttle’s frame combined with drilling holes for the pressure sensors was considered too costly and could weaken the orbiter’s structure. The SAPMD measures pressure at various locations on the space shuttle orbiter skin during ascent. In order to avoid the extensive impacts associated with wiring new measurements into the orbiter data system, the device is self contained, incorporating its own sensor, power supply, self-starting sensor, nonvolatile memory for sensor data, and a real-time clock for time reference. The device is small enough (6.28 in x 1.5 in. x 0.5 in.) to be mounted under the thermal protection system tiles and rugged enough to withstand the environments encountered at the interface between tiles throughout an orbiter mission. Data recorded during ascent is recovered after the mission without removing the device. Other sensors such as strain gauges for structural monitoring, vibration gauges for wing flutter, or differential pressure gauges can be used with this hardware.
    • Amarrm Warhead Compatible Telemetry

      Powell, David G.; Pacific Missile Test Center (International Foundation for Telemetering, 1989-11)
      During the final stages of the AMRAAM Full Scale Development effort a requirement for a miniature warhead compatible instrumentation system was established. Internal missile volume was not available to house the system but volume was identified within the external wiring harness cover. The system was required to have significant data handling capability and encryption, and had to withstand a severe environment on a small power budget. Several technologies were developed at the Pacific Missile Test Center to meet this challenge including Application-Specific Integrated Circuits (ASIC), surface mount technology, and thick and thin film hybrid microcircuits. In addition the state-of-the art in transmitters and power converters was stretched. The result was an encrypted PCM telemeter with 2 watt transmitter and antenna all in the missile wiring harness cover (along with the wires!)

      Meyer, Steven; Naval Weapons Center, China Lake, CA (International Foundation for Telemetering, 1989-11)
      During high-power microwave (HPM) testing, where the item under test is subjected to power levels up to several thousand W/cm , the RF energy present will make typical 2 telemetry RF links useless. Therefore, other means must be used to retrieve the data during the tests. One method to accomplish data retrieval is to replace the RF data link with a fiber-optic link. This is done by replacing the transmitter with a fiber-optic transmitter on the sending end and the RF receiver with a fiber-optic receiver on the receiving end. Although this sounds simple, it is not always so. Solutions for PCM and FM-FM systems are relatively straightforward, whereas PAM systems present a unique set of problems. This paper addresses possible solutions for PCM and FM-FM and three possible solutions for PAM, one being by using a PAM-to-PCM converter.

      Svensson, Ake; Maoz, Michael; Saab Missiles AB; RAFAEL; Aydin Vector Division (International Foundation for Telemetering, 1989-11)
      Aydin Vector Division has developed and manufactured an airborne, high shock, wideband FM/FM telemetry system for Saab Missiles AB in Sweden. This system was presented in the ITC Proceedings of 1988, Volume XXIV, pp 71-84 (Ref [1]). Three such systems were supplied. Saab Missiles AB also awarded Aydin Vector Division with an additional order for a larger number of high shock, computer based, specially designed, miniature PCM/FM airborne telemetry systems. These systems were developed, manufactured and supplied to Saab Missiles AB, and have been extensively and successfully used in the Swedish program. The PCM/FM telemetry package described in this paper was used for the system testing and the firing trials program of a mortar projectile, where the measurement requirements included micro processor interfaces, as well as a high amount of analog and bi-level data channels. The paper covers the specifications of the PCM/FM system mentioned above, the concept that was used to meet these specifications, the system’s mechanical and electrical design, the packaging technique and some of the test results.

      Qiu-Cheng, Xie; Zhong-Kui, Lei; Nanjing Aeronautical Institute (International Foundation for Telemetering, 1989-11)
      In this paper, twelve optimum group synchronization codes (n=31 to 42) for PCM telemetry systems are presented. They are the newest achievements up to now.

      Hammond, Victor W.; Stegall, Ralph L.; Gumb, Dana F.; Wilson, William H.; General Electric Company; Compudyne Corporation (International Foundation for Telemetering, 1989-11)
      Modern aircraft testing and training increasingly demand the use of multiple targets. A novel method to meet this requirement is to use the new AN/MPS-39 Multiple Object Tracking Radar (MOTR) with Vega Target Control System equipment. The AN/MPS-39 can be loosely described as the equivalent of ten AN/FPS-16 radars. This equivalency, due largely to the AN/MPS-39’s phased array antenna, immediately suggests the controlling of multiple target drones as an added capability to the radar’s basic and demonstrated function as a precision metric instrument. This paper demonstrates the adaptability of the AN/MPS-39 MOTR to the use of VTCS, thus exploiting the AN/MPS-39’s inherent capability to control multiple target drones simultaneously.

      Copeland, David J.; Aleman, Roberto M.; EVI, Inc.; Goddard Space Flight Center (International Foundation for Telemetering, 1989-11)
      The user G/T and EIRP requirements were determined for a data relay satellite link consisting of a forward link to 360 Mbps at 23 GHz and a return link to 2 Gbps at 26.5 GHz. Hardware for this data link would be a modular expansion to the NASA Data Link Module. Calculations were based on a data relay satellite model of predetermined characteristics patterned after the NASA Tracking and Data Relay Satellite (TDRS). The desired data rates could be achieved with a G/T of 21.7 dB/deg K (forward link) and an EIRP of 68.2 dBW (return link) for the user satellite. Hardware configurations meeting these requirements are discussed in terms of RF performance, efficiency, reliability, and modular flexibility. A planar array configuration emerges as the logical candidate for most NASA missions. Pertinent Ka-band technology and certain ongoing research efforts are reviewed. Areas of particular interest include new power device families, 0.25 um lownoise HEMT technology, and fiber optic distribution and control of RF arrays.
    • A Fully Digital Antenna Control System

      El Busch, Charles; Scientific-Atlanta, Inc. (International Foundation for Telemetering, 1989-11)
      Antenna control systems are typically a combination of digital time domain algorithms for relatively simple mathematical operations followed by analog frequency domain filtering for mechanical resonance compensation. This paper presents an innovative, fully digital control system that utilizes the advantages of both modern sampled time domain control methods and classical frequency domain conceptualization. The unit is designed to perform all functions of the antenna control problem in the digital domain including generation of command coordiantes, position, rate, torque loop closure, servo compensation, and torque bias processing. Problems related to analog processing such as offsets, drift, and dynamic range are completely avoided in the digital domain. Non-linear and adaptive filtering is used to correct system non-linearities due to saturation, backlash, friction, and dead band. Rate and acceleration limiting is provided in the digital processing along with an optimal state estimator that is used to dramatically decrease system servo errors for dynamic targets. Digital filtering is accomplished by utilizing an internal bi-linear transform between the frequency domain input parameters familiar to most control engineers and the cascaded z-transform filter coefficients used by the control algorithms. All control and servo control parameters are programmed into the units’ nonvolatile memory by the control engineer using an interactive terminal attached to a service port. Changes to the servo compensation that often required hours of analysis and electronic component changes can now be effected and evaluated in seconds. Final outputs from the unit are motor drive commands that are converted to analog form for power amplifier use. All control and status communication between the unit and a host computer or operator console is via a high speed, fiber optic, serial data link.
    • Advanced Concepts for Telemetry Data Systems

      Pritchard, James A.; National Aeronautics and Space Administration (International Foundation for Telemetering, 1989-11)
      Current telemetry data processing systems capabilities will have to be improved by as much as three orders of magnitude in order to handle the expected data rates of the Space Station era. National Aeronautics and Space Administration (NASA) processing systems can currently process telemetry data at an average input rate of about 100K bits per second while Space Station era data rates will average about 100M bits per second and could have peak rates of up to 1200 M bits per second. In order to meet the challenge of developing telemetry systems for processing high rate data at a reasonable cost, data processing and distribution systems must be data driven as opposed to being resource scheduled. If a system is to be data driven, data structures must contain a mechanism for routing of the data to its intended destination. Packet telemetry systems have been developed for the purpose of processing and routing telemetry data at higher rates than conventional time division multiplexed systems. Packet telemetry data standards are being developed by the international Consultative Committee for Space Data Standards (CCSDS) in order to facilitate development of packet telemetry systems both within NASA and international space agencies as well as for inter-agency cross support situations. These CCSDS Advanced Orbiting Systems (AOS) standards specify the overall architectural framework of future packet telemetry systems. The CCSDS AOS standard defines a CCSDS Principal Network (CPN) which covers the on-board, space link and ground systems and provides for asynchronous (e.g., Telemetry and Internetworking) and isochronous (e.g., Audio and Video) data transport services utilizing CCSDS Packets and Virtual Channels. In order to achieve efficient use of the limited resources of the space link, CCSDS Packets are multiplexed on to CCSDS Virtual Channels for transmission through the space link. This paper will mainly discuss changes to ground telemetry processing systems currently in use (such as the Packet Processor (PACOR) System), future systems under development (such as the Space Station Information System(SSIS) and the Customer Data Operations System (CDOS)), and how the CCSDS standards relate to these systems.
    • Versatile 1553 Muxbus Interface

      Dahan, MIchael; Instrumentation and Telemetry Systems (International Foundation for Telemetering, 1989-11)
      This paper presents a 1553 Muxbus Interface which can acquire data, selectively, from up to 3 redundant busses and process it for different airborne or ground test applications. The Interface is built using up to date electronic technology in order to overcome the problems encountered in 1553 protocol decoding and to insure proper data integrity