• Document Retrieval Triggered by Spacecraft Anomaly: Using the Kolodner Case-Based Reasoning (CBR) Paradigm to Design a Fault-Induced Response System

      Kronberg, F.; Weiner, A.; Morgan, T.; Stroozas, B.; Girouard, E.; Hopkins, A.; Wong, L.; James, M.; Kneubuhl, J.; Malina, R. F.; University of California, Berkeley; Omitron; NASA/Cal Tech Jet Propulsion Lab; Laboratoire d’Astronomie Spatiale (International Foundation for Telemetering, 1996-10)
      We report on the initial design and development of a prototype computer-mediated response system, the Fault Induced Document Officer (FIDO), at the UC Berkeley Center for EUV Astrophysics (CEA) Extreme Ultraviolet Explorer project (EUVE). Typical 24x7 staffed spacecraft operations use highly skilled expert teams to monitor current ground systems and spacecraft state for responding to anomalous ground system and spacecraft conditions. Response to ground system error messages and spacecraft anomalies is based on knowledge of nominal component behavior and the evaluation of relevant telemetry by the team. This type of human-mediated operation is being replaced by an intelligent software system to reduce costs and to increase performance and reliability. FIDO is a prototype software application that will provide automated retrieval and display of documentation for operations staff. Initially, FIDO will be applied for ground systems. Later implementations of FIDO will target spacecraft systems. FIDO is intended to provide system state summary, links to relevant documentation, and suggestions for operator responses to error messages. FIDO will provide the operator with near realtime expert assistance and access to necessary information. This configuration should allow the resolution of many anomalies without the need for on-site intervention by a skilled controller or expert.
    • EUVE Telemetry Processing and Filtering for Autonomous Satellite Instrument Monitoring

      Eckert, M.; Smith, C.; Kronberg, F.; Girouard, F.; Hopkins, A.; Wong, L.; Ringrose, P.; Stroozas, B.; Malina, R. F.; University of California, Berkeley (International Foundation for Telemetering, 1996-10)
      A strategy for addressing the complexity of problem identification and notification by autonomous telemetry monitoring software is discussed. The Extreme Ultraviolet Explorer (EUVE) satellite's science operations center (ESOC) is completing a transition to autonomous operations. Originally staffed by two people, twenty-four hours every day, the ESOC is nearing the end of a phased transition to unstaffed monitoring of the science payload health. To develop criteria for the implementation of autonomous operations we first identified and analyzed potential risk areas. These risk areas were then considered in light of a fully staffed operations model, and in several reduced staffing models. By understanding the accepted risk in the nominal, fully staffed model, we could define what criteria to use in comparing the effectiveness of reduced staff models. The state of the scientific instrument package for EUVE is evaluated by a rule-based telemetry processing software package. In the fully automated implementation, anomalous states are characterized in three tiers: critical to immediate instrument health and safety, non-critical to immediate instrument health and safety, and affecting science data only. Each state requires specific action on the part of the engineering staff, and the response time is determined by the tier. The strategy for implementing this prioritized, autonomous instrument monitoring and paging system is presented. We have experienced a variety of problems in our implementation of this strategy, many of which we have overcome. Problems addressed include: dealing with data dropouts, determining if instrument knowledge is current, reducing the number of times personnel are paged for a single problem, prohibiting redundant notification of known problems, delaying notification of problems for instrument states that do not jeopardize the immediate health of the instrument, assuring a response to problems in a timely manner by engineering staff, and communicating problems and response status among responsible personnel.
    • Data Processing for NASA's TDRSS DAMA Channel

      Long, Christopher C.; New Mexico State University (International Foundation for Telemetering, 1996-10)
      Presently, NASA's Space Network (SN) does not have the ability to receive random messages from satellites using the system. Scheduling of the service must be done by the owner of the spacecraft through Goddard Space Flight Center (GSFC). The goal of NASA is to improve the current system so that random messages, that are generated on board the satellite, can be received by the SN. The messages will be requests for service that the satellites control system deems necessary. These messages will then be sent to the owner of the spacecraft where appropriate action and scheduling can take place. This new service is known as the Demand Assignment Multiple Access system (DAMA).
    • A World Wide Web Interface for Automated Spacecraft Operation

      Kitts, Christopher; Tillier, Clemens; Stanford University (International Foundation for Telemetering, 1996-10)
      A ground based intelligent agent and operations network is being created to handle all aspects of spacecraft command and control. This system will have the dual purpose of enabling cost efficient operation of a number of small satellites and serving as a flexible testbed for the validation of space system autonomy strategies. The system is currently being targeted to include over a dozen globally distributed amateur radio ground stations and access to nearly ten spacecraft. The use of distributed computing systems and virtual interaction schemes are significantly contributing to the creation of this system. The Internet is used to link the network's control centers and ground stations. In addition, a World Wide Web (WWW) based user and operator interface is being developed to permit high level goal specification of spacecraft experiments and actions. This paper will describe the operating network being developed, the use of the Internet as an integral part of the system's architecture, the design of the WWW interface, and the future development of the system.
    • Inexpensive Rate-1/6 Convolutional Decoder for Integration and Test Purposes

      Mengel, Edwin E.; Simpson, Mark E. (International Foundation for Telemetering, 1996-10)
      The Near Earth Asteroid Rendezvous (NEAR) satellite will travel to the asteroid 433 Eros, arriving there early in 1999, and orbit the asteroid for 1 year taking measurements that will map the surface features and determine its elemental composition. NEAR is the first satellite to use the rate-1/6 convolutional encoding on its telemetry downlink. Due to the scarcity and complexity of full decoders, APL designed and built a less capable but inexpensive version of the decoder for use in the integration, test, and prelaunch checkout of the rate-1/6 encoder. This paper describes the rationale for the design, how it works, and the features that are included.
    • The Realization of a Digital Correlation Detector of Telemetry Frame-Synchronization-Pattern Using a Neural Network

      Jun, Zhang; Yi, Qiu; Yan, Du; Qishan, Zhang; Beijing University of Aeronautics & Astronautics (International Foundation for Telemetering, 1996-10)
      In this paper, a method for digital correlation detector that takes advantage of the frame-synchronization-pattern feature of coincidence rate and adopts a multiple-bit detection window is proposed. Based on this method, a new digital correlation detector with a neural network is designed. It can recognizes frame-synchronization-pattern with error bits and slippage bits correctly, which has been approved practically according to the experimental results.
    • Remote Control Multiple Mobile Target System with CDMA

      Zhao, Honglin; Zhao, Xianming; Zhou, Tingxian (International Foundation for Telemetering, 1996-10)
      At present, multiple mobile targets will be remote controlled in many remote control and telemetry system, in which multiple access technology will be applied. This paper proposes a communication scheme to remote control multiple mobile targets using Coded-Division Multiple Access(CDMA) technique. It's feasibility, advantage and shortcoming are analyzed. Moreover, the key techniques of Direct-Sequence Spread Spectrum(DS/SS) system, i.e. the correlation detection and delay lock-on techniques, are studied and stimulated on the experimental model. The results of theoretical analysis show that the CDMA system has the peculiar advantage over the conventional multiple access system, such as FDMA and TDMA.
    • Digital FSK/AM/PM Sub-Carrier Modulator on a 6U-VME-Card

      Hordeski, Theodore J. (International Foundation for Telemetering, 1996-10)
      Aerospace Report No. TOR-0059(6110-01)-3, section 1.3.3 outlines the design and performance requirements of SGLS (Space Ground Link Subsystem) uplink services equipment. This modulation system finds application in the U.S. Air Force satellite uplink commanding system. The SGLS signal generator is specified as an FSK (Frequency Shift Keyed)/AM (Amplitude Modulation)/PM (Phase Modulation) sub-carrier modulator. GDP Space Systems has implemented, on a single 6U-VME card, a SGLS signal generator. The modulator accepts data from several possible sources and uses the data to key one of three FSK tone frequencies. This ternary FSK signal is amplitude modulated by a synchronized triangle wave running at one half the data rate. The FSK/AM signal is then used to phase modulate a tunable HF (High-Frequency) sub-carrier. A digital design approach and the availability of integrated circuits with a high level of functionality enabled the realization of a SGLS signal generator on a single VME card. An analog implementation would have required up to three rack-mounted units to generate the same signal. The digital design improve performance, economy and reliability over analog approaches. This paper describes the advantages of a digital FSK/AM/PM modulation method, as well as DDS (Direct Digital Synthesis) and digital phase-lock techniques.
    • 0-Hz-IF FSK/AM Sub-Carrier Demodulator on a 6U-VME-Card

      Weitzman, Jonathan M.; GDP Space Systems (International Foundation for Telemetering, 1996-10)
      Aerospace Report No. TOR-0059(6110-01)-3, section 1.3.3 outlines the design and performance requirements of SGLS (Space Ground Link Subsystem) services. GDP Space Systems has developed a single card slot FSK (Frequency Shift Keying)/AM (Amplitude Modulation) demodulator. An application of this service is the US Air Force Satellite Command and Ranging System. The SGLS signal is tri-tone-FSK, amplitude modulated by a modified triangle wave at half the data rate. First generation FSK/AM demodulators had poor noise performance because the signal tones were filtered and processed at IF frequencies (65, 76 and 95 kHz). Second generation demodulators suffer from "threshold" due to non-linear devices in the signal path before the primary noise filtering. The GDP Space Systems demodulator uses a 0-Hz- IF topology and avoids both of these shortcomings. In this approach, the signal is first noncoherently down converted to baseband by linear devices, then it is filtered and processed. This paper will discuss the GDP 0-Hz-IF FSK/AM (SGLS) demodulator.
    • Doppler Extraction for a Demand Assignment Multiple Access Service for NASA's Space Network

      Sanchez, Monica A.; New Mexico State University (International Foundation for Telemetering, 1996-10)
      NASA's Space Network (SN) provides both single access (SA) and multiple access (MA) services through a pre-scheduling system. Currently, a user's spacecraft is incapable of receiving service unless prior scheduling occurred with the control center. NASA is interested in efficiently utilizing the time between scheduled services. Thus, a demand assignment multiple access (DAMA) service study was conducted to provide a solution. The DAMA service would allow the user's spacecraft to initiate a service request. The control center could then schedule the next available time slot upon owner approval. In this paper, the basic DAMA service request design and integration is presented.
    • A Small Telemetry System

      Sanzhong, Li; Xianliang, Li; Qishan, Zhang; Affiliation Beijing University of Aero & Astro. (International Foundation for Telemetering, 1996-10)
      A small PCM telemetry system designed for the flight test telemetry task of a new rotorcraft is introduced in this paper. It can provide a flexible frame format which is completely set up by user in advance, to meet the requirements needed in different flight testing phases. In this telemetry system, the data are low in rate and volume but very valuable with stringent quality and transmission accuracy. Data encrypting and channel encoding techniques are employed to guarantee the quality and security of the data. The system architecture based on microprocessors is adopted in order to process the data flexibly. Real-time data processing, monitoring and post-flight analysis are performed by PC type computers. All key components of the system may be programmed. The cost of the total system integration is relatively reduced.
    • Getting The Telemetry Home: How Do You Get Data Back from Titan?

      Mitchell, B. J.; The Johns Hopkins University (International Foundation for Telemetering, 1996-10)
      Exploration of Titan is one of the primary objectives of the Cassini/Huygens mission Saturn due to launch in 1997. Limited data will be provided by Huygens as it descends to the surface via parachute and by Cassini as it orbits Saturn and occasionally passes near Titan. Interest in Titan is high because of its planet-class size, dense atmosphere, and the possibility of continents and seas. Already, there are discussions for a follow-on mission to Titan. There are several proposed designs such as balloons and boats to explore Titan's ethane seas. In all cases, reliable data links back to Earth are absolutely essential. However, simply increasing the power has its limits due to constraints on launch weights. There are a number of possible options for getting data back from Titan. These alternatives, and their effect on the mission profile are discussed.
    • Advanced Range Telemetry (ARTM): Preparing for a New Generation of Telemetry

      Chalfant, Timothy A.; Straehley, Erwin H.; Switzer, Earl R. (International Foundation for Telemetering, 1996-10)
      At open air test and training ranges, telemetry is beset by two opposing forces. One is the inexorable demand to deliver more information to users who must make decisions in ever shorter time frames. The other is the reduced availability of radio frequency spectrum, driven by its increased economic value to society as a whole. ARTM is planned to assure that test and training programs of the next several decades can meet their data quantity and quality objectives in the faces of these challenges. ARTM expects to improve the efficiency of spectrum usage by changing historical methods of acquiring telemetry data and transmitting it from systems under test to range customers. The program is initiating advances in coding, compression, data channel assignment, and modulation. Due to the strong interactions of these four dimensions, the effort is integrated in a single focused program. In that these are problems which are common throughout the test and training community, ARTM is a tri-service program embodying the DoD's Common Test and Training Range Architecture and Reliance principles in its management and organization. This paper will discuss the driving forces, the initial study areas, the organizational structure, and the program goals.
    • Predicting Failures and Estimating Duration of Remaining Service Life from Satellite Telemetry

      Losik, Len; Wahl, Sheila; Owen, Lewis; Lockheed Martin Telemetry & Instrumentation; Lockheed Martin Advanced Technology Center (International Foundation for Telemetering, 1996-10)
      This paper addresses research completed for predicting hardware failures and estimating remaining service life for satellite components using a Failure Prediction Process (FPP). It is a joint paper, presenting initial research completed at the University of California, Berkeley, Center for Extreme Ultraviolet (EUV) Astrophysics using telemetry from the EUV EXPLORER (EUVE) satellite and statistical computation analysis completed by Lockheed Martin. This work was used in identifying suspect "failure precursors." Lockheed Martin completed an exploration into the application of statistical pattern recognition methods to identify FPP events observed visually by the human expert. Both visual and statistical methods were successful in detecting suspect failure precursors. An estimate for remaining service life for each unit was made from the time the suspect failure precursor was identified. It was compared with the actual time the equipment remained operable. The long-term objective of this research is to develop a resident software module which can provide information on FPP events automatically, economically, and with high reliability for long-term management of spacecraft, aircraft, and ground equipment. Based on the detection of a Failure Prediction Process event, an estimate of remaining service life for the unit can be calculated and used as a basis to manage the failure.
    • Telemetry in an Automated Water Supply Control System

      Kilmer, John; White Sands Missile Range (International Foundation for Telemetering, 1996-10)
      The White Sands Missile Range (WSMR) Water Supply Control System (WSCS) controls and monitors the water wells, tanks and booster pumps located at the southern end of the missile range. Figure 1 is an overview of the WSMR water supply system. The WSCS provides water for approximately 90 square miles of the 3,700 square mile missile range. The WSCS was designed and installed in 1990 and in need of upgrading and repair. The system was evaluated and found to be only moderately functional. The WSCS consists of an IBM compatible personal computer (PC) based user interface, located at the WSMR Water Plant and Fire Dept. and industrial-type computers called Programmable Logic Controller (PLC) based stations at the Water Plant, water wells and tanks. The stations communicate over a 400 MHz radio half-duplex link. The serial message utilizes the Cyclic Redundancy Check (CRC) and Block Check Character (BBC) type of error checking. The Master station controls pumping by downloading pump settings to the slave stations. The slave stations upload data to the master such as tank level, pump status, energy usage, gallons of water pumped and various alarms. The system was analyzed and the design was found to be sound. The system did require improvements. These improvements include adding surge suppressors, software upgrades, absolute reading flow rate sensors, and providing adequate environmental cooling for the control system. Procedures for periodic maintenance and calibration of the sensors and schedules for radio equipment maintenance were also developed. Software modifications to reduce WSMR energy usage by reducing pumping during peak energy demand times are being integrated into the WSCS. The peak energy demand times are determined by historical energy usage data.
    • Virtual Cables at the Nevada Test Site

      Khalsa, N. S.; Bechtel (International Foundation for Telemetering, 1996-10)
      Shrinking budgets and labor pools have impacted our ability to perform experiments at the Nevada Test Site (NTS) as we did previously. Specifically, we could no longer run heavy cables to remote data acquisition sites, so we replaced the cables with RF links that were transparent to the existing system, as well as being low-cost and easy to deploy. This paper details how we implemented the system using mostly commercial off-the-shelf components.
    • Flexible Intercom System Design for Telemetry Sites and Other Test Environments

      Bougan, Timothy B.; Science Applications International Corporation (International Foundation for Telemetering, 1996-10)
      Testing avionics and military equipment often requires extensive facilities and numerous operators working in concert. In many cases these facilities are mobile and can be set up at remote locations. In almost all situations the equipment is loud and makes communication between the operators difficult if not impossible. Furthermore, many sites must transmit, receive, relay, and record telemetry signals. To facilitate communication, most telemetry and test sites incorporate some form of intercom system. While intercom systems themselves are a not a new concept and are available in many forms, finding one that meets the requirements of the test community (at a reasonable cost) can be a significant challenge. Specifically, the test director must often communicate with several manned stations, aircraft, remote sites, and/or simultaneously record all or some of the audio traffic. Furthermore, it is often necessary to conference all or some of the channels (so that all those involved can fully follow the progress of the test). The needs can be so specialized that they often demand a very expensive "custom" solution. This paper describes the philosophy and design of a multi-channel intercom system specifically intended to support the needs of the telemetry and test community. It discusses in detail how to use state-of-the-art field programmable gate arrays, relatively inexpensive computers and digital signal processors, and some other new technologies to design a fully digital, completely non-blocking intercom system. The system described is radically different from conventional designs but is much more cost effective (thanks to recent developments in programmable logic, microprocessor performance, and serial/digital technologies). This paper presents, as an example, the conception and design of an actual system purchased by the US government.
    • The Role of Standards in COTS Integration Projects

      Stottlemyer, Alan R.; Hassett, Kevin M. (International Foundation for Telemetering, 1996-10)
      We have long used standards to guide the development process of software systems. Standards such as POSIX, X-Windows, SQL have become part of the language of software developers and have guided the coding of systems that are intended to be portable and interoperable. Standards also have a role to play in the integration of commercial off-the-shelf (COTS) products. At NASA's Goddard Space Flight Center, we have been participating on the Renaissance Team, a reengineering effort that has seen the focus shift from custom-built systems to the use of COTS to satisfy prime mission functions. As part of this effort, we developed a process that identified standards that are applicable to the evaluation and integration of products and assessed how those standards should be applied. Since the goal is to develop a set of standards that can be used to instantiate systems of differing sizes and capabilities, the standards selected have been broken into four areas: global integration standards, global development standards, mission development standards, and mission integration standards. Each of the areas is less restrictive than the preceding area in the standards that are allowed. This paper describes the process that we used to select and categorize the standards to be applied to Renaissance systems.
    • Realize Configurable and Interoperable TT&C with Commercial Components

      Patel, Kirti; Space System/Loral (International Foundation for Telemetering, 1996-10)
      With explosive growth in the satellite communication market. there is an increasing need for the satellite network service providers to support many satellites with a common Telemetry, Tracking, and Commanding (TT&C) assets. The open bus technology, and Commercial Off The Shelf (COTS) Hardware and Software components, provides an opportunity to build a common IF and baseband systems that will support many satellites with different frequencies and protocols. However, the high frequency front end components of the ground station such as antenna or HPA can not be common due to different gain and polarization requirements of the various communication bands and frequencies. The system architecture presented in this paper offers such system that is interoperable and reconfigurable in near real-time to support multiple frequency and multiple communication protocols.
    • IMACCS: A Progress Report on NASA/GSFC's COTS-Based Ground Data Systems, and Their Extension into New Domains

      Scheidker, E. J.; Pendley, R. D.; Rashkin, R. M.; Weking, R. D.; Cruse, B. G.; Bracken, M. A.; CSC; Altair Aerospace; NASA GSFC (International Foundation for Telemetering, 1996-10)
      The Integrated Monitoring, Analysis, and Control COTS System (IMACCS), a system providing real time satellite command and telemetry support, orbit and attitude determination, events prediction, and data trending, was implemented in 90 days at NASA Goddard Space Flight Center (GSFC) in 1995. This paper describes upgrades made to the original commercial, off-the-shelf (COTS)-based prototype. These upgrades include automation capability and spacecraft Integration and Testing (I&T) capability. A further extension to the prototype is the establishment of a direct RF interface to a spacecraft. As with the original prototype, all of these enhancements required lower staffing levels and reduced schedules compared to custom system development approaches. The team's approach to system development, including taking advantage of COTS and legacy software, is also described.