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At least 1,423 records · Page 79

Reconfigurable redundancy management for aircraft flight control

A highly fault tolerant digital computer system has been configured based on extensive experience with flight proven, redundant digital flight control systems. The feasibility of minimizing hardware complexity is shown while maintaining high levels of fault tolerance. The emerging hardware design combines reconfiguration concepts with conventional hardware redundancy techniques and special operational software to provide dual fail operate performance with a basic triplex system. The design provides high reliability and flight safety, enhances maintainability, and reduces life cycle cost while offering improved performance for future aircraft.

Bosch, J. A.↗

Satellite onboard feature classification using CCD's

In this paper discrete time analog signal processing applications of CCD's are discussed. The types of computations which can be performed in the CCD technology are discussed and compared with respect to their accuracy and required support hardware. The classification problem encountered in the reduction of multispectral data into features of terrestrial interest are decomposed into a CCD technology based hardware solution. The resulting system is readily implemented with existing and anticipated CCD devices. This system will be projected to spacecraft application.

Benz, H. F.↗

A technique for real-time data preprocessing

A processing system is presented that implements simultaneously the efficiency of the special-purpose processor and the total applicability of the general-purpose computer - characteristics commonly thought of as being mutually exclusive. The solution adopted is that of specializing the machine by programming the hardware structure, rather than by adding software systems to it. Data are organized in circulating pages which form a plurality of local dynamic memories for each process. Programs are made up of modules, each describing a transient special-purpose machine. Applications to real-time processing of radar signals are referred to.

Schaffner, M. R.↗

A multi-microprocessor system for finite element structural analysis

During the last few years, advances in microprocessor technology have spurred a renewed interest in special-purpose computers. The microprocessor has become small, inexpensive, and powerful enough to be considered as a building block for special-purpose hardware. A description is presented of the architecture of a prototype 'finite element machine' currently being built. Attention is given to details regarding the finite element analysis problem, the arrangement of the processors as finite element nodes in the structural model, the influence of the architecture on the solution algorithm, interprocessor communication primitives, and the performance of the finite element machine.

Jordan, H. F.↗

As-built design specification of the data order processor ORDHDT

A description and subroutine documentation of the data order processor, ORHDT is given. As part of the LANDSAT imagery verification and extraction system, ORDHT creates a computer tape containing the AgRISTARS requirements for LANDSAT data to be ordered from Goddard Space Flight Center. A brief description of hardware requirements is also included.

Rios, A.↗

ARTS BETA testing report

The advanced real time system (ARTS) was tested utilizing existing commercial system hardware and software which has been operating under advanced operating system (AOS) for several years in a multitasking, multiprocessing, and multiple computer environment. Experiences with ARTS in terms of compatibility with AOS, ease of transmission between AOS and ARTS, and functional areas of ARTS which were tested are discussed. Relative and absolute performance of ARTS versus AOS as measured in the system environment are also presented.

Mccune, M. C.↗

Field interface module software description

The software for the field interface module (FIM) is designed to fully optimize the hardware capabilities of the FIM. Software routines exist which enable the FIM to monitor data, control components, communicate with an uplink computer, and perform real-time and local self-diagnostics. The FIM program is not dependent upon any particular uplink computer and is adaptable to various applications with a miniumum of modifications.

Valtier, H.↗

Development and evaluation of a fault-tolerant multiprocessor (FTMP) computer. Volume 4: FTMP executive summary

The FTMP architecture is a high reliability computer concept modeled after a homogeneous multiprocessor architecture. Elements of the FTMP are operated in tight synchronism with one another and hardware fault-detection and fault-masking is provided which is transparent to the software. Operating system design and user software design is thus greatly simplified. Performance of the FTMP is also comparable to that of a simplex equivalent due to the efficiency of fault handling hardware. The FTMP project constructed an engineering module of the FTMP, programmed the machine and extensively tested the architecture through fault injection and other stress testing. This testing confirmed the soundness of the FTMP concepts.

Smith, T. B., III↗

MIDAS - A microcomputer-based image display and analysis system with full Landsat frame processing capabilities

Image Display and Analysis Systems (MIDAS) developed at NASA/Ames for the analysis of Landsat MSS images is described. The MIDAS computer power and memory, graphics, resource-sharing, expansion and upgrade, environment and maintenance, and software/user-interface requirements are outlined; the implementation hardware (including 32-bit microprocessor, 512K error-correcting RAM, 70 or 140-Mbyte formatted disk drive, 512 x 512 x 24 color frame buffer, and local-area-network transceiver) and applications software (ELAS, CIE, and P-EDITOR) are characterized; and implementation problems, performance data, and costs are examined. Planned improvements in MIDAS hardware and design goals and areas of exploration for MIDAS software are discussed.

Hofman, L. B.↗

Putting the 'super' in supercomputers

Computers used for numerical simulations of physical phenomena, e.g., flowfields, meteorology, structural analysis, etc., replace physical experiments that are too expensive or impossible to perform. The problems considered continually become increasingly more complex and thus demand faster processing times to do all necessary computations. The effects components technologies have on computer speed are leveling off, leaving new architectures and programming as the only currently viable means to upgrade speed. Parallel computations, either in the form of array processors, assembly line processing or multiprocessors are being explored using existing microprocessor technologies. Slower hardware configurations can also be made equivalent to faster supercomputers by economic programming. The availability of rudimentary parallel architecture supercomputers for general industrial use is increasing. Scientific applications continue to drive the development of more sophisticated parallel machines.

Schulbach, C.↗

The Venus radar mapper spacecraft design

This paper discusses the driving mission requirements on the VRM spacecraft, the resulting design, and the spacecraft performance capabilities. The spacecraft design is driven by fine pointing requirements for radar mapping resolution, by extremes of thermal environment in the Venus orbit, and by high instrument power requirements. The spacecraft design emphasized use of as much existing hardware and software as possible to meet the cost constraints. Existing design was used where hardware was not already available. The VRM spacecraft utilizes the spare Voyager High Gain Antenna (HGA) and equipment bus, the Galileo computers and power conditioning equipment, and Mariner Medium Gain Antenna (MGA). Further cost savings were possible by using the HGA for both radar mapping at S-band frequency and high rate data playback at X-band frequency. The use of the Star 48 B solid rocket motor for VOI reduced propulsion system cost and complexity. The design tradeoffs that led to the VRM spacecraft configuration and the performance capabilities of the spacecraft are summarized for each subsystem.

Gamber, T.↗

Doppler lidar studies of atmospheric wind field dynamics

For the past 5 years the Wave Propagation Lab. has operated a pulsed CO2 Doppler lidar system to evaluate coherent laser radar technology and to investigate applications of the technique in atmospheric research. The capability of the system to provide measurements of atmospheric winds, backscatter, and water vapor has been extensively studied over this period. Because Doppler lidar can measure atmospheric wind structure in the clear air without degradation by terrain features, it offers a unique capability as a research tool for studies of many transient or local scale atmospheric events. This capability was demonstrated in recent field experiments near Boulder, Colo. and Midland, Tex., in which the lidar clearly depicted the wind field structure associated with several types of phenomena, including thunderstorm microbursts, valley drainage flow, and passage of a dryline front. To improve sensitivity during the periods of low aerosol backscatter, the system has recently been upgraded with new transmitter/receiver hardware. The upgraded system, which transmit 2 J per pulse of output energy at a rate of 50 Hz and incorporates computer control for automated operation, underwent calibration testing during the spring of 1986.

Hardesty, R. M.↗

Knowledge representation and user interface concepts to support mixed-initiative diagnosis

The Remote Maintenance Monitoring System (RMMS) provides automated support for the maintenance and repair of ModComp computer systems used in the Launch Processing System (LPS) at Kennedy Space Center. RMMS supports manual and automated diagnosis of intermittent hardware failures, providing an efficient means for accessing and analyzing the data generated by catastrophic failure recovery procedures. This paper describes the design and functionality of the user interface for interactive analysis of memory dump data, relating it to the underlying declarative representation of memory dumps.

Sobelman, Beverly H.↗

A parallel-pipelined architecture for a multi carrier demodulator

Analog devices have been used for processing the information on board the satellites. Presently, digital devices are being used because they are economical and flexible as compared to their analog counterparts. Several schemes of digital transmission can be used depending on the data rate requirement of the user. An economical scheme of transmission for small earth stations uses single channel per carrier/frequency division multiple access (SCPC/FDMA) on the uplink and time division multiplexing (TDM) on the downlink. This is a typical communication service offered to low data rate users in commercial mass market. These channels usually pertain to either voice or data transmission. An efficient digital demodulator architecture is provided for a large number of law data rate users. A demodulator primarily consists of carrier, clock, and data recovery modules. This design uses principles of parallel processing, pipelining, and time sharing schemes to process large numbers of voice or data channels. It maintains the optimum throughput which is derived from the designed architecture and from the use of high speed components. The design is optimized for reduced power and area requirements. This is essential for satellite applications. The design is also flexible in processing a group of a varying number of channels. The algorithms that are used are verified by the use of a computer aided software engineering (CASE) tool called the Block Oriented System Simulator. The data flow, control circuitry, and interface of the hardware design is simulated in C language. Also, a multiprocessor approach is provided to map, model, and simulate the demodulation algorithms mainly from a speed view point. A hypercude based architecture implementation is provided for such a scheme of operation. The hypercube structure and the demodulation models on hypercubes are simulated in Ada.

Kwatra, S. C.↗

Fault tolerance in onboard processors - Protecting efficient FDM demultiplexers

The application of convolutional codes to protect demultiplexer filter banks is demonstrated analytically for efficient implementations. An overview is given of the parameters for the efficient implementations of filter banks, and real convolutional codes are discussed in terms of DSP operations. Methods for composite filtering and parity generation are outlined, and attention is given to the protection of polyphase filter demultiplexing systems. Real convolutional codes can be applied to protect demultiplexer filter banks by employing two forms of low-rate parity calculation to each filter bank. The parity values are computed either by the output with an FIR parity filter or in parallel with the normal processing by a composite filter. Hardware similarities between the filter bank and the main demultiplexer bank permit efficient redeployment of the processing resources to the main processing function in any configuration.

Redinbo, Robert↗

An evaluation of software tools for the design and development of cockpit displays

The use of all-glass cockpits at the NASA Langley Research Center (LaRC) simulation facility has changed the means of design, development, and maintenance of instrument displays. The human-machine interface has evolved from a physical hardware device to a software-generated electronic display system. This has subsequently caused an increased workload at the facility. As computer processing power increases and the glass cockpit becomes predominant in facilities, software tools used in the design and development of cockpit displays are becoming both feasible and necessary for a more productive simulation environment. This paper defines LaRC requirements of a display software development tool and compares two available applications against these requirements. As a part of the software engineering process, these tools reduce development time, provide a common platform for display development, and produce exceptional real-time results.

Ellis, Thomas D., Jr.↗

STS-103 Crew Training

The Hubble Space Telescope (HST) team is preparing for NASA's third scheduled service call to Hubble. This mission, STS-103, will launch from Kennedy Space Center aboard the Space Shuttle Discovery. The seven flight crew members are Commander Curtis L. Brown, Pilot Scott J. Kelly, European Space Agency (ESA) astronaut Jean-Francois Clervoy who will join space walkers Steven L. Smith, C. Michael Foale, John M. Grunsfeld, and ESA astronaut Claude Nicollier. The objectives of the HST Third Servicing Mission (SM3A) are to replace the telescope's six gyroscopes, a Fine-Guidance Sensor, an S-Band Single Access Transmitter, a spare solid-state recorder and a high-voltage/temperature kit for protecting the batteries from overheating. In addition, the crew plans to install an advanced computer that is 20 times faster and has six times the memory of the current Hubble Space Telescope computer. To prepare for these extravehicular activities (EVAs), the SM3A astronauts participated in Crew Familiarization sessions with the actual SM3A flight hardware. During these sessions the crew spent long hours rehearsing their space walks in the Guidance Navigation Simulator and NBL (Neutral Buoyancy Laboratory). Using space gloves, flight Space Support Equipment (SSE), and Crew Aids and Tools (CATs), the astronauts trained with and verified flight orbital replacement unit (ORU) hardware. The crew worked with a number of trainers and simulators, such as the High Fidelity Mechanical Simulator, Guidance Navigation Simulator, System Engineering Simulator, the Aft Shroud Door Trainer, the Forward Shell/Light Shield Simulator, and the Support Systems Module Bay Doors Simulator. They also trained and verified the flight Orbital Replacement Unit Carrier (ORUC) and its ancillary hardware. Discovery's planned 10-day flight is scheduled to end with a night landing at Kennedy.

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