March 2001

A technique of partial subtractive dither has been developed to improve the performance of any of a variety of near-lossless data-compression algorithms. The technique may be applicable...

Briefs: Electronics & Computers
Acquisition, Tracking, and Pointing in Optical Communication

A document in the form of lecture slides outlines a program of development of capabilities for acquisition of signals, tracking of signal sources, and pointing of transmitters and receivers in deep-space optical communications. Topics addressed on the first few slides include the...

Briefs: Information Technology
Software for Preprocessing of Raw SAR Data

The SAR Processing System Raw Data Processor (SPS RDS) computer program is used in the Alaska SAR Facility (ASF) to scan and decode raw data that have been downlinked from the European Remote Sensing Satellite (ERS), the Japanese Earth Resources Satellite (JERS), and the RADARSAT (a Canadian...

In a scheme to increase the overall data return from a phase-modulation, suppressed-carrier telemetry transmitter, the telemetry playback symbol rate is adjusted essentially...

Briefs: Information Technology
Software for Locating Heterogeneous Data in Different Places

The Object Oriented Data Technology group at NASA's Jet Propulsion Laboratory is developing software for locating data — especially scientific data — stored in various formats on heterogeneous computer systems at different locations. The software is intended to exploit and extend...

Figure 1 depicts an apparatus that simultaneously and synchronously records magnified ordinary top-view video images and laser-shadowgraph video images of a sessile...

Briefs: Electronics & Computers
Improved Encryption-Mode GPS Receiver

An improved Global Positioning System (GPS) receiver, which processes an encrypted P-code signal without knowledge of the encryption code (denoted here as A-codeless mode), includes an auxiliary antenna...

Briefs: Electronics & Computers
Low-Power, Sparse-Sampling GPS Receiver

The term "microGPS" denotes a Global Positioning System (GPS) receiver design concept that combines relatively simple, lightweight, low-power-consumption hardware with portable, efficient software. The power demand of a microGPS receiver can be made low because it is designed to sample sparsely; that is,...

Briefs: Software
Software Models Spacecraft Dynamics and Space Environment

The Spacecraft Control Toolbox (SCT) helps design control systems and attitude estimators, analyze station-keeping requirements, generate fuel and pointing budgets, and analyze spacecraft dynamics. The SCT provides a comprehensive set of over five hundred functions including:

Briefs: Software
Web-Based Software for Distributed Planning

The RecDel System is a low-cost software application that helps different groups of a complex project negotiate interfaces between interdependent schedules. The RecDel system is based on a concept of distributed planning, wherein the cognizant persons retain control over, and responsibility for, their...

Briefs: Software
Software for Detecting Tones in Beacon Monitoring

A software package for use in a ground receiving station detects a beacon-monitor tone transmitted by a spacecraft. To recapitulate from previous NASA Tech Briefs articles on beacon monitoring: An onboard computer processes data from onboard sensors to summarize the condition of the spacecraft...

Briefs: Software
Automated Real-Time Spacecraft Navigation System

The Automated Real-Time Spacecraft Navigation (ARTSN) system is a prototype of a class of software systems for automated navigation and monitoring of spacecraft from stations on the Earth. The system processes radio metric tracking data (principally, range and Doppler measurements) in real time to...

Metal-supported catalyst beds with improved thermal and flow characteristics for promoting endothermic chemical reactions are undergoing development. In the proposed original...

In catalytic flow-through chemical reactors being explored for space vehicle applications, the catalysts would be supported on the surfaces of wires, instead of on particles, as are typically used...

In an extension of the concept reported in the preceding article, catalytic flow-through chemical reactors of a proposed type would contain catalyst-coated microtubes, possibly in combination...

Extensive redundancy is designed into aircraft flight-control systems to ensure a low probability of failure. During recent years, however, major failures of flight-control systems...

An arc-welding technique for repair of a directionally solidified (DS) nickel-base superalloy article (e.g., a turbine blade or vane) has been devised. The technique equally is...

A field-reversed configuration (FRC) has been proposed for a magnetic mirror — a solenoidal electromagnet configured and operated in such a way as to effect at least partial...

Briefs: Physical Sciences
Updated Multidisciplinary Optical-System-Analysis Software

Version 5.0 of the Integrated Modeling of Optical Systems (IMOS) software has been released. A previous version was described in "Software for Multidisciplinary Analysis of Optical Systems" (NPO-20536), NASA Tech Briefs, Vol. 24, No. 11 (November 2000), page 36. In both versions, IMOS...

The NASA Dryden DC-8 Airborne Science Laboratory (see Figure 1) performs research around the globe, recently in support of the SAGE III Ozone Loss and Validation Experiment (SOLVE). This...

Briefs: Information Technology
Wavelet Analysis To Predict Limit Cycles

A method to predict the onset of a limit cycle for an aeroelastic testbed has been developed. The prediction is based on wavelet processing of measurement data that have been recorded under various...

Infrared (IR) sensors of a proposed type, and integrated-circuit imaging devices containing planar arrays of such sensors, would be based on a combination of (1)...

A proposed complementary metal oxide/semiconductor (CMOS) integrated-circuit imaging device of the active-pixel sensor (APS) type is capable of simultaneously generating the pixel-by-pixel...

Briefs: Electronics & Computers
Software for Analyzing Telecommunication Link Performance

The Telecom Forecaster Predictor (TFP) is a multi-mission computer program for analyzing deep space telecommunication links. Analysts use the TFP for link planning, performance prediction, and post-pass trending analysis. For each mission, multiple users access a controlled set of TFP...

Integrated-circuit imaging devices of a proposed type would contain planar arrays of microscopic sensors that would exploit giant magnetoresistance (GMR). Each GMR sensor in such a...

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