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Briefs: Information Technology
An improved method of model-based diagnosis of a complex engineering system is embodied in an algorithm that involves considerably less computation than do prior such algorithms. This...
Briefs: Information Technology
A computationally efficient method has been developed to enable optimization of the placement of sensors for the purpose of diagnosis of a complex engineering system (e.g., an aircraft or...
Briefs: Information Technology
Truncation Depth Rule-of-Thumb for Convolutional Codes
In this innovation, it is shown that a commonly used rule of thumb (that the truncation depth of a convolutional code should be five times the memory length, m, of the code) is accurate only for rate 1/2 codes. In fact, the truncation depth should be 2.5 m/(1 – r), where r is the code rate....
Briefs: Photonics/Optics
A proposed metrology system would be incorporated into a proposed telescope that would include focusing optics on a rigid bench connected via a deployable mast to another rigid bench...
Briefs: Physical Sciences
Formation Flying of Components of a Large Space Telescope
A conceptual space telescope having an aperture tens of meters wide and a focal length of hundreds of meters would be implemented as a group of six separate optical modules flying in formation: a primary-membrane-mirror module, a relay-mirror module, a focal-plane-assembly module containing...
Briefs: Photonics/Optics
Laser Metrology Heterodyne Phase-Locked Loop
A method reduces sensitivity to noise in a signal from a laser heterodyne interferometer. The phase-locked loop (PLL) removes glitches that occur in a zero-crossing detector's output [that can happen if the signal-to-noise ratio (SNR) of the heterodyne signal is low] by the use of an internal oscillator...
Briefs: Photonics/Optics
Crystalline whispering gallery mode resonators (CWGMRs) made of crystals with axial symmetry have ordinary and extraordinary families of optical modes. These modes have substantially...
Briefs: Photonics/Optics
Spatial Modulation Improves Performance in CTIS
Suitably formulated spatial modulation of a scene imaged by a computed-tomography imaging spectrometer (CTIS) has been found to be useful as a means of improving the imaging performance of the CTIS. As used here, “spatial modulation” signifies the imposition of additional, artificial structure on...
Briefs: Energy
Oxide Fiber Cathode Materials for Rechargeable Lithium Cells
LiCoO2 and LiNiO2 fibers have been investigated as alternatives to LiCoO2 and LiNiO2 powders used as lithium-intercalation compounds in cathodes of rechargeable lithium-ion electrochemical cells. In making such a cathode, LiCoO2 or LiNiO2 powder is mixed with a binder [e.g.,...
Briefs: Green Design & Manufacturing
Electromagnetically Clean Solar Arrays
The term “electromagnetically clean solar array” (EMCSA) refers to a panel that contains a planar array of solar photovoltaic cells. The cells are laminated with shielding, narrow-current-loop wiring, and structural supports. EMCSAs could be useful in applications that require limited electromagnetic interference.
Briefs: Green Design & Manufacturing
System for Removing Pollutants From Incinerator Exhaust
A system for removing pollutants — primarily sulfur dioxide and mixed oxides of nitrogen (NOx) — from incinerator exhaust has been demonstrated. The system is also designed secondarily to remove particles, hydrocarbons, and CO. The system is intended for use in an enclosed environment, for...
Briefs: Imaging
The crew activity analyzer (CAA) is a system of electronic hardware and software for automatically identifying patterns of group activity among crew members working together in an office, cockpit, workshop, laboratory, or...
Briefs: Software
Distributing Data to Hand-Held Devices in a Wireless Network
ADROIT is a developmental computer program for real-time distribution of complex data streams for display on Web-enabled, portable terminals held by members of an operational team of a spacecraft-command- and-control center who may be located away from the center. Examples of such...
Briefs: Information Technology
A method of incorporating information, acquired by a multibeam laser or radar altimeter system, pertaining to the distance and direction between the system and a nearby target...
Briefs: Information Technology
MODIS Atmospheric Data Handler
A number of science data sets are derived from the observations of the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument onboard NASA’s Terra and Aqua satellites. These data typically contain information on retrieval techniques, quality-control flags, and geo-referencing information. These datasets,...
Briefs: Information Technology
Reducing Surface Clutter in Cloud Profiling Radar Data
An algorithm has been devised to reduce ground clutter in the data products of the CloudSat Cloud Profiling Radar (CPR), which is a nadir-looking radar instrument, in orbit around the Earth, that measures power backscattered by clouds as a function of distance from the instrument. Ground...
Briefs: Imaging
Advanced Land Imager Assessment System
The Advanced Land Imager Assessment System (ALIAS) supports radiometric and geometric image processing for the Advanced Land Imager (ALI) instrument onboard NASA’s Earth Observing-1 (EO-1) satellite. ALIAS consists of two processing subsystems for radiometric and geometric processing of the ALI’s...
Briefs: Semiconductors & ICs
Prototype logic gates made of n-channel junction field-effect transistors (JFETs) and epitaxial resistors have been demonstrated, with a view toward eventual implementation of digital...
Briefs: Imaging
Delivering Images for Mars Rover Science Planning
A methodology has been developed for delivering, via the Internet, images transmitted to Earth from cameras on the Mars Explorer Rovers, the Phoenix Mars Lander, the Mars Science Laboratory, and the Mars Reconnaissance Orbiter spacecraft. The images in question are used by geographically dispersed...
Briefs: Electronics & Computers
Spaceborne Hybrid-FPGA System for Processing FTIR Data
Progress has been made in a continuing effort to develop a spaceborne computer system for processing readout data from a Fourier-transform infrared (FTIR) spectrometer to reduce the volume of data transmitted to Earth. The approach followed in this effort, oriented toward reducing design time...
Briefs: Electronics & Computers
FPGA Coprocessor for Accelerated Classification of Images
An effort related to that described in the preceding article focuses on developing a spaceborne processing platform for fast and accurate onboard classification of image data, a critical part of modern satellite image processing. The approach again has been to exploit the versatility of...
Briefs: Electronics & Computers
SiC JFET Transistor Circuit Model for Extreme Temperature Range
A technique for simulating extreme-temperature operation of integrated circuits that incorporate silicon carbide (SiC) junction field-effect transistors (JFETs) has been developed. The technique involves modification of NGSPICE, which is an open-source version of the popular Simulation...
Briefs: Electronics & Computers
In an alternative to a prior technique of time-domain- reflectometry (TDR) in which very short excitation pulses are used, the pulses have very short rise and fall times and the pulse...
Briefs: Electronics & Computers
Update on Development of SiC Multi-Chip Power Modules
Progress has been made in a continuing effort to develop multi-chip power modules (SiC MCPMs). This effort at an earlier stage was reported in “SiC Multi-Chip Power Modules as Power-System Building Blocks” (LEW-18008-1), NASA Tech Briefs, Vol. 31, No. 2 (February 2007), page 28.
Briefs: Electronics & Computers
Radio Ranging System for Guidance of Approaching Spacecraft
A radio communication and ranging system has been proposed for determining the relative position and orientations of two approaching spacecraft to provide guidance for docking maneuvers. On Earth, the system could be used similarly for guiding approaching aircraft and for automated...
Briefs: Electronics & Computers
Improved Short-Circuit Protection for Power Cells in Series
A scheme for protection against short circuits has been devised for series strings of lithium electrochemical cells that contain built-in short-circuit protection devices, which go into a high-resistance, current-limiting state when heated by excessive current. If cells are simply...
Briefs: Electronics & Computers
Communication Limits Due to Photon-Detector Jitter
A theoretical and experimental study was conducted of the limit imposed by photon-detector jitter on the capacity of a pulse-position- modulated optical communication system in which the receiver operates in a photon-counting (weak-signal) regime. Photon-detector jitter is a random delay between...
Briefs: Electronics & Computers
Electromagnetically Clean Solar Arrays
The term “electromagnetically clean solar array” (“EMCSA”) refers to a panel that contains a planar array of solar photovoltaic cells and that, in comparison with a functionally equivalent solar-array panel of a type heretofore used on spacecraft, (1) exhibits less electromagnetic interference to and...
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