Tech Briefs

Processing Raw HST Data With Up-to-Date Calibration Data

On-the-Fly Reprocessing (OTFR) is a collection of data-processing routines that work within the context of the Hubble Space Telescope (HST) pipeline data-flow system. The purpose served by OTFR is to generate, on demand, scientifically useful data products from raw HST data stored in an archive. First, on the basis of the requested final data products, OTFR retrieves the corresponding sets of raw data from the archives. Next, OTFR processes the raw data sets to remove artifacts and to establish proper header and other template information. Finally, the calibration routines appropriate to the specific data sets are invoked to produce the requested data products, and the data products are released to an archive distribution system for transmission to the requesting party. OTFR offers two notable advantages: (1) Inasmuch as calibrated data occupy about 8 times as much storage space as do raw data, by obviating storage of calibrated data, OTFR reduces the storage capacity needed by the archive; and (2) the calibration routines can be updated to give requesters the benefit of the most recent calibrations.

Posted in: Briefs, Electronics & Computers, Calibration, Architecture, Data management

System for Secure Integration of Aviation Data

Data can be analyzed without compromising security or anonymity.

The Aviation Data Integration System (ADIS) of Ames Research Center has been established to promote analysis of aviation data by airlines and other interested users for purposes of enhancing the quality (especially safety) of flight operations. The ADIS is a system of computer hardware and software for collecting, integrating, and disseminating aviation data pertaining to flights and specified flight events that involve one or more airline(s). The ADIS is secure in the sense that care is taken to ensure the integrity of sources of collected data and to verify the authorizations of requesters to receive data. Most importantly, the ADIS removes a disincentive to collection and exchange of useful data by providing for automatic removal of information that could be used to identify specific flights and crew members. Such information, denoted sensitive information, includes flight data (here signifying data collected by sensors aboard an aircraft during flight), weather data for a specified route on a specified date, date and time, and any other information traceable to a specific flight. The removal of information that could be used to perform such tracing is called “de-identification.”

Posted in: Briefs, Electronics & Computers, Failure analysis, Computer software and hardware, Aircraft operations, Data management, Identification

Mobile Collection and Automated Interpretation of EEG Data

Diagnoses could be performed while subjects engaged in ordinary activities.

A system that would comprise mobile and stationary electronic hardware and software subsystems has been proposed for collection and automated interpretation of electroencephalo- graphic (EEG) data from subjects in everyday activities in a variety of environments. By enabling collection of EEG data from mobile subjects engaged in ordinary activities (in contradistinction to collection from immobilized subjects in clinical settings), the system would expand the range of options and capabilities for performing diagnoses.

Posted in: Briefs, TSP, Bio-Medical, Medical, Computer software and hardware, Data acquisition and handling, Sensors and actuators, Diagnosis, Nervous system, Test equipment and instrumentation

Servomotor and Controller Having Large Dynamic Range

A lightweight, compact, mechanically simple system offers high performance.

A recently developed micro-commanding rotational position control system offers advantages of less mechanical complexity, less susceptibility to mechanical resonances, less power demand, less bulk, less weight, and lower cost, relative to prior rotational position control systems based on stepping motors and gear drives. This system includes a digital signal processor (DSP)-based electronic controller, plus a shaft-angle resolver and a servomotor mounted on the same shaft. Heretofore, micro-stepping has usually been associated with stepping motors, but in this system, the servomotor is micro-commanded in response to rotational-position feedback from the shaft-angle resolver.

Posted in: Briefs, Electronics & Computers, Stability control, Downsizing, Electronic control systems, Performance upgrades, Product development

Digital Multicasting of Multiple Audio Streams

Authorized listeners can hear any or all streams in nearly real time.

The Mission Control Center Voice Over Internet Protocol (MCC VOIP) system (see figure) comprises hardware and software that effect simultaneous, nearly real-time transmission of as many as 14 different audio streams to authorized listeners via the MCC intranet and/or the Internet. The original version of the MCC VOIP system was conceived to enable flight-support personnel located in offices outside a spacecraft mission control center to monitor audio loops within the mission control center. Different versions of the MCC VOIP system could be used for a variety of public and commercial purposes — for example, to enable members of the general public to monitor one or more NASA audio streams through their home computers, to enable air-traffic supervisors to monitor communication between airline pilots and air-traffic controllers in training, and to monitor conferences among brokers in a stock exchange.

Posted in: Briefs, Electronics & Computers, Audio equipment, Computer software and hardware, Internet, Telecommunications systems

Simplified Generation of High-Angular-Momentum Light Beams

Inherent properties of a WGM resonator and optical fiber are exploited.

A simplified method of generating a beam of light having a relatively high value of angular momentum (see figure) involves the use of a compact apparatus consisting mainly of a laser, a whispering gallery mode (WGM) resonator, and optical fibers. The method also can be used to generate a Bessel beam. (“Bessel beam” denotes a member of a class of non-diffracting beams, so named because their amplitudes are proportional to Bessel functions of the radii from their central axes. High-order Bessel beams can have high values of angular momentum.)

Posted in: Briefs, TSP, Physical Sciences, Amplifiers, Fiber optics, Lasers, Production

Complex Type-II Interband Cascade MQW Photodetectors

Multiple active subregions, each optimized for a different color, would enable multicolor operation.

Multiple-quantum-well (MQW) photodetectors of a proposed type would contain active regions comprising multiple superlattice subregions. These devices would have complex structures: The superlattice of each subregion would be designed for enhanced absorption of photons in a desired wavelength band (typically in the infrared) and multiple subregions of different design would be cascaded for multicolor operation.

Posted in: Briefs, TSP, Physical Sciences, Architecture, Lasers, Product development

Interferometric Quantum-Nondemolition Single-Photon Detectors

These detectors would function independently of frequency.

Two interferometric quantum-nondemolition (QND) devices have been proposed: (1) a polarization- independent device and (2) a polarization- preserving device. The prolarization- independent device works on an input state of up to two photons, whereas the polarization- preserving device works on a superposition of vacuum and single-photon states. The overall function of the device would be to probabilistically generate a unique detector output only when its input electromagnetic mode was populated by a single photon, in which case its output mode would also be populated by a single photon.

Posted in: Briefs, TSP, Physical Sciences, Electromagnetic compatibility, Semiconductor devices

Ring-Down Spectroscopy for Characterizing a CW Raman Laser

Parameters of operation can be obtained from a single ringdown scan.

A relatively simple technique for characterizing an all-resonant intracavity continuous- wave (CW) solid-state Raman laser involves the use of ring-down spectroscopy. As used here, “characterizing” signifies determining such parameters as threshold pump power, Raman gain, conversion efficiency, and quality factors (Q values) of the pump and Stokes cavity modes.

Posted in: Briefs, TSP, Physical Sciences, Lasers, Spectroscopy, Performance tests, Test procedures

Imaging Spectrometer on a Chip

One integrated circuit would perform the functions of a conventional several-kilogram spectrometer.

A proposed visible-light imaging spectrometer on a chip would be based on the concept of a heterostructure comprising multiple layers of silicon-based photodetectors interspersed with long-wavelength-pass optical filters. In a typical application, this heterostructure would be replicated in each pixel of an image-detecting integrated circuit of the active-pixel-sensor type (see figure).

Posted in: Briefs, TSP, Semiconductors & ICs, Imaging and visualization, Integrated circuits, Sensors and actuators, Spectroscopy

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