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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,099 records · Page 61
All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

Performance of a flight qualified, thermoelectrically temperature controlled QCM sensor with power supply, thermal controller and signal processor

A thermoelectrically temperature controlled quartz crystal microbalance (QCM) system was developed for the measurement of ion thrustor generated mercury contamination on spacecraft. Meaningful flux rate measurements dictated an accurately held sensing crystal temperature despite spacecraft surface temperature variations from -35 C to +60 C over the flight temperature range. An electronic control unit was developed with magentic amplifier transformer secondary power supply, thermal control electronics, crystal temperature analog conditioning and a multiplexed 16 bit frequency encoder.

Wallace, D. A.↗
NASA NTRS1980

System for a displaying at a remote station data generated at a central station and for powering the remote station from the central station

A system for displaying at a remote station data generated at a central station and for powering the remote station from the central station is presented. A power signal is generated at the central station and time multiplexed with the data and then transmitted to the remote station. An energy storage device at the remote station is responsive to the transmitted power signal to provide energizing power for the circuits at the remote station during the time interval data is being transmitted to the remote station. Energizing power for the circuits at the remote station is provided by the power signal itself during the time this signal is transmitted. Preferably the energy storage device is a capacitor which is charged by the power signal during the time the power is transmitted and is slightly discharged during the time the data is transmitted to energize the circuits at the remote station.

Perry, J. C.↗
NASA NTRS1981

Cryogenic switched MOSFET characterization

Both p channel and n channel enhancement mode MOSFETs can be readily switched on and off at temperatures as low as 2.8 K so that switch sampled readout of a VLWIR Ge:Ga focal plane is electronically possible. Noise levels as low as 100 rms electrons per sample (independent of sample rate) can be achieved using existing p channel MOSFETs, at overall rates up to 30,000 samples/second per multiplexed channel (e.g., 32 detectors at a rate of almost 1,000 frames/second). Run of the mill devices, including very low power dissipation n channel FETs would still permit noise levels of the order of 500 electrons/sample.

Source record↗
NASA NTRS1981

Science and Applications Space Platform (SASP) End-to-End Data System Study

The capability of present technology and the Tracking and Data Relay Satellite System (TDRSS) to accommodate Science and Applications Space Platforms (SASP) payload user's requirements, maximum service to the user through optimization of the SASP Onboard Command and Data Management System, and the ability and availability of new technology to accommodate the evolution of SASP payloads were assessed. Key technology items identified to accommodate payloads on a SASP were onboard storage devices, multiplexers, and onboard data processors. The primary driver is the limited access to TDRSS for single access channels due to sharing with all the low Earth orbit spacecraft plus shuttle. Advantages of onboard data processing include long term storage of processed data until TRDSS is accessible, thus reducing the loss of data, eliminating large data processing tasks at the ground stations, and providing a more timely access to the data.

Crawford, P. R.↗
NASA NTRS1979

NASA AMES infrared detector assemblies

Silicon: Gallium infrared detector assemblies were designed, fabricated, and tested using techniques representative of those employed for hybrid arrays to determine the suitability of this candidate technology for infrared astronomical detector array applications. Both the single channel assembly and the assembly using a 32 channel CMOS multiplexer are considered. The detector material was certified to have a boron background of less than 10 to the 13th power atoms/sq cm counter doped with phosphorus. The gallium concentration is 2 x 10 to the 16th power atoms/cu cm.

Source record↗
NASA NTRS1981

Definition, analysis and development of an optical data distribution network for integrated avionics and control systems

The potential and functional requirements of fiber optic bus designs for next generation aircraft are assessed. State-of-the-art component evaluations and projections were used in the system study. Complex networks were decomposed into dedicated structures, star buses, and serial buses for detailed analysis. Comparisons of dedicated links, star buses, and serial buses with and without full duplex operation and with considerations for terminal to terminal communication requirements were obtained. This baseline was then used to consider potential extensions of busing methods to include wavelength multiplexing and optical switches. Example buses were illustrated for various areas of the aircraft as potential starting points for more detail analysis as the platform becomes definitized.

Burns, R. R.↗
NASA NTRS1981

Fiber optics for aircraft engine/inlet control

NASA programs that focus on the use of fiber optics for aircraft engine/inlet control are reviewed. Fiber optics for aircraft control is attractive because of its inherent immunity to EMI and RFI noise. Optical signals can be safely transmitted through areas that contain flammable or explosive materials. The use of optics also makes remote sensing feasible by eliminating the need for electrical wires to be connected between sensors and computers. Using low-level optical signals to control actuators is also feasible when power is generated at the actuator. Each application of fiber optics for aircraft control has different requirements for both the optical cables and the optical connectors. Sensors that measure position and speed by using slotted plates can use lossy cables and bundle connectors if data transfer is in the parallel mode. If position and speed signals are multiplexed, cable and connector requirements change. Other sensors that depend on changes in transmission through materials require dependable characteristics of both the optical cables and the optical connectors. A variety of sensor types are reviewed, including rotary position encoders, tachometers, temperature sensors, and blade tip clearance sensors for compressors and turbines. Research on a gallium arsenide photoswitch for optically switched actuators that operate at 250 C is also described.

Baumbick, R. J.↗
NASA NTRS1980

A 10 micron heterodyne receiver for ultra high resolution astronomical spectroscopy

An improved CO2 laser heterodyne spectrometer is examined. The present system uses reflective optics to eliminate refocusing at different wavelengths, and the local oscillator is a line-center-stabilized isotopic CO2 laser. A tunable diffraction grating makes possible easy and rapid selection of over 50 transitions per isotope of CO2. The IF (0 to 1.6 GHz) from the HgCdTe photomizer is analyzed by a 128-channel filter bank, consisting of 64 tunable 5-MHz filters and 64 fixed 25-MHz RF filters. These filters provide resolving powers of about 1,000,000 to 10,000,000 and velocity resolution of 50 to 250 m/sec; their output is synchronously detected, integrated, multiplexed and stored in a buffer memory for the desired integration period. Kitt Peak observations show the wide spectral coverage, wide mixer and electronics bandwidth, and high sensitivity of the system.

Buhl, D.↗
NASA NTRS1981

Video image processor on the Spacelab 2 Solar Optical Universal Polarimeter /SL2 SOUP/

The SOUP instrument is designed to obtain diffraction-limited digital images of the sun with high photometric accuracy. The Video Processor originated from the requirement to provide onboard real-time image processing, both to reduce the telemetry rate and to provide meaningful video displays of scientific data to the payload crew. This original concept has evolved into a versatile digital processing system with a multitude of other uses in the SOUP program. The central element in the Video Processor design is a 16-bit central processing unit based on 2900 family bipolar bit-slice devices. All arithmetic, logical and I/O operations are under control of microprograms, stored in programmable read-only memory and initiated by commands from the LSI-11. Several functions of the Video Processor are described, including interface to the High Rate Multiplexer downlink, cosmetic and scientific data processing, scan conversion for crew displays, focus and exposure testing, and use as ground support equipment.

Lindgren, R. W.↗
NASA NTRS1980

Thermal IR imaging system using a self-scanned HgCdTe/CCD detector array

It is likely that future high resolution earth observation imaging systems will utilize self-scanned IR detectors. In an initial step toward this goal, an IR imaging system operating in the 10 to 12 micron spectral region has been developed. This system uses a 9-element HgCdTe/CCD linear array operating in the photoconductive mode, nine pre-amplifiers and a silicon CCD multiplexer integrated into a focal plane assembly. Opto-mechanical techniques are used to scan the scene and images are produced in real time. The imaging performance of this system is described and measurements of noise, responsivity, specific detectivity, and detector sensitivity profiles are presented. The requirements for more advanced detector arrays for use in future NASA remote sensing missions are also discussed.

Husain-Abidi, A. S.↗
NASA NTRS1981

Multiwavelength monolithic integrated fiber optics terminal - An update

This paper serves as an update for the Multiwavelength Monolithic Integrated Fiber Optic Terminal (MMIFOT) being developed by MDAC-St. Louis for NASA's Johnson Space Center. The program objective is to utilize guided wave optical technology to develop a passive optical wavelength multiplexing subsystem with a single mode optical fiber serving as the transmission medium.

Spear-Zino, J. D.↗
NASA NTRS1980

Performance of the HIRS/2 instrument on TIROS-N

The High Resolution Infrared Radiation Sounder (HIRS/2) was developed and flown on the TIROS-N satellite as one means of obtaining atmospheric vertical profile information. The HIRS/2 receives visible and infrared spectrum radiation through a single telescope and selects 20 narrow radiation channels by means of a rotating filter wheel. A passive radiant cooler provides an operating temperature of 106.7 K for the HgCdTe and InSb detectors while the visible detector operates at instrument frame temperature. Low noise amplifiers and digital processing provide 13 bit data for spacecraft data multiplexing and transmission. The qualities of system performance that determine sounding capability are the dynamic range of data collection, the noise equivalent radiance of the system, the registration of the air columns sampled in each channel and the ability to upgrade the calibration of the instrument to maintain the performance standard throughout life. The basic features, operating characteristics and performance of the instrument in test are described. Early orbital information from the TIROS-N launched on October 13, 1978 is given and some observations on system quality are made.

Koenig, E. W.↗
NASA NTRS1982

Event Recorder Scans 2,048 Channels

Up to 16 input signals feed each of up to 128 input circuit cards. Single input circuit card contains optical isolators with input-diode lamping, RC filters, Schmitt-trigger input buffers, and 16-to-1 multiplexer. Input circuit cards feed logic, memory, and input/output circuits, which are standard, off-the-shelf devices. Instrument records sequence and time of events and could be useful in monitoring operation of manufacturing machinery and furnishing information useful in diagnosis of machinery malfunctions.

Slusser, K. J.↗
NASA NTRS1980

Biomedical technology transfer. Applications of NASA science and technology

Ongoing projects described address: (1) intracranial pressure monitoring; (2) versatile portable speech prosthesis; (3) cardiovascular magnetic measurements; (4) improved EMG biotelemetry for pediatrics; (5) ultrasonic kidney stone disintegration; (6) pediatric roentgen densitometry; (7) X-ray spatial frequency multiplexing; (8) mechanical impedance determination of bone strength; (9) visual-to-tactile mobility aid for the blind; (10) Purkinje image eyetracker and stabilized photocoalqulator; (11) neurological applications of NASA-SRI eyetracker; (12) ICU synthesized speech alarm; (13) NANOPHOR: microelectrophoresis instrument; (14) WRISTCOM: tactile communication system for the deaf-blind; (15) medical applications of NASA liquid-circulating garments; and (16) hip prosthesis with biotelemetry. Potential transfer projects include a person-portable versatile speech prosthesis, a critical care transport sytem, a clinical information system for cardiology, a programmable biofeedback orthosis for scoliosis a pediatric long-bone reconstruction, and spinal immobilization apparatus.

Harrison, D. C.↗
NASA NTRS1981

Infrared fiber optic focal plane dispersers

Far infrared transmissive fiber optics as a component in the design of integrated far infrared focal plane array utilization is discussed. A tightly packed bundle of fibers is placed at the focal plane, where an array of infrared detectors would normally reside, and then fanned out in two or three dimensions to individual detectors. Subsequently, the detectors are multiplexed by cryogenic electronics for relay of the data. A second possible application is frequency up-conversion (v sub 1 + v sub 2 = v sub 3), which takes advantage of the nonlinear optical index of refraction of certain infrared transmissive materials in fiber form. Again, a fiber bundle is utilized as above, but now a laser of frequency v sub 1 is mixed with the incoming radiation of frequency v sub 1 within the nonlinear fiber material. The sum, v sub 2 is then detected by near infrared or visible detectors which are more sensitive than those available at v sub 2. Due to the geometrical size limitations of detectors such as photomultipliers, the focal plane dispersal technique is advantageous for imaging up-conversion.

Goebel, J. H.↗
NASA NTRS1982

State-of-the-art cockpit design for the HH-65A helicopters

In the design of a HH-65A helicopter cockpit, advanced integrated electronics systems technology was employed to achieve several important goals for this multimission aircraft. They were: (1) integrated systems operation with consistent and simplified cockpit procedures; (2) mission-task-related cockpit displays and controls, and (3) reduced pilot instrument scan effort with excellent outside visibility. The integrated avionics system was implemented to depend heavily upon distributed but complementary processing, multiplex digital bus technology, and multifunction CRT controls and displays. This avionics system was completely flight tested and will soon enter operational service with the Coast Guard.

Castleberry, D. E.↗
NASA NTRS1982

Thematic mapper performance

The thematic mapper primarily and its difference from MSS is reviewed. The TM has 30 meter resolution and the MSS has 80 meter resolution. This provides on agriculture an ability to accurately classify 10 acre fields with the TM versus 70 acre fields with the MSS data. There are six reflected light bands in the thematic mapper. Two bands are a new spectral region out in the IR, the shortwave IR region, as opposed to MSS's four reflected light bands. Four thematic mapper reflected light bands in the visible portion of the spectrum are designated to enhance the classification capability. The TM has better signal-to-noise ratio performance and radiometric sensitivity. The scan efficiency is increased through the use of bidirectional scanning, which gives a scan efficiency of 85% versus 45% with the multispectral scanner and more detectors per band. Greater encoding resolution is obtained in the multiplexer, 8 bit resolution versus 6 bits for MSS.

Engle, J.↗
NASA NTRS1981

System data communication structures for active-control transport aircraft, volume 1

Candidate data communication techniques are identified, including dedicated links, local buses, broadcast buses, multiplex buses, and mesh networks. The design methodology for mesh networks is then discussed, including network topology and node architecture. Several concepts of power distribution are reviewed, including current limiting and mesh networks for power. The technology issues of packaging, transmission media, and lightning are addressed, and, finally, the analysis tools developed to aid in the communication design process are described. There are special tools to analyze the reliability and connectivity of networks and more general reliability analysis tools for all types of systems.

Hopkins, A. L.↗