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At least 379 records · Page 21
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

Electronic scanning pressure measuring system and transducer package

An electronic scanning pressure system that includes a plurality of pressure transducers is examined. A means obtains an electrical signal indicative of a pressure measurement from each of the plurality of pressure transducers. A multiplexing means is connected for selectivity supplying inputs from the plurality of pressure transducers to the signal obtaining means. A data bus connects the plurality of pressure transducers to the multiplexing means. A latch circuit is connected to supply control inputs to the multiplexing means. An address bus is connected to supply an address signal of a selected one of the plurality of pressure transducers to the latch circuit. In operation, each of the pressure transducers is successively scanned by the multiplexing means in response to address signals supplied on the address bus to the latch circuit.

Coe, C. F.↗
NASA NTRS1983

The application of a color, raster scan, programmable display generator in the generation of multiple cockpit display formats

A description is provided of the application of the raster-scan, color programmable display generator (PDG) in the generation of multiple, simultaneous cockpit display formats at medium resolution, and their display on conventional R-G-B monitors and on recently developed thin film electroluminescent (TFEL) panels. The Graphics Display System of the Cockpit Systems Branch is discussed, taking into account hardware and software. Questions of system utilization are explored, giving attention to simultaneous display generation, scan standards, flat panel displays, and display enhancement software. Aspects of system performance are also examined, and an outline of future research plans is provided.

Montoya, R. J.↗
NASA NTRS1983

Incorporating geometric and radiative effects into infrared scanning computer analysis

A NASA program, the SILTS experiment (Shuttle Infrared Leeside Temperature Sensing) will utilize an infrared scanning system mounted at the tip of the vertical stabilizer to remotely measure the surface temperature of the leeside of the Space Shuttle during entry from orbit. Scans of the fuselage and one wing will be made alternately. The experiment will correlate real full scale data to ground-based information. In order to quantitatively assess the temperature profile of the surface, an algorithm is required which incorporates the Space Shuttle shape, location of specific materials on the surface, and the measurement geometry between the camera and the surface. This paper will discuss the algorithm.

Myrick, D. L.↗
NASA NTRS1984

Quaternions for Galileo scan platform control

The application of quaternions for the articulation control of the Galileo scan platform is presented in this paper. The purpose of selecting quaternions is to minimize onboard computation time and program size. Attention has been focused on performing inertial pointing while the spacecraft is in a dual spin configuration. Target quaternion and relative target quaternion are introduced and used to specify the target position of the scan platform for point-to-point absolute slews and mosaic relative slews, respectively. The pointing error of the platform is represented by an error quaternion which is converted into gimbal angular errors defining the attitude change. For path control, a moving target quaternion is generated; the corresponding tracking error quaternion and the related spacecraft motion compensation capability are also addressed. A sample slew case is used to demonstrate the implementation of these concepts.

Breckenridge, W. G.↗
NASA NTRS1984

Studies of Atmospheric Water in Storms with the Nimbus 7 Scanning Multichannel Microwave Radiometer

The new tools for the study of midlattitude cyclones by atmospheric water channels of the scanning multichannel microwave radiometer (SMMR) on Nimbus 7, were discussed. The integrated atmospheric water vapor, total cloud liquid water and rain data were obtained from the Nimbus 7 Scanning Multichannel Microwave Radiometer (SMMR). The frontal structure of several midlattitude cyclones over the North Pacific Ocean as they approached the West Coast of North America were studied. It is found that fronts are consistently located at the leading edge of the strongest gradient in integrated water vapor. The cloud liquid water content has patterns which are consistent with the structure seen in visible and infrared imagery. The rain distribution is a good indicator of frontal location. It is concluded that the onset of rain on the coast can be forecast accurately by simple advection of the SMMR observed rain areas.

Katsaros, K. B.↗
NASA NTRS1984

A scanning laser velocimeter for turbulence research

Turbulent and unsteady separated flows occur on most practical flight vehicles, but are not yet sufficiently understood for designs to provide safe margins of performance without recourse to extensive experiment and computation. In date, reliable experimental data for even basic flows is severely limited and does not yet provide a satisfactory data base with which to assess current design and calculation methods. Although the laser velocimeter (LV) has become a proven, nonintrusive instrument for the measurement of local mean velocities and turbulence properties, measurements have been of a mean, statistical nature derived from averages accumulated independently at different positions in the flow. Thus, the measurements do not give an instantaneous dynamic, picture of the flow-field structures. Accordingly, a new technique for rapid LV scans of turbulent flow fields was proposed. The potential of this new instrument for fundamental fluid mechanical measurements of turbulent flows has been demonstrated. The results clearly show that significant unsteady flow features are hidden by conventional measurements and that the scanning laser velocimeter should prove an invauable tool in future studies of the structure of turbulent flows.

Duen, F. K.↗
NASA NTRS1984

The Use of Self-scanned Silicon Photodiode Arrays for Astronomical Spectrophotometry

The use of a Reticon self scanned silicon photodiode array for precision spectrophotometry is discussed. It is shown that internal errors are + or - 0.003 mag. Observations obtained with a photodiode array are compared with observations obtained with other types of detectors with agreement, from 3500 A to 10500 A, of 1%. The photometric properties of self scanned photodiode arrays are discussed. Potential pitfalls are given.

Cochran, A. L.↗
NASA NTRS1983

Measurement of ultrasonic fields in transparent media using a scanning differential interferometer

An experimental system for the detection of three dimensional acoustic fields in optically transparent media using a dual beam differential interferometer is described. In this system, two coherent, parallel, focused laser beams are passed through the specimen and the interference fringe pattern which results when these beams are combined shifts linearly by an amount which is related to the optical pathlength difference between the two beams. It is shown that for small signals, the detector output is directly proportional to the amplitude of the acoustic field integrated along the optical beam path through the specimen. A water tank and motorized optical platform were constructed to allow these dual beams to be scanned through an ultrasonic field generated by a piezoelectric transducer at various distances from the transducer. Scan data for the near, Fresnel, and far zones of a uniform, circular transducer are presented and an algorithm for constructing the radial field profile from this integrated optical data, assuming cylindrical symmetry, is described.

Dockery, G. D.↗
NASA NTRS1984

Dependence of NOAA-AVHRR recorded radiance on scan angle, atmospheric turbidity and unresolved cloud

Experimental evidence on the scan angle and sun angle dependence of radiance recorded by the Advanced Very High Resolution Radiometer (AVHRR) devices on the NOAA-6 and NOAA-7 satellites is presented. The effects of atmospheric turbidity at various scan angles is shown, and simulations of angular anisotropy and recorded radiance are compared with the recorded digital data from the AVHRR obtained over the Great Plains area of the US. Evidence is presented on the effects of unresolved cloud on the recorded radiance and vegetative indices from uniform, vegetative targets.

Piwinski, D. J.↗
NASA NTRS1984

Method for estimating errors for radiation budget based on a scanning radiometer

The conduction of the Earth Radiation Budget Experiment (ERBE) will involve the utilization of three sets of instruments. Each set consists of a nonscanning package and a scanning radiometer. The instruments will fly on the NOAA F and G operational satellites and on a dedicated spacecraft, the Earth Radiation Budget Satellite (ERBS). The ERBS will be in a 57 deg inclination orbit and will precess around the earth to provide sampling of the diurnal cycle of regions between + or - 57 deg latitude. The primary function of the scanning radiometer is to provide measurements for the calculation of the earth-emitted and absorbed solar radiation at the top of the earth-atmosphere system, averaged over 250 x 250 km regions. The present paper is concerned with errors found in these regional averages. Attention is given to details regarding the problem, scene identification probabilities, scene identification error effects, total pixel error, and errors due to regional averaging.

Smith, G. L.↗
NASA NTRS1986

A Combined Scanning Configuration for Near-Field Antenna Measurements

Scanning configuration for near-field antenna measurements uses cylindrical and plane-polar coordinate surfaces to guide motions of electromagnetic-field probes. Near-field measurements needed especially to enable determination of far fields of large, low-sidelobe, multiplebeam antennas, for which application of far-field measurements often not suitable. New cylindrical/plane-polar scanning configuration requires less space, yet expected to give complete measurements with fewer mechanical complications.

Rahmat-Samii, Y.↗
NASA NTRS1986

Analytical techniques of pilot scanning behavior and their application

The state of the art of oculometric data analysis techniques and their applications in certain research areas such as pilot workload, information transfer provided by various display formats, crew role in automated systems, and pilot training are documented. These analytical techniques produce the following data: real-time viewing of the pilot's scanning behavior, average dwell times, dwell percentages, instrument transition paths, dwell histograms, and entropy rate measures. These types of data are discussed, and overviews of the experimental setup, data analysis techniques, and software are presented. A glossary of terms frequently used in pilot scanning behavior and a bibliography of reports on related research sponsored by NASA Langley Research Center are also presented.

Harris, R. L., Sr.↗
NASA NTRS1986

Galileo inflight friction identification for the scan platform control loop

Two types of friction identification algorithms (position-based and rate-based) are investigated in an attempt to better understand cone actuator inflight behavior in the Galileo scan platform pointing system. This investigation involves the measurement of the scan platform position (or rate) with respect to the stator following a platform slew maneuver. Inflight data collection by the spacecraft's sensors and subsequent ground-based data processing comprise the two major steps in the identification experiment. The proposed algorithms were capable of obtaining friction estimates within + or - 10 percent accuracy; hence, it is concluded that this inflight system identification technique can sufficiently tune the Galileo cone controller.

Ianculescu, G. D.↗
NASA NTRS1985

Measurements of atmospheric nitric oxide from Nimbus 7 SBUV ultraviolet spectral scan data

Results are given of SBUV (solar backscattered ultraviolet instrument) measurements from Nimbus 7, when - one day per month - it is operated in a spectral scan mode, scanning from 160 nm to 400 nm in 0.2-nm steps. By measuring the intensity of a series of nitric oxide (NO) gamma band fluorescence features in this wavelength range, it has been possible to estimate the amount of NO in the upper stratosphere and mesosphere. The background of atmospherically scattered sunlight normally masks the much weaker NO gamma band emission, but these emission features are discriminated by subtracting a synthetic spectrum calculated for a model atmosphere that includes only Rayleigh scattering and absorption by ozone and oxygen. The resulting difference plot clearly reveals features resulting from processes not included in the simple model, such as NO gamma band emission. Nitric oxide is inferred by measuring the absolute intensity of various bands relative to the adjacent background and relating this intensity to total NO above an altitude determined by the backscattering contribution function for that band. NO observations near the solstice and at various latitudes are reported.

Mcpeters, R. D.↗
NASA NTRS1987

Scanning System for Laser Velocimeter

Interference fringes remain parallel and focus-spot diameter same. Scanning system proposed for laser velocimeter (laser Doppler anemometer) to maintain constant beam-crossing angle and beam-waist diameter maintaining beam waist locations at crossing points. As target fluid scanned, interference fringes formed by crossing beams remain parallel and the focus-spot diameter same. System allows accurate velocity profiles obtained in wind tunnels and other fluid flow systems.

Gunter, William D.↗
NASA NTRS1986

A new methodology of determining directional albedo models from Nimbus 7 ERB scanning radiometer measurements

The Nimbus 7 Earth Radiation Budget (ERB) data set is reviewed to examine its strong and weak points. In view of the timing of this report relative to the processing schedule of Nimbus 7 ERB observations, emphasis is placed on the methodology of interpreting the scanning radiometer data to develop directional albedo models. These findings enhance the value of the Nimbus 7 ERB data set and can be applied to the interpretation of both the scanning and nonscanning radiometric observations.

House, Frederick B.↗
NASA NTRS1986

Multiwavelength scanning radiometer for airborne measurements of scattered radiation within clouds

A multi-wavelength scanning radiometer has been developed for measuring the angular distribution of scattered radiation deep within a cloud layer. The purpose of the instrument is to provide measurements from which the single scattering albedo of clouds can be derived as a function of wavelength. The radiometer has a 1-deg field of view and scans in the vertical plane from 5 deg before zenith to 5 deg past nadir (190 deg aperture). The thirteen channels of the cloud absorption radiometer are located between 0.5 and 2.3 microns and were selected to avoid the molecular absorption bands in the near-infrared. The first seven channels of the radiometer are simultaneously and continuously sampled, while the eighth registered channel is selected from among the six channels on a filter wheel. This paper describes the optical, mechanical and electrical design of the instrument and presents some early results obtained from measurements taken aboard the University of Washington's B-23 aircraft to illustrate the performance of the instrument.

King, Michael D.↗
NASA NTRS1986

Use of a scanning CCD to discriminate asteroid images moving in a field of stars

In the presently revealed use of a CCD in scanning mode to recover asteroids and comet nuclei, discover new asteroids in the main belt, and follow up the astrometry of selected new asteroids, the routine limiting visual magnitude is 19.6. Semiautomatic software for detection of moving objects is in use, allowing angular speeds as low as 11.0 arcsec/hr to be distinguished from the effects of the earth's atmosphere on the field of view. A typical set of three 29-min scans near the opposition point along the ecliptic typically nets at least five new main belt asteroids down to magnitude 19.6. In 18 monthly observing runs, 59 new asteroids have been obtained and 22 comets have been located.

Mcmillan, R. S.↗