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Results for “RADAR INSTRUMENTATION”

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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS2003

Conceptual design of a geostationary radar for hurricane studies

A novel 35-GHz Doppler radar instrument concept and the associated critical technologies are being developed for detailed monitoring of hurricanes and severe storms from a geostationary orbit. This instrument is designed to make quantitative rainfall rate profiling measurements at 13-km horizontal resolution and 300-m vertical resolution, and the radial Doppler velocity at 0.3 m/s precision, of the 3-D hurricane structure once per hour throughout its life cycle.

precipitation↗
NASA NTRS1998

On the Scan Performance of Phased Array Fed Cylindrical Reflector with SuperQuadric Projected Aperture: PO/FFT Analysis

The need for enhanced observational capabilities in a spaceborne microwave radar instrument to measure rainfall rates, vertical velocities with precipitation, and latent-heating profiles accurately and at sufficiently good resolution and spatial coverage throughout the tropics and mid-latitudes requires a large antenna with high-performance beam-scanning capabilities to avoid contamination by the surface clutter known as range ambiguity.

Scan↗
NASA NTRS1984

Venus: Global radar properties in a geological context

The radar altimetry, roughness (RMS slopes), and reflectivity data acquired for Venus represent the only global radar information available for any of the planets. In addition, the Pioneer Venus radar instrument was able to sound the surface at normal incidence so that it was possible to accurately measure the small-scale surface slopes and reflectivity (dielectric and porosity properties) at the same time as the surface elevation. Analyses of the topography of Venus demonstrate that it differs in its distribution from the Moon, Mars, or the Earth. While the range of topography extends from -2.5 km below the reference level to 11.5 km above, most of Venus falls within 1 km of the mean elevation, this is in sharp contrast to the Earth. The narrow, unimodal nature of the distribution of topography on Venus evidently exerts control on the other radar-derived properties of the surface. When clustering analysis techniques are applied to the Venus radar data sets, the result demonstrates that topographic zones serve as the best criteria for distinguishing regions on Venus which have related radar properties. The individual radar data sets are investigated separately and in conjunction with topography.

Garvin, J. B.↗
NASA NTRS2011

A Study of Radio Frequency Interference in the Space-to- Earth Exploration Allocation at L-Band

We report on ongoing studies of the anthropogenic radio frequency interference (RFI) in the Lband allocation for space-to-Earth exploration.1,2 The studies are being conducted for the radar instrument on the proposed Soil Moisture Active/Passive (SMAP) mission. A review of the allocated emitters is presented, followed by analysis based on space-borne and airborne data collected from the PALSAR sensor and the UAVSAR sensor. We use these data to model the pulsed RFI environment for SMAP and to demonstrate that the baseline plans for RFI mitigation are technically sound.

radiofrequency interference↗
NASA NTRS2012

Digital Calibration of TR Modules for Real-Tme Digital Beamforming SweepSAR Architectures

Real-time digital beamforming, combined with lightweight, large aperture reflectors, enable a new architecture, which is the baseline for the proposed DESDynI [Deformation, Ecosystem Structure, and Dynamics of Ice] SAR [Synthetic Aperture Radar] Instrument (or DSI). This new instrument concept requires new methods for calibrating multiple simultaneous channels. The calibration of current state-of-the-art Electronically Steered Arrays typically involves pre-flight TR (Transmit/Receive) module characterization over temperature, and in-flight correction based on measured temperatures. This method ignores the effects of element aging and any drifts unrelated to temperature. We are developing new digital calibration of digital beamforming arrays, which helps to reduce development time, risk and cost. Precision calibrated TR modules enable real-time beamforming architectures by accurately tracking modules' characteristics through closed-loop digital calibration, which tracks systematic changes regardless of temperature. The benefit of this effort is that it would enable a new, lightweight radar architecture, with on-board digital beamforming. This provides significantly larger swath coverage than conventional SAR architectures

Hoffman, James Patrick↗
NASA NTRS2004

Mitigation of tropospheric InSAR phase artifacts through differential multisquint processing

We propose a technique for mitigating tropospheric phase errors in repeat-pass interferometric synthetic aperture radar (InSAR). The mitigation technique is based upon the acquisition of multisquint InSAR data. On each satellite pass over a target area, the radar instrument will acquire images from multiple squint (azimuth) angles, from which multiple interferograms can be formed. The diversity of viewing angles associated with the multisquint acquisition can be used to solve for two components of the 3-D surface displacement vector as well as for the differential tropospheric phase. We describe a model for the performance of the multisquint technique, and we present an assessment of the performance expected.

troposphere↗
NASA NTRS2006

A Conceptual Titan Orbiter Mission Using Advanced Radioisotope Power Systems

This study details a conceptual follow-on Titan orbiter mission that would provide full global topographic coverage. surface imaging, and meteorological characterization of the atmosphere over a nominal 5-year science mission duration. The baseline power requirement is approx.1 kWe at EOM and is driven by a high power radar instrument that would provide 3-dimensional measurements of atmospheric clouds, precipitation, and surface topography. While this power level is moderately higher than that of the Cassini spacecraft. higher efficiency advanced RPSs could potentially reduce the plutonium usage to less than 1/3rd of that used on the Cassini spacecraft. The Titan Orbiter mission is assumed to launch in 2015. It would utilize advanced RPSs to provide all on-board power.

radioisotope power systems (RPS)↗
NASA NTRS1977

Determination of ocean wave heights from synthetic aperture radar imagery

A calculation is presented for the cross-correlation of the radar images obtained by processing the same signal data over different portions of the chirp spectrum bandwidth as a function of the center frequency spacings for these portions. This is shown to be proportional to the square of the product of the characteristic function for ocean wave heights and the pupil function describing the chirp spectrum bandwidth used in the processing. Measurements of this function for ocean wave imagery over the coast of Alaska, the North Atlantic, and Monterey Bay, California, and correlation with the significant wave heights reported from ground truth data indicate that the synthetic aperture radar instrument can be used for providing wave height information in addition to the ocean wave imagery.

Jain, A.↗
NASA NTRS1982

Land remote sensing activities in the US

The LANDSAT D system, shuttle imaging radar instruments, the thermal infrared multispectral scanner system, the shuttle multispectral infrared radiometer, and the multispectral linear array program are described. These programs will develop advanced optical and microwave sensor technologies to support a broad spectrum of aircraft, shuttle and free flier missions for research in agriculture, geology, hydrology and geography. A broad based fundamental research effort coupled with the development of improved data acquisition and information extraction techniques is planned to improve fundamental understanding of the remote sensing process and fully exploit its capabilities.

Keller, S. W.↗
NASA NTRS1982

The NASA Radar Remote Sensing Program

The NASA radar remote sensing program is structured to conduct scientific research for earth and planetary exploration using the microwave spectrum. The program began in 1966 and has since developed a complement of radar sensors for satellite, aircraft and ground-based platforms which have been used in both land and oceanic research. Basic measurements of radar scattering coefficient signatures are carried out with airborne and ground-based scatterometers. SAR imagery is being used for geological, hydrological, geographical, and agricultural microwave remote sensing research. For oceanic investigations, altimeters are used for ocean topography experiments and scatterometers for ocean wind and current research. Future satellite radar instruments being proposed include SIR-B, SAMEX, FIREX, TOPEX and a Scatterometer Experiment.

Carver, K. R.↗
NASA NTRS1983

Airborne remote sensing measurements with a pulsed CO2 DIAL system

The present investigation is concerned with an optical radar instrument which has been developed for airborne remote sensing of atmospheric trace species at infrared wavelengths. The instrument makes use of compact, pulsed carbon dioxide lasers. It was designed for conducting differential absorption lidar (DIAL) measurements. The backscatter of laser pulse energy from the ocean and terrain surface is utilized to determine trace species column content. The instrument, which is carried by the NASA P3 aircraft, is used in a flight test program started in July 1981. The results obtained with the instrument in this program are discussed, taking into account ocean surface backscatter statistics, the ratio of ocean to terrain backscatter, the dual-wavelength correlation coefficient, the dual-wavelength cross-covariance, and the dependence of un-correlated noise variance on the mean backscatter signal.

Bufton, J. L.↗
NASA NTRS1986

The SIR-C ground data system: Digital processor, data products, information flow

The SIR-C (Shuttle Imaging Radar) instrument will collect both C-Band and L-Band data with each frequency band consisting of direct (HH or VV) and cross-polarized (HV or VH) data. Considering all possible combinations as many as eight different data channels will be available for any given target area. This data will be digitized and formatted on-board for direct downlink via the Tracking and Data Relay Satellite System (TDRSS), or it will be buffered through on-board high density digital recorders for storage or transmission when TDRSS is available. The data is received by the TDRSS ground station at White Sands and is nominally relayed via DOMSAT to the high data rate recording facility at GSFC. The tapes are then shipped to JPL for processing into imagery and eventual distribution to the SIR-C investigators.

Curlander, John C.↗
NASA NTRS1994

NLC-91: An experimental study of the polar summer mesosphere

In the summer of 1991, a major scientific campaign (NLC-91) involving 31 rocket flights was conducted from ESRANGE, Kiruna, Sweden and from Heiss Island, Russia to investigate the chemical, dynamical, and electrodynamical properties of the polar summer mesosphere. The rocket flights were also coordinated with two coherent radar facilities, EISCAT (European Incoherent Scatter Scientific Association) and CUPRI (Cornell University Portable Radar Instrument), as well as other ground facilities, to provide continual monitoring of the mesosphere by remote sensing techniques. The primary objectives of the campaign were to study noctilucent clouds (NLC's) and polar mesospheric summer echoes (PMSE's), including their possible relationship to local aerosols and/or small scale turbulence. The program involved scientific participation from eight countries, and promises to produce many results during the next few years. This overview considers the scientific campaign and briefly discusses preliminary results. These results are provided in more detail in papers following this overview.

Goldberg, R. A.↗
NASA NTRS1994

Directional wind wave development

Using aircraft radar instruments designed for sea surface wave measurements, we have obtained fetch-limited directional wind wave spectra under steady off-shore wind conditions. The results from these observations in different areas at different times show that, up to a fetch of 150 km, the dominant waves propagate at an angle to the wind. The angle is near to that suggested by the Phillips resonance wind wave generation condition, but with one important difference: The waves are not always symmetric to the left and right of the wind. Most of the cases show the eventual dominance of one side lobe. The asymmetry of the wave direction relative to the wind suggests that the surface wind stress vector may not always be parallel to the mean wind direction.

Long, Steven R.↗
NASA NTRS2000

STS-99 Crew Activities Report/Flight Day 1 Highlights

Live footage shows the crew, Commander Kevin R. Kregel, Pilot Dominic L. Pudwill Gorie, and Mission Specialists Janet L. Kavandi, Janice E. Voss, Mamoru Mohri and Gerhard P.J. Thiele, seated in the dining room with the traditional cake. The crew is seen performing various pre-launch activities including suit-up, walk out to the Astro-van, and strap-in into the vehicle. Also seen are the retractions of the orbiter access arm and the gaseous oxygen mint hood, main engine start, booster ignition, liftoff, and separation of the solid rocket boosters. The Red Team (first of the dual shift crew) includes Kregel, Kavandi, and Thiele, who are shown conducting jet thruster firings, activating radar instruments, and deploying the boom (mass).

Source record↗