نتایج جستجو برای: altimeter
تعداد نتایج: 1652 فیلتر نتایج به سال:
The excess microwave emissivity of the ocean surface due to winds at nadir incidence is derived from the TOPEX microwave radiometer and altimeter together with ocean surface data. The sensitivity of emissivity to wind speed is found to depend strongly on the air–sea temperature difference.
The design, calibration, and performance of the Mars Orbiter Laser Altimeter (MOLA) receiver are described. The MOLA measurements include the range to the surface, which is determined by the laser-pulse time of flight; the height variability within the footprint determined by the laser echo pulse width; and the apparent surface reflectivity determined by the ratio of the echo to transmitted pul...
Software GPS receiver results are presented for an overland, passive altimeter application utilizing GPS signals. The flight data were collected using a DC-3 aircraft operated by Ohio University. The flight took place over southeast Ohio, where the terrain is hilly and forested. The GPS receiver on board the aircraft contains two channels. One channel has a right-hand-circular-
-We are developing a laser radar (lidar) altimeter that uses commercial off-the-shelf fiber-optic components and traditional RF and digital signal processing techniques to achieve fine-range accuracy despite a low transmit peak power. A 1550-nm operating wavelength was selected so that available erbium-doped fiber amplifiers (EDFAs) could be used to provide optical gain. The transmitted signal,...
This paper investigates the vertical guidance performance of a multiple frequency WAAS receiver (L1, L2, and L5) in the presence of inclement weather and radio frequency interference (RFI). There are several ways to take advantage of the multiple frequencies. For example, one can calculate ionosphere delay in the airplane. This would replace the grid of ionosphere delay corrections used current...
The radar altimeters flown on Geos-3 (1975), Seasat-l (1978), and Geosat-l (1985) have amply demonstrated the benefits of high-precision measurements of ocean-surface topography, both to geodesy and to oceanography. Two new altimetry missions are planned: the joint NASA/Centre National d'Etudes Spatiales TOPEx/Poseidon mission, to be launched in 1992, and the Navy's Special Purpose Inexpensive ...
To take advantage of the unique observing capabilities of lidar technology, two NASA dedicated Earth observing laser altimeter missions are scheduled for launch in the near future: the Vegetation Canopy Lidar (VCL) and the Ice, Cloud and land Elevation Satellite (ICESat). To properly geolocate the surface returns it will be necessary to verify and calibrate pointing, ranging, timing and orbit p...
In the coastal zone (<25 km to the coast) altimetric gravity field determination degrades due to a combination of several factors, where the main reason is the degradation of the quality of the altimeter data. By starting out from the original waveform data and retracking the entire ERS1 GM mission using a highly advanced expert based system of multiple retrackers, the return time from both ope...
[1] A method for combining satellite altimetry observations with satellite measurements of the Earth’s time-varying gravity to give improved estimates of the ocean’s heat storage is presented. Over the ocean the time-variable component of the geoid can be related to the time-varying bottom pressure. The methodology of estimating the ocean’s time-varying heat storage using altimetric observation...
Elevations measured by the Mars Orbiter Laser Altimeter have yielded a high-accuracy global map of the topography of Mars. Dominant features include the low northern hemisphere, the Tharsis province, and the Hellas impact basin. The northern hemisphere depression is primarily a long-wavelength effect that has been shaped by an internal mechanism. The topography of Tharsis consists of two broad ...
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