Title :
Onboard correction of mispointing errors in satellite altimeter returns [oceanographic measurement]
Author :
Wingham, Duncan J.
Author_Institution :
Dept. of Electron. & Electr. Eng., Univ. Coll., London, UK
fDate :
4/1/1988 12:00:00 AM
Abstract :
An investigation to determine whether useful onboard mispointing corrections to satellite altimeter measurements for errors in antenna mispointing can be made with the European Research Satellite (ERS-1) altimeter is reported. An analytic model of the nonlinear mispointing control loop is developed and the step response and signal-to-noise ratio (SNR) behavior of the loop in isolation are derived. The ERS-1 altimeter is expected to have a maximum static mispointing error of 0.2° and a maximum harmonic error of 0.1°. Taking these values as typical, it is concluded that with a loop time response of about one minute, it is not possible to correct the biased estimate of backscattering coefficient without decreasing its SNR. However, it is possible to achieve an unbiased estimate with a noise level significantly less than the uncorrected bias, but a successful implementation would require very accurately calibrated range gate samplers
Keywords :
aerospace control; aerospace instrumentation; altimeters; artificial satellites; backscatter; oceanographic techniques; remote sensing; ERS-1; European Research Satellite; altimeter; analytic model; antenna mispointing; backscattering coefficient; biased estimate; harmonic error; loop time response; mispointing corrections; mispointing errors; nonlinear mispointing control loop; oceanographic measurement; satellite altimeter returns; signal-to-noise ratio; step response; Antenna measurements; Backscatter; Error correction; Oceans; Satellites; Sea measurements; Sea surface; Signal to noise ratio; Spaceborne radar; Wind speed;
Journal_Title :
Oceanic Engineering, IEEE Journal of
