Method for compensating Doppler frequency of micro-wave scatterometer

Abstract

The invention relates to a method for compensating Doppler frequency of a micro-wave scatterometer, wherein the method comprises the following steps of: firstly, establishing a one-dimensional relationship table that the Doppler frequency of a wave beam centre of a micro-wave scatterometer antenna is changed along a scanning azimuthal angle of the micro-wave scatterometer antenna and a two-dimensional relationship table that the Doppler frequency of the wave beam centre of the micro-wave scatterometer antenna is changed along with the scanning azimuthal angle of the micro-wave scatterometer antenna and latitude amplitude of a satellite; then, obtaining the satellite position and the satellite speed output from the satellite in real time and calculating a correction coefficient; according to the scanning azimuthal angle of the micro-wave scatterometer antenna and the latitude amplitude of the satellite obtained in real time, finding the one-dimensional relationship table and the two-dimensional relationship table to obtain corresponding Doppler frequency of the wave beam centre of the micro-wave scatterometer antenna, correcting in real time by utilizing the correction coefficient, and obtaining the Doppler frequency of the wave beam centre of the micro-wave scatterometer antenna through a formula; and finally, compensating the Doppler frequency obtained by calculating after correcting in real time in the emission carrier frequency of the micro-wave scatterometer antenna, so as to realize compensation of the Doppler frequency of the micro-wave scatterometer.

Description

technical field [0001] The invention belongs to the technical field of microwave remote sensing, and relates to a frequency compensation method of a microwave scatterometer. Background technique [0002] The spaceborne microwave scatterometer is a typical radar system that measures the backscatter coefficient σ° of the target. It is mainly used for sea surface wind field measurement. It is one of the important remote sensing instruments that can simultaneously measure sea surface wind speed and wind direction. At present, the spaceborne microwave scatterometers working in orbit at home and abroad include SeaWinds of QuikSCAT satellite, SeaWinds of ADEOS II satellite, SeaWinds-1B of ADEOS-3 satellite, and microwave scatterometer of Haiyang-2 satellite, etc. [0003] The current Doppler frequency f of the beam center of the spaceborne microwave scatterometer d Usually calculated using the following formula: [0004] f d = ...

AI Technical Summary

Problems solved by technology

This Doppler frequency compensation method has the following deficiencies: 1. Formula (1) only considers the Doppler frequency caused by satellite motion, but does not consider the Doppler frequency caused by the earth's rotation, so the Doppler frequency obtained by its calculation is used The frequency is inaccurate; 2. The establishment of the Doppler frequency lookup table in Table 1 is only related to the scanning azimuth angle of the microwave scatterometer antenna, and has nothing to do with the orbital position of the space-borne microwave scatterometer, so the space-borne microwave scatterometer is not considered. The influence of orbital height changes at different positions on the same orbit on the Doppler frequency; 3. The satellite velocity V in formula (1) sc It is calculated under the nominal orbit and usually takes a fixed value. Therefore, when using this method for Doppler frequency compensation, it can only be used for the fixed orbit, and cannot be adaptively corrected according to the change of the orbit.

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