Method of extracting phase errors caused by the atmosphere in the backscatter signal of a coherent imaging radar system carried by a carrier from radar raw data and apparatus for carrying out the method

摘要

In a method of extracting phase errors caused by the atmosphere in the backscatter signal of an on-board coherent imaging radar system from radar raw data, firstly to image areas with different backscatter ratios over a predetermined period of time consecutive azimuth spectra are continuously formed. Thereupon, a frequency offset (&Dgr;F(t)) of the backscatter ratio component is obtained by determining the location of the maximum of the correlations between two respective immediately consecutively formed azimuth spectra. Then, a double integration for the difference of the frequency offset (&Dgr;F(t)) and a desired value (. DELTA.F.sub.soll) of the frequency offset is carried out, the frequency offset desired value (&Dgr;F.sub.soll) being determined either from the carrier forward velocity (V.sub.v) or by a low-pass filtering of the frequency offset (&Dgr;F(t)), and finally for standardization the result of the double integration is multiplied by a constant (2&pgr;/. DELTA.t) to obtain thereby the phase error (&phgr;.sub. e (t)).