Deutsche Forschungsanstalt Fur Luft-und Raumfahrt E.v.

Joao R Moreira Neto

Wolfgang Keydel

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 (.DELTA.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 (.DELTA.F(t)) and a desired value (.DELTA.F.sub.soll) of the frequency offset is carried out, the frequency offset desired value (.DELTA.F.sub.soll) being determined either from the carrier forward velocity (V.sub.v) or by a low-pass filtering of the frequency offset (.DELTA.F(t)), and finally for standardization the result of the double integration is multiplied by a constant (2.pi./.DELTA.t) to obtain thereby the phase error (.phi..sub.e (t)).

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Landsberg, Germany

Joao R Moreira Neto