Based on single long baseline interferometer,this paper adopts the method of the secondary phase difference to steer clear of the 2π ambiguity in order to realize the fast a.

Emphasis is focused on the relationship between faults and quadratic phase coupling.

By computing the quadratic phase (QP)function of the signal,it is shown that the QP function is concentrated along the frequency rate law of the signal So the peak of the QP function yields the estimates of the frequency rate,and the initial frequency is obtained by the dechirp technique.

The data in the SAR image is corrected by subtracting the quadratic phase error, and by adding the same quadratic phase error for comparing, both results are transformed to time domain, then we get two comparing images, where the fixed background clutter have same sharpness, the moving targets have different sharpness.