The Azimuth Ambiguity Suppression in Spaceborne SAR Images Using Doppler Spectrum Truncation and Amplitude Comparator

Azimuth ambiguity is widely found in spaceborne synthetic aperture radar images, which seriously affects the detection and determination of images and targets. Excellent antenna pattern and beam position designs can effectively suppress the azimuth ambiguity energy. In this case, the azimuth ambiguity energy is often concentrated on both sides of the Doppler spectrum and is further suppressed when performing spectrum weighting to suppress sidelobes operations. However, for wide dynamic range scatterers in the scene, azimuth ambiguity will still be found. Obviously, Doppler spectrum truncation can better suppress the ambiguity energy, but it also has to pay the cost of azimuth resolution degradation. In this paper, the amplitude comparator is introduced after spectrum truncation and is used to recover the resolution degradation. The proposed method can achieve similar results to the previously proposed spectral extrapolation method, while greatly improving the computational efficiency.