Azimuth ambiguity suppression for spaceborne SAR based on PRF micro-variation

Spaceborne synthetic aperture radar (SAR) has been proved highly significant for remote sensing of the Earth. The image quality is constrained by the system design and the image processing technology, azimuth ambiguity is one of the most important factors. We know the pulse repetition frequency (PRF) determine the sampling rate of the azimuth, but the spectrum of the azimuth is non-bandlimited, it is hard to find a suitable solution with the conventional approach. A new method is proposed based on PRF micro-variation to suppress the azimuth ambiguity for spaceborne SAR, which changes the sampling mode and makes the azimuth signal no longer uniform in frequency domain. At last it can improve the image quality and make the ambiguity energy disperses randomly. In this paper, the basic theory of azimuth signal sampling is reviewed, and the reason of azimuth ambiguity is also introduced in detail. Through analysis we discover the PRF micro-variation has a scope, finally, some simulation results demonstrate this method is effective and feasible.