Ground Moving Target Positioning with Doppler Ambiguity and Scene Ambiguity in SAR

摘要

A synthetic aperture radar (SAR) image is often obtained based on a part of intercepted echo from the collected raw data in the azimuth direction. It is discovered that the azimuth length of a SAR image has an effect on the target position in the image domain. For a SAR image with a large azimuth length, the azimuth shift is the distance between the original position and the final position of a moving target in the image domain, which is proportional to the target's ambiguous range velocity and is directly influenced by the Doppler ambiguity. However, for a SAR image with a limited azimuth length, the target position after azimuth shift may be beyond the boundary of the image and its final position is wrapped, which is called the scene ambiguity in this paper. When the Doppler ambiguity and the scene ambiguity both occur to one moving target, the positioning is complicated. To solve this problem, the relationship between the target's original position and final position is addressed in detail in a SAR image with any azimuth size. Then, a general positioning solution is proposed. Finally, some numerical experiments are provided to demonstrate the effectiveness of the proposed method.