Abstract
For bistatic forward-looking synthetic aperture radar (BFSAR), images are often blurred by uncompensated radar motion errors. To get refocused images, autofocus is a useful postprocessing technique. However, a severe drawback of the autofocus algorithms is that they are only capable of removing one-dimensional azimuth phase errors. In BFSAR, motion errors and approximations of imaging algorithms introduce residual range cell migration (RCM) on BFSAR data as well. When residual RCM is within a range resolution cell, it can be neglected. However, the residual migration, which exceeds a range cell, is increasingly encountered as resolution becomes finer and finer. A novel residual RCM correction method is proposed in this paper. By fitting the low-frequency phase difference of adjacent azimuth cells, residual RCM of each azimuth cell can be corrected precisely and effectively. Simulations and real data experiments are carried out to validate the effectiveness of the proposed method.
Highlights
Forward-looking imaging is highly desirable in some applications, such as airplane navigation and landing
In the presumption that residual range cell migration (RCM) is within a range resolution cell, residual RCM can be neglected [2, 3], and motion errors can be compensated by autofocus methods completely
4 Experimental results both of the point target simulation and the real data experiment are performed to evaluate the performance of the proposed residual RCM correction algorithm for bistatic forward-looking synthetic aperture radar (BFSAR)
Summary
Forward-looking imaging is highly desirable in some applications, such as airplane navigation and landing. Due to the ability to obtain high-resolution image of the forward-looking terrain, bistatic synthetic aperture radar (SAR) is drawing more and more attention in recent years. The moving platforms introduce relative motion between radars and observed scene, which induces range cell migration (RCM) to bistatic forward-looking SAR data. RCM cannot be corrected completely in practical application. The residual RCM is introduced by motion errors [1]. In the presumption that residual RCM is within a range resolution cell, residual RCM can be neglected [2, 3], and motion errors can be compensated by autofocus methods completely. Residual RCM is relatively small and can be neglected in monostatic SAR, while the unique characteristics of BFSAR makes the residual RCM
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