一种适合于斜视TOPS SAR的改进PFA成像方法

针对斜视循序扫描地形观测(TOPS)合成孔径雷达(SAR)成像模式,对广义极坐标格式算法(PFA)进行改进,提出了一种先线性走动校正(LRWC)后PFA插值的成像方法。利用LRWC显著降低了距离向与方位向的耦合,简化了距离单元徙动校正过程。走动校正后方位向采样依然是均匀的,因此方位向插值可采用Chirp-Z变换快速实现。对于波束扫描及走动校正引起的多普勒调频率的方位空变问题,采用方位非线性变标(ANCS)的方法进行统一校正,大幅提高了方位向的聚焦深度,扩大了可良好聚焦的场景范围。仿真和实测数据处理结果验证了所提方法的有效性。

An Improved PFA Imaging Method for Squinted TOPS SAR

For squinted terrain observation by progressive scans (TOPS) synthetic aperture radar (SAR) imaging mode, the generalized polar formation algorithm (PFA) is improved and an imaging algorithm, which firstly carries out the linear range walk correction (LRWC) and then applies the PFA interpolation, is proposed in this paper. The LRWC can effectively mitigate the range-azimuth coupling effect and simplify range cell migration (RCM) correction. In addition, after performing LRWC, the azimuth sampling interval is still uniform, thus the azimuth interpolation can be realized by Chirp-Z transform. For the azimuth-variation of Doppler rate induced by the antenna beam steering and LRWC, the azimuth nonlinear chirp scaling (ANCS) is implemented. Therefore, the azimuth focus depth is improved greatly and the scene size which can be well-focused is expanded. Both simulation and real data results verify the effectiveness of the proposed method.