非线性Chirp Scaling在机载SAR成像中的应用

Application of nonlinear Chirp Scaling in airborne SAR imaging

非线性Chirp Scaling算法可以处理大耦合SAR回波,实现精确聚焦。与CS算法类似,NCS操作引起了距离向频谱扩展、调频率微调及距离压缩曲线偏移,只有在一定的成像测绘带宽度内这些影响才能被忽略。针对这一问题展开论述,通过仿真比较了NCS算法应用于典型机载L波段和P波段SAR成像时对距离谱的影响,从而确定可以理想聚焦的测绘带宽度。该结论对分段成像有一定的指导意义,应用于某机载P波段UWBSAR实测回波成像。

Nonlinear Chirp Scaling （NCS） algorithm is able to deal with high coupling SAR echoes and achieve fine focusing images. Like the CS algorithm, NCS operation will bring also some affixed effects, such as expanded range spectrum, adjusted frequency modulated rate and shifted range-compressed curves. Only to keep a certain imaging range, can these effects be neglected. By airborne L band and P band SAR image formation are compared, the detailed analysis of the NCS operation effects to range frequency are shown, while an ideal focusing swath range is proposed as conclusion. Using this conclusion as a guide, the wide swath UWB （ultra-wide band） SAR data are obtained.