基于非等间隔校正的SIFFT星机联合SAR成像算法

An Imaging Algorithm For Spaceborne-Airborne Hybrid Bistatic SAR Based on Nonuniformly-Spaced Correction of SIFFT

星机联合双基地合成孔径雷达(SA-BiSAR)系统是典型的移变双基地SAR系统,系统的移变特性导致大多数传统成像算法已不再适用.本文提出了一种适用于星机联合双基地SAR的成像算法.针对系统的移变特性,首先本文分析了变尺度FFT(SIFFT)方法,发现该方法在距离徙动校正后会出现非等间隔现象,导致方位向散焦,成像处理失败.分析表明对于星机联合SAR这种成像场景较大的情况下,SIFFT方法不再适用.对此本文进行了分析,提出了基于非等间隔校正的SIFFT算法,实现了方位向的相干积累,得到了较理想的成像效果.针对更大的成像场景,在前述算法的基础上,又提出了沿距离向变参考点的距离分块算法,完成了特大场景下的良好聚焦效果.显示了本文所提方法的通用性和有效性.

Spaceborne-airborne hybrid bistatic SAR is translational variant bistatic SAR.So the traditional algorithms are no longer suitable any more.An imaging algorithm is proposed in this paper,which suitable for Spaceborne-airborne hybrid bistatic SAR.The main idea of this method is that：decomposing the imaging space into several linearity regions,and expanding the range history in space domain in every region;find the differences of ehco sinals between reference point and other points in the regions,which can be used to reduce the computational cost.Then SIFFT is used to correcting the RM,after that the phenomenon of non-uniformly-spaced is analyzed and corrected.At last the final imaging is finished using range-dividing,and the validity of this algorithm is prooved.