条带SAR重叠子孔径算法成像限制的研究

Research on Imaging Limit of Overlapped Subaperture Algorithm for Strip SAR

直接面向距离向脉冲压缩的条带重叠子孔径算法(Overlapped Subaperture Algorithm,OSA)成像算法无需在接收端进行去斜处理,在距离向采用脉冲压缩获得高分辨率,在方位向通过子孔径划分、二级FFT获得高分辨率。该算法在方位向第一级处理时需在子孔径内忽略波前弯曲效应、完成低分辨率成像,距离向脉冲压缩之前需要将距离方位的耦合误差限定在一定范围内并进行补偿,因此引入了算法的使用前提条件。对适用于距离向脉冲压缩条带OSA算法的成像限制进行了研究,简单介绍了成像算法的回波模型与算法流程并引入了算法使用限制条件,对使用限制条件进行了详细的数学推导,明确了算法适用范围,总结了影响方位向与距离向成像尺寸、子孔径划分的主要因素。通过条带SAR重叠子孔径算法成像限制的研究对雷达系统参数选取、技术指标制定和成像处理参数选取等有指导意义。

The overlapped subaperture algorithm （OSA） for range pulse compression strip SAR can obtain high-resolution SAR image by pulse compression in range direction and two-stage FFT in azimuth direction without dechirping at the receiving end.The wavefront bending effect can be ignored when the algorithm is processing in the azimuth subaperture and completes low-resolution imaging. The range-azimuth coupling error must be limited within a certain range and be compensated before range-direction pulse compression. Therefore the premise condition of using the algorithm is introduced.In this paper,the imaging limit of OSA algorithm for pulse compres- sion strip is studied.Firstly,the echo model of imaging algorithm, the algorithm flow and its limiting condition are introduced.Then, a detailed mathematical derivation is done on the limiting condition.At last, the algorithm＇s range of application is defined and the main factors affecting imaging size in azimuth and range direction and subaperture division are concluded.The research on imaging limit of overlapped subaperture algorithm for strip SAR has a guiding significance on parameter selection of radar system,technical specification formulation, parameter selection of imaging process and so on.