星载滑动聚束SAR成像模型误差校正方法研究

摘要

合成孔径雷达(SAR)滑动聚束模式是介于传统条带模式和聚束模式之间的成像模式.该文针对高分辨率宽覆盖星载滑动聚束SAR合成孔径时间和一次成像时间均较长的特点,分析了由此引发的传统等效距离模型精度不足以及模型参数沿方位向时变性显著的问题.借鉴机载SAR运动补偿理论,提出了利用星载滑动聚束SAR“非匀速直线运动”引起的到虚拟转动点距离误差来校正方位时变模型参数的方法,并相应给了判断是否需要校正的依据；针对校正后数据中孔径内残留的等效距离模型三次误差,提出了在多普勒域内的统一补偿的方法；结合上述模型误差校正方法,重新定义了滑动聚束DCS算法中的CS因子,给出了处理流程.最后,用计算机仿真实验验证了模型校正方法的有效性.%Sliding spotlight SAR, which is between strip-map SAR and spotlight SAR, is a unique imaging mode. Concerning on the long illuminating time and long accumulating time of high-resolution and wide-coverage-area space-borne sliding spotlight SAR, the precision and the azimuth-time-variant characteristic of the traditional imaging model are analyzed in this paper. Based on the theory of motion compensation for airborne SAR, a method to correct the azimuth-time-variant error, which makes use of range error caused by non-linear movement of space-borne SAR relative to the virtual rotating point, is presented. In addition, a method to compensate the remnant cubic error of the imaging model in Doppler domain is also given here. Finally, a new DCS algorithm with imaging model error mending is introduced, whose validity is verified with computer simulation.