基于方位FNCS的斜视TOPS SAR成像方法

针对斜视循序扫描地形观测（terrain observation by progressive scans, TOPS）合成孔径雷达（synthetic aperture radar, SAR）模式，提出了一种新的全孔径成像处理方法。首先对距离走动校正后的数据进行方位预处理得到无模糊的二维频谱，在此基础上采用修正的线频调变标算法完成距离脉压及距离徙动校正；然后在距离多普勒域进行频域非线性变标（frequency nonlinear chirp scaling, FNCS）以校正调频率的空变性，并结合谱分析（spectral analysis, SPECAN）技术将信号聚焦在方位频率域，最后校正几何形变。仿真和实测数据处理结果验证了算法的有效性。

Squint TOPS SAR imaging method based on azimuth FNCS

For squint terrain observation by progressive scans (TOPS) synthetic aperture radar (SAR) mode, this paper proposes a new full-aperture imaging algorithm. Firstly, the two dimensional (2-D) spectrum without aliasing is obtained by the azimuth pre-processing after range walk correction. Then the modified chirp scaling algorithm is used to complete range compression and range cell migration correction (RCMC). After that, by using a frequency nonlinear chirp scaling (FNCS) method in the range Doppler domain, the variation of the FM rates is corrected, and the signal is focused in the Doppler domain by SPECAN technique. Finally, geometric distortion correction is carried out. Both simulation and real data processing results demonstrate the effectiveness of the proposed method.