基于频谱偏移方法改进SAR影像距离分辨率

Improving Range Resolution of SAR Image by Spectral Shift Method

通过对接收数据进行处理,可以将两次或多次测量的影像频谱叠加,从而获得更宽的距离向信号带宽,由此提高斜距分辨率。从频谱偏移原理出发,利用两次测量数据的干涉结果,将两次测量数据的频谱进行偏移对准,从而合成为一个具有更大带宽的影像数据,进而提高距离向分辨率。实验证明,通过对两次测量数据进行频谱合成,得到了更高斜距分辨率的影像。一般情况下,基线越大,合成后影像带宽越大,分辨率改善效果越好。理论上,在极限基线下,最大可以获得相当于原始影像两倍带宽的合成影像。多幅SAR影像合成在改进距离向分辨率的同时,还能在一定程度上消除非固定散射目标和旁瓣,对影像质量有一定的改善。

The spectral shift between SAR images could induced by the difference of incident angles of acquired images in the same coverage.In order to improve the range resolution of SAR image,we can expand the range bandwidth of SAR images by combining the spectral of two images or more.In this paper,the spectral of two images is aligned based on the spectral shift theory,and an image of wider bandwidth is acquired.Then the image with improved range resolution can be obtained.The bandwidth of combined image is theoretically proportional to the baseline of two images.Considering the critical baseline,we could acquire the combined bandwidth twice to the original image.The images combined with more than two images can not only improve the range resolution of SAR images,but also remove the non-stationary target and side-lobe effect.