基于方位Deramp处理的宽覆盖DBS全孔径成像方法

A Full-aperture Imaging Approach for Wide Swath DBS Based on Azimuth Deramp Processing

为了获得大幅宽多普勒波束锐化(DBS)图像,现有的DBS成像算法往往需要进行复杂图像拼接。此外,现有成像方法为了保证DBS图像的锐化比恒定,除了要实时调整波束扫描速度外,还需要实时调整脉冲重复频率或积累脉冲个数,使得系统复杂度显著增加。文中在深入研究DBS成像机理的基础上,提出了一种基于方位Deramp处理的宽覆盖DBS全孔径成像方法。该方法利用方位Deramp消除了全场景回波的多普勒频谱混叠,无需进行图像拼接,通过一次全孔径FFT就能获得宽覆盖DBS图像。同时,只需实时调整波束指向,该方法就能实现恒定锐化比成像。实测数据处理结果证明文中方法的有效性。

To obtain wide swath Doppler beam sharpening （DBS） image, the existing DBS imaging algorithms usually require compli- cated image stitching. Furthermore, to keep the constant sharpening ratio of DBS image, it is also necessary to real-time adjusting the pulse repetition frequency or the numbers of integrated pulses in current imaging method besides real-time adjusting the rate of beam scanning, which evidently increases the system complexity. Based on the in-depth study on DBS imaging principle, a full-aperture imaging approach for wide swath DBS using azimuth deramp processing is presented. The aliasing Doppler spectrum of the whole scene is obtained by the azimuth deramp processing, and then wide swath DBS image can be acquired by one full-apeture FFr without image stitching. Moreover, the constant sharpening ratio image can be easily achieved by the proposed approach with real-time adjus- ting of beam direction. The validity of the presented approach is confirmed by the processing results of real data.