一种用于TOPS SAR-GMTI的空时自适应处理方法

Spectrum compression space-time adaptive processing method for TOPS SAR-GMTI

针对在循序渐近对地扫描合成孔径雷达(TOPS SAR)模式下静止背景杂波的多普勒带宽很大,在有限的脉冲重复频率(PRF)条件下,会导致背景杂波出现严重的多普勒模糊问题,提出了一种基于谱压缩的空时自适应处理方法进行杂波抑制.经过谱压缩操作后,杂波的多普勒带宽减小到与其瞬时带宽相同,再利用空时自适应处理(STAP)方法进行杂波抑制,使得杂波抑制性能得到明显改善.同时,由于动目标径向速度的存在,会导致其多普勒频谱产生偏移,而直接采用匹配滤波方法对动目标进行聚焦,会造成虚假目标的出现.为了避免出现这一现象,可利用Deramp处理方法对动目标进行聚焦处理,能有效避免虚假目标的产生.同时利用TOPS SAR模式获得连续的重叠率很高的全孔径TOPS SAR图像,可以实现动目标的轨迹跟踪处理.最后,通过仿真实验验证了所提方法的有效性.

Moving targets detection and imaging for multichannel terrain observation by progressive scans （TOPS） synthetic aperture radar ground moving targets indication （SAR-GMTI） has important application prospects. However, the azimuth bandwidth of the background clutter is much larger than the instantaneous signal bandwidth. Therefore, the background clutter will be highly aliased if the pulse repetition frequency （PRF） is limited. Direct application of space-time adaptive processing （STAP） techniques will significantly compromise the clutter suppression performance. Hence, we propose a space- time adaptive processing method based on spectrum compression. The spectrum compression process can reduce the azimuth bandwidth of the background clutter to the instantaneous signal bandwidth. Space-time adaptive processing is then performed to effectively suppress the clutter, and the clutter suppression performance is greatly improved. Furthermore, Deramp processing is used to focus the moving target in order to avoid the target ambiguities arising from the Doppler shift. Meanwhile, we can perform the moving targets tracking by utilizing the highly overlapping full-aperture images which are obtained by the TOPS SAR mode. Simulation results validate the effectiveness of the proposed algorithm.