基于DPCA算法的星载多通道TOPSAR成像方法

摘要

方位向DPCA多通道技术能够提高星载TOPSAR模式的方位分辨率,但TOPSAR回波信号的场景多普勒频谱混叠和方位非均匀采样给多通道TOPSAR成像带来了困难.针对这个问题,提出了一种基于DPCA算法的星载多通道TOPSAR成像方法.该方法通过调整方位向发射/接收子孔径的等效相位中心位置,使等效相位中心分布基本满足均匀采样的要求,同时利用复制拼接的方法解决了TOPSAR多普勒频谱混叠问题,最后利用改进的SPECAN算法完成聚焦成像.该成像方法避免了方位向多通道非均匀采样信号的重构操作,同时复制拼接操作和改进的SPECAN算法避免了方位向数据分块操作和方位时域的扩展.点目标和分布目标的仿真结果验证了提出的成像方法.%Azimuth displaced phase center antenna ( DPCA) multi-channel technique can improve the azimuth resolution of spaceborne TOPSAR (Terrain Observation by Progressive Scans) mode, but Doppler spectrum aliasing of TOPSAR imaging scene and azimuth non-uniform sampling lead to multi-channel TOPSAR imaging hard to be implemented. As for this question, a new imaging approach for spaceborne multi-channel TOPSAR data is proposed. This approach adaptively shifts azimuth transmit/receive antenna phase center in order to yield uniformly spaced samples and resolves TOPSAR Doppler spectrum aliasing problem by the azimuth mosaicking approach. Finally, the modified SPECAN ( spectrum analysis) imaging algorithm is introduced to focus residual raw data. This imaging approach avoids azimuth multi-channel non-uniform signal reconstruction; the mosaicking approach and modified SPECAN imaging approach are introduced to avoid azimuth data block division and azimuth time domain extension. The imaging results of point and distrusted targets validate the presented imaging approach.