线性调频步进式合成孔径雷达系统的信号处理

Signal processing for the SAR system based on LFM subpulses with carrier frequencies increased step by step

提高距离向分辨率通常要加大发射信号带宽,导致系统采样率和A/D变换速率很高,数据量剧增,影响数据的存储和及时处理。采用调频步进方法,发射一组步进频率间隔小于信号带宽的线性调频子脉冲,对其回波信号合成处理,可以提高距离向分辨率,同时避免上述问题。在分析线性调频步进脉冲提高距离向分辨率原理的基础上,分析采用该信号对SAR距离、方位向信号处理的影响,提出线性调频步进SAR系统的信号处理流程,并用点目标信号仿真结果验证了该处理流程的正确性。

With better range resolution achieved, the bandwidth of the transmitted pulse usually has to be expanded, which consequently leads to fast A/D conversion and immense volume of raw data to be processed. An effective way to overcome such difficulty is to transmit a burst of linear frequency modulated（LFM） subpulses whose carrier frequencies are increased step by step instead of a large bandwidth LFM pulse and form the final image with fine range resolution by combining the echoes of all the subpulses. Based on the principle of improving range resolution of SAR image with burst of LFM subpulses, the effect of such subpulses on the range and azimuth signal processing is analyzed. Then the SAR image construction procedure of the system is presented. The simulation results of point target are given to support it.