基于空时等效采样复用的星载SAR宽域运动目标检测与成像

Moving target detection and imaging for Spaceborne SAR in wide-swath based on repeated usage of space-time equivalent samplings

高分辨宽测绘带静态场景成像与运动目标检测与成像是星载合成孔径雷达(SAR)两个重要功能需求,也是新体制SAR的前沿和重点。现有的基于阵列接收多相位中心技术可解决方位分辨率与测绘带宽的矛盾,但其空时等效单通道数据难以实现运动目标的有效检测。现有的多通道SAR能改善杂波抑制和运动目标检测性能,但其对静态场景成像时仍存在方位分辨率与测绘带宽的矛盾。本文提出一种基于空时等效采样复用的信号处理新方法,同时改善了星载SAR在高分辨率宽测绘带静态场景成像与运动目标检测与成像两方面的性能。进而,本文深入研究目标径向速度在等效回波信号中引入的周期调制产生的目标方位像的"假峰"效应,并提出了有效的抑制"假峰"的补偿方法。最后,数值仿真试验验证了新方法的有效性。

The modern spaceborne synthetic aperture radar（SAR） has two strong application demands on the high-resolution and wide-swath imaging as well as the moving target detection and imaging, which also attracts more and more attentions in the new-generation SAR. The exsiting multiple phase centers technique via array receiver may well solve the imaging tradeoff between azimuth high-resolution and wide-swath, but it＇s hard to detect moving target effectively by using the equivalent single-channel receiving data. Meanwhile, the exsiting multi-channel SAR can remarkably improve clutter suppression performance, but it cannot overcome the above tradeoff. In this paper, a novel signal processing method is proposed for spaceborne SAR based on repeated usage of the space-time equivalent samplings, which can improve the performance of high-resolution and wide-swath imaging and moving target processing, simultaneously. Furthermore, this paper gives a deep insight of the azimuth ＂spurious peaks＂ effect, due to the periodically modulated signal caused by the radial velocity of moving target. Also, the effective compensation method is proposed to suppress the unwanted ＂spurious peaks＂. Finally, the numerical experiments are also provided to demonstrate the effectiveness of the proposed method.