超高分辨率星载SAR系统多子带信号处理技术研究

多子带信号拼接是星载合成孔径雷达（Synthetic Aperture Radar， SAR）实现超高距离分辨率的重要方式，但受限于硬件系统、大气传输等非理想因素的影响，接收各子带信号在子带内会存在幅度和相位误差，子带间也存在幅度、相位和时延不一致误差。这些误差严重影响多子带合成后的信号质量以及最终的图像质量。本文基于星载多子带SAR系统模型，首先提出了一种先单子带成像，再多子带信号拼接的成像处理策略；然后在此基础上，针对子带内/子带间幅相和时延误差提出一种基于各子带强目标点数据的误差估计与补偿方法。该方法主要包括基于质量相位梯度自聚焦（Quality Phase Gradient Autofocus， QPGA）准则的强目标点数据提取、基于PGA的子带内误差估计、子带间误差估计和误差补偿与频谱合成四个步骤。理论仿真分析数据实验验证了本方法的有效性。 

Research on Multi-subband Signal Processing Technology of Ultra-high-resolution Spaceborne SAR System

Multi-subband signal splicing is an important way to achieve the ultra-high-resolution of spaceborne synthetic aperture radar （SAR） in range. However， due to the non-ideal factors of hardware and atmosphere affections， there will be amplitude and phase errors in the received sub-band signals， and amplitude， phase and delay inconsistency errors between different sub-bands. These errors will seriously affect the quality of multi-subband splicing signal and final SAR image. Based on the model of spaceborne multi-subband SAR system， this paper first proposes an imaging processing strategy， i.e.， subband imaging and multi-subband splicing. Then， an error estimation and compensation method based on strong points data is proposed for the amplitude， phase and delay errors intra and inter subbands. This method mainly includes four steps: strong points data extraction based on quality phase gradient autofocus （QPGA）， intra subband error estimation based on PGA， inter subband error estimation and spectrum splicing. Finally， the effectiveness of this method is verified by theoretical simulation data.