基于特征分解的方位向多通道SAR相位失配校正方法

Channel Phase Mismatch Calibration for Multichannel in Azimuth SAR Imaging Based on Eigen-structure Method

作为实现高分辨率宽幅成像的重要技术手段之一,方位多通道合成孔径雷达(Synthetic Aperture Radar,SAR)近年来得到了广泛的研究与发展。在进行多通道数据重建之前,通道之间的传输特性必须校正一致,以避免图像中出现严重的虚假目标。在多通道SAR数据处理中,精确的基带多普勒中心估计对系统的通道失配校正和高分辨率成像具有非常重要的意义。但是单一通道数据的多普勒频谱混叠制约了传统基带多普勒中心估计算法在方位多通道SAR系统中的应用。基于特征分解处理,该文提出一种新的基带多普勒中心估计方法。该方法在推导过程中考虑了波束指向存在斜视的影响,能够实现方位多通道SAR系统基带多普勒中心和通道间相位误差的鲁棒估计。仿真实验和C波段方位向四通道机载SAR实验数据处理分析验证了算法的有效性。

As one of the most important means to achieve a High-Resolution and Wide-Swath（HRWS）imaging of the earth,multichannel in azimuth Synthetic Aperture Radar（SAR）have attracted considerable attention in recent years.However,prior to the unambiguous reconstruction of the multichannel SAR signal,each channel needs to be well calibrated,otherwise the performance of the reconstruction processor may degrade or even lose its effectiveness.Accurate baseband Doppler centroid estimation are critical for channel mismatch calibration and high-resolution imaging in the multichannel SAR systems.However,in the multichannel HRWS SAR system,the signal acquired by each channel is under-sampled that renders the traditional Doppler centroid estimation methods obsolete.In this paper,an eigen-structure method has been used to achieve a robust estimation of the baseband Doppler centroid and the phase mismatch in the multichannel SAR system.Processing with simulated and experimental C-band,four-channel airborne SAR data validates the effectiveness of this method.