基于改进方位相位编码的全极化SAR距离模糊抑制方法

Range Ambiguity Suppression Approach for Quad-pol SAR Systems Based on Modified Azimuth Phase Coding

传统全极化SAR系统交叉极化通道由于受到强同极化距离模糊信号的干扰,使得交叉极化通道的距离模糊性能急剧下降,这严重限制了全极化SAR系统的测绘带宽。该文首先介绍一种扩展的极化发射体制—混合极化模式,该模式在改善交叉极化距离模糊性能的同时恶化同极化距离模糊性能。因此,为了更好地提高全极化SAR系统的距离模糊性能,该文提出一种改进的方位相位编码方法(MAPC)。该方法通过对系统发射脉冲进行调制解调,能够将全极化SAR系统的距离模糊能量转移到方位向,然后利用方位向维纳滤波器滤除距离模糊能量。该文的实验结果表明MAPC技术能够有效地去除全极化SAR系统的距离模糊能量,并扩展系统的无模糊测绘带宽。

For conventional quadrature-polarimetric（quad-pol） Synthetic Aperture Radar（SAR） systems, as cross-polarized（cross-pol） channels are influenced by the strong co-polarized（co-pol） range ambiguous returns,the range ambiguity levels of cross-polchannels are markedly reduced, which severely restricts the unambiguous swaths. A novel transmission scheme called a hybrid-polarimetric（hybrid-pol） mode is introduced to enhance the range ambiguity levels of cross-pol channels. This scheme improves the performance of cross-pol channels with regards to range ambiguity but deteriorates that of co-pol channels. Therefore, to further enhance the range ambiguity levels of quad-pol SAR systems, the Modified Azimuth Phase Coding（MAPC） technique based on hybrid-pol SAR systems is proposed in this study. By taking advantage of the MAPC modulation/demodulation, the power of range ambiguities is transferred to the azimuth that is filtered by an optimized Wiener filter in the Doppler domain. The simulation results validate that the MAPC technique can markedly eliminate the range ambiguity of quad-pol SAR systems and extend the unambiguous swaths.