SAR Azimuth Signal Reconstruction Based on Adaptive Filtering for the DPC-MAB SAR System
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摘要: 偏置相位中心方位多波束(DPC-MAB)SAR系统利用方位向多个子孔径同时接收回波，在PRF较低时根据多波束回波的相关性对其进行联合处理，实现方位向信号的重构，从而在保证高方位分辨率的同时增加测绘带宽。该文针对DPC-MAB SAR系统研究了基于波束形成理论的多普勒解模糊方法。传统非自适应的波束形成算法敏感于通道幅相误差以及各类噪声，而基于Capon算法的自适应最小方差无畸变(MVDR)最优波束形成器在多个模糊分量相关性较强时性能大大衰减，针对以往方法的局限性与不足之处，该文提出了一种改进的最小输出能量(MOE)波束形成算法，该算法首先利用多通道回波数据自适应的估计统计自相关矩阵，根据子空间投影理论对理想导向矢量进行修正，然后利用多重约束条件有效抑制相关模糊分量，解模糊性能明显提升。仿真实验和实测数据处理均验证了其有效性。Abstract: The DPC-MAB SAR system enables the reconstruction of the azimuth signal with quite low PRF by coherent process of the multichannel signals, hence relieving the contradiction of the azimuth resolution and the swath for the traditional monochannel SAR. In this paper the multichannel reconstruction algorithms based on beamforming are investigated. Considering the disadvantages of the non-adaptive beamformer and the Capon beamformer, a novel Minimum Output Energy (MOE) beamforming algorithm is proposed, which can modify the space steering vectors adaptively, and can restrain the correlative ambiguities by the multiple restrictions. The effectiveness of this method is verified by the computer-based simulations and the imaging of the real SAR data.
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