中文摘要：

当相位梯度算法挑选的散射点不是孤立散射点时，导致相位误差估计的准确性下降．对相位梯度算法中特显点的选取方法进行了改进，提出了一种基于自适应孤立特显点选择的相位梯度方法。该方法首先利用方位滑窗对各像素点进行质量评估，从而挑选出质量最好的孤立特显点用于相位误差估计，接着利用质量评估值指导多个特显点的加权综合以进一步提高相位误差估计的精度．分析和实测数据表明，对于强散射点不孤立的场景，该方法的适用性更好．

英文摘要：

If the scatter selected in phase gradient algorithm （PGA） algorithm is not isolated, the accuracy of the phase error estimation will be degraded. In this paper some modifications to the dominant scatter selection method are proposed, and then an improved PGA solution based on adaptive isolated scatter selection is presented. First, the quality of each pixel in the image is e,;aluated by a sliding window in the azimuth direction, and then the high quality scatters are selected for the phase error estimation, followed by multiple dominant scatters synthesis with the value of quality evaluated in order to improve the accuracy of the phase error estimation. Analysis and the results of real data processing show that the improved PGA algorithm outperforms the original one especially for the scene in which the bright scatters are not isolated.