中文摘要：

平地相位是在合成孔径雷达干涉处理（InSAR）过程中，平坦地表所产生的线性变化相位，它的存在不仅增加了相位解缠的难度，而且它去除的干净程度将直接影响InSAR处理结果的精度，因此。去平地相位是InSAR处理中关键技术之一。在卫星精轨数据已知的情况下，平地相位可以精确地计算得到，但是对于ALOS／PALSAR数据产品而言，其提供的卫星状态采样点时间间隔达到60S，平地相位计算成为利用PALSAR开展InSAR研究的难点，也构成了PALSAR InSAR推广应用的瓶颈。通过分析常用轨道参数估计方法的优缺点，分别利用埃尔米特等距插值法、三次样条插值法和最小二乘多项式拟合法对常州地区的ALOS／PALSAR数据进行了卫星轨道估计对比实验，并应用于平地相位消除。实验结果表明，埃尔米特等距插值法可以有效估计卫星状态矢量采样稀疏的加密精轨数据，实现平地相位地精确计算与去除。

英文摘要：

Flat-phase is the linear phase which is caused by flat ground in the interferometric processing of SAR. It increases the difficulties of phase unwrapping, and its removal accuracy also affects the processing results of InSAR. So flat-phase removal is one of the critical steps of InSAR processing. Generally, flat-phase can be calculated accurately if precise orbit state vectors are available. However, the orbit sampling interval of ALOS satellite is 60-second. Generating the flat phase exactly is one of the difficulties in interferometric processing for ALOS/PAI.SAR data, which also limits the InSAR application of PALSAR data. In this paper, by analyzing different methods for estimating orbit state vectors, we utilize the Hermite interpolation on equidistant nodes and apply the estimated results to remove flat-phase. ALOS/PALSAR data of Changzhou City, Jiangsu Province were used to evaluate the proposed method. Finally, we compared Hermite interpolation on equidistant nodes with cubic spline interpolation and least squares polynomial regression.