干涉合成孔径雷达成像技术研究

用SIR-C/X-SAR的X波段的原始数据,实现了真实数据下星载双航过InSAR的数字高度
地图。首先给出了一种新的解释InSAR三维成像原理的数学描述。该描述对成像关系做了合理近
似,与以前的一些描述相比具有如下优点:①把相位差与地表高度在距离线上直接联系在一起,清
晰地反映出它们之间的关系;②指明了基线对高度测量的有效贡献在于其在斜距垂直方向的投影
这一重要概念;③可用于对测高精度与部分成像参数之间的关系做理论分析;④可用于求取相位差
值到地表高度值之间的转换系数;⑤基本反映了成像处理的实际过程;⑥可解释为何工程上可将相
位差与高度之间近似看成线性关系。然后,给出了一个完整的实现数字高度地图的数据处理过程,
并将整个过程分成9个环节,逐一对各环节的目的和作用做了扼要说明。最后,给出了包括单视
SAR成像、干涉相位条纹、水平相差修正和干涉条纹的降噪滤波在内的处理过程中关键步骤的结
果,和最终的三维地貌成像结果。

Study on Interferometric SAR 3-Dimensional Remote Sensing

Using the X band raw data from SIR C/X SAR, we have succeeded in the formation of an actual spaceborne two pass InSAR Digital Elevation Model. In this article, a new mathematical expression has been proposed to illustrate the principle of this 3D InSAR imaging technique. In the obtaining of this new expression, reasonable approximation was used. Compared with other principle illustrations, it has the following advantages:(1) With only one expression, the relation between the terrain height to be sensed and the phase difference of interferogram in a range line is clearly exposed. (2) An important concept is revealed that the valid component of baseline for height measuring is its projection in the direction vertical to the slant range. (3) It enabled the theoretical analysis of height measuring accuracy affected by some geographic parameters. (4) It can be used for the conversion of the phase difference to terrain height. (5) It suggests the course of signal processing of InSAR. (6) It shows why the relation between phase difference and terrain height is usually considered to be linear in practice. Then, a whole procedure of signal processing of InSAR is given. It is divided into nine steps, and functions of each step have been briefly explained. Last, results of some key steps such as single look complex image of SAR, phase fringe image of interferogram, flat earth modified phase fringe, noise reduced phase fringe, and the final 3D topography are shown.