星载分布式InSAR基线定标新方法

A New Method of Space-Borne Distributed InSAR Baseline Calibration

为了解决星载分布式干涉合成孔径雷达三维基线的高精度定标问题,提出了一种基线定标新方法。首先,该方法将辅雷达多普勒方程与辅雷达距离改化方程相结合,形成基线定标模型,再基于地面控制点,采用最小二乘迭代解算基线三个轴向误差。与基于辅雷达距离改化方程的基线定标模型相比,该基线定标模型优化了法方程系数矩阵条件数,减小了矩阵的病态程度,提高了定标精度。然后,根据基线定标实际上是利用多个地面控制点交会出基线矢量,以及增大交会角可提高交会精度的原理,给出了控制点布设策略,即在近、远距端两侧布设控制点。与均匀布设控制点方式相比,该方式能显著提高定标精度和稳健性。最后,利用星载分布式干涉合成孔径雷达仿真数据进行基线定标实验,先后开展基于不同控制点数量、不同控制点精度、不同控制点布设策略的基线定标实验。实验结果表明,该方法能实现三维基线高精度定标,对跨轨、顺轨、径向基线的定标精度能达到毫米级,可为星载分布式干涉合成孔径雷达基线定标提供一种新途径。

To solve the problem of high precision calibration of three-dimensional baseline of space-borne distributed interferometric synthetic aperture radar(InSAR),a new method of baseline calibration is proposed.Firstly,this method combines the slave radar Doppler equation and the slave radar distance modification equation to form the baseline calibration model.Based on the ground control points,the least square iteration is used to solve the baseline three axial errors.Compared with the baseline calibration model based on the slave radar distance modification equation,the baseline calibration model optimizes the coefficient matrix condition number of the normal equation,reduces the morbidity of the matrix,and improves the calibration precision.Then,according to the baseline calibration,the baseline vector is actually used to intersect by the ground control points,and the intersection angle can be increased to improve the accuracy of the intersection.The control point layout strategy is given,that is,the control points are laid separately at the near and far ends of the radar footprint at ground.Compared with the way of laying control point uniformly,we can significantly improve the calibration precision and robustness.Finally,the spaceborne distributed InSAR simulation data was used to carry out the baseline calibration experiments based on different control points number,different control points precision,and different control points layout.The experiments show that the new method can achieve high-precision result of three-dimensional baseline calibration,namely,millimeter-scale in cross-track,along-track and radial baseline direction respectively,which can provide a new way for the baseline calibration of spaceborne distributed InSAR.