结合非线性CS算法的UWB-SAR运动补偿

Motion compensation for ultra wide-band SAR based on nonlinear chirp scaling algorithm

载机飞行不稳对SAR成像质量影响很大,对超宽带SAR系统尤其如此,提出了一种结合非线性CS算法的超宽带SAR运动补偿方法。通过采用引入高次相位补偿和非正交旁瓣抑制的改进非线性CS算法,减小了超宽带SAR成像中的相位误差。通过成像前的常规一阶运动补偿和距离徙动校正后的分块二阶运动补偿,有效补偿了超宽带SAR中的方位空变运动误差,提高了飞行不稳时的成像质量。该方法在运动补偿时考虑了方位空变运动误差随距离的变化,针对载机运动误差变化较快的情况也给出了处理办法。仿真和实测数据的处理结果验证了该方法的有效性。

In Synthetic Aperture Radar （SAR）, the deviation of the platform motion away from a straight line degrades the achievable SAR image quality. This problem is particularly acute for ultra wide-hand（UWB） SAR systems. In this paper, a new method based on nonlinear chirp scaling（NCS） algorithm is presented for motion error compensation in UWB-SAR. The high order phase compensation and non-orthogonal sidelohe suppression are introduced into the NCS algorithm, thus the phase error can be reduced by using the improved NCS algorithm in UWB-SAR imaging. To realize high resolution SAR images in the presence of motion errors, the conventional first-order motion compensation is implemented as a preprocessing step. After compensating the range cell migration, the data is divided into many sub blocks. Then the second-order motion compensation is implemented in each sub block in order to compensate the azimuth-varlant motion error. The variation of the azimuth-variant motion error with range is considered in this method. And the motion compensation method for the large deviation case is also presented. Lastly, both simulation and results of real data are provided to demonstrate the effectiveness of the proposed method.