一种小型机载低频UWB SAR的三级运动补偿方法

摘要

This paper derives the motion errors model of small size airborne low frequency ultra-wideband synthetic aperture radar (UWB SAR),and analyze the difference of the motion errors between the low frequency UWB SAR and the high frequency narrow band SAR as well as the reason of the traditional motion compensation (MoCo) method failure. To resolve this problem, a three-stage MoCo method is proposed. The procedure of the proposed MoCo method is as follows: At the first stage,removing the e-cho envelope error completely and the phase error partly by the MoCo based on the sensor data. Then,compensating the second-order phase error by the MoCo based on the Doppler chirp rate estimation at the second stage. At last, the residual high-order phase error is compensated by applying the autofocus algorithm in the image domain at the third stage,and the focused UWB SAR image is obtained. Experiment results on real data prove the validity of the proposed MoCo method.%本文建立了小型机载UWB SAR运动误差模型,分析了低频UWB SAR与高频窄带SAR间的运动误差不同点,找出了传统运动补偿方法失效的原因.为此,本文提出一种三级运动补偿方法.该方法的具体措施为:第一级,采用基于低精度传感器的运动补偿,消除回波包络误差和部分相位误差,提高回波数据距离弯曲校正精度；第二级,采用基于多普勒调频率估计的补偿方法,消除回波中的二次相位误差；第三级,基于图像域数据,采用自聚焦算法消除高阶相位误差,最终获得聚焦UWB SAR图像.实测数据成像结果证明了该运动补偿方法的有效性.