基于图像对比度最优的频率步进ISAR成像方法

在频率步进高分辨ISAR成像中,目标的径向运动会带来距离多普勒耦合,从而对ISAR图像有较大的影响。提出了一种基于图像对比度最优的运动参数估计方法。该法分析了径向速度和径向加速度对多普勒像对比度函数的影响。通过构造相位补偿因子,在多普勒像中基于多普勒像对比度最优估计径向加速度。在径向加速度补偿后,在距离像中基于距离像对比度最优估计径向速度。进行运动补偿,利用RD算法实现了目标的高分辨ISAR成像。该方法具有运动参数估计精度高和计算量小的优点。仿真结果验证了方法的有效性。

ISAR imaging of stepped-frequency based on image contrast optimization

In stepped-frequency high resolution ISAR imaging radar, target motions produce the range-Doppler coupling which has a serious effect on the ISAR image. Consequently, a novel motion-parameters estimation method based on the image contrast optimization is proposed in this paper. Firstly, the effect of radical velocity and acceleration on Doppler profile contrast function is analyzed. Secondly, after constructing phase compensation term, the radical acceleration is estimated by the Doppler profile contrast function. After the radical acceleration compensation, the radical velocity is estimated by the range profile contrast function. Finally, after motion compensation and range-Doppler algorithm, the high resolution ISAR image can be obtained. This method has some advantages of high accuracy and fast computation speed. The experimental results demonstrate the effectiveness of the proposed method.