基于参数估计的步进频ISAR成像运动补偿方法

Stepped frequency moving compensation method of ISAR imaging based on estimating of target moving parameters

分析了基于步进频雷达运动目标的回波信号模型,讨论了目标运动对ISAR成像的影响,针对当目标有速度或加速度时会造成高分辨距离像移位和畸变,并使二维像散焦的情况,提出了一种基于高斯包络线性调频信号自适应分解、高分辨距离像互相关法及多普勒横向像最小熵法的运动补偿算法。该算法利用高斯包络线性调频信号自适应分解得到回波多普勒调频率和目标运动的加速度,通过距离像移动对目标运动速度进行初估计,并用高分辨距离像互相关法及多普勒横向像最小熵准则提高目标速度及加速度的估计精度,然后进行运动补偿。该算法计算量小,估计精度高,仿真结果验证了它补偿效果好,能获得清晰的ISAR像。

The echoed signal model of a stepped frequency ISAR and the moving target affects to ISAR imaging are analyzed. The velocity and acceleration of moving targets would result in translation and aberrance of high resolution range profile and blurring of ISAR images. Based on this, a new moving compensation approach is proposed. This approach obtains echoed signal chirprate and its rough acceleration by the adaptive Gaussian chirplet decomposition method, estimates the rough velocity using the translation of high range profiles, and improves the estimating accuracy based on the correlation method of high resolution range profiles and minimal entropy criterion of Doppler profiles. The target moving parameters estimated are used to compensate the echoed signals. Such method has advantages of fast computation speed and high accuracy, the numerical simulation proves its good efficiency.