W波段ISAR包络对齐方法研究

在ISAR成像处理中，目标整体在距离方向的位移会使散射点的回波无法落在相同的距离单元内，造成成像结果的散焦，因此采用包络对齐的方法对该位移进行补偿。然而在W波段的ISAR包络对齐处理过程中，较高的分辨率会使回波包络在成像时间内发生变化，导致传统方法产生对齐误差。针对该问题，提出了一种使用Keystone变换进行包络规整的方法来提高包络对齐的准确度。在Keystone变换之前，使用了目标重心跟踪及补偿的方法来实现回波信号的相干化。实验结果表明，通过包络规整处理，成像结果的极值点强度，图像熵以及图像对比度都得到了较大的提升。

Study on W Band ISAR envelope alignment

The movement of target in range direction will make the echo of scatters shift from range cell, and this will cause blur in ISAR imaging process. Thus, the envelop alignment is used to compensate this shift. However, the high resolution in W Band ISAR will cause the envelop to change its shape during the imaging period. This will cause error in traditional envelop alignment methods. Therefore, a new envelope regular method based on Keystone transform is proposed to increase the accuracy of envelop alignment. Before the Keystone transform, a target center track method is used to make the return signal coherent. The simulation results show that the peak value, entropy and contrast of image are improved by applying this method.