基于FFT的ISAR成像快速包络对齐方法

包络对齐是逆合成孔径雷达（Inverse Synthetic Aperture Radar,ISAR）成像中运动补偿的关键技术之一。现有的互相关法和最小熵法无法兼顾对齐精度和运算效率,不能很好地满足ISAR实时成像的需要。推导证明了两信号时域的圆周相关等于其频谱的共轭相乘,再基于改进的互相关法,提出了一种包络对齐快速算法,利用FFT实现快速圆周互相关运算,并结合插值处理提高包络对齐精度。理论分析和仿真实验都表明,该方法可同时实现较高的对齐精度和运算效率,能够满足ISAR实时成像的要求。

A Fast Envelope Alignment Algorithm for ISAR Imaging Based on FFT

Envelope alignment is one of the key technologies in inverse synthetic aperture radar（ ISAR） motion compensation.The existing correlation algorithm and the minimum entropy algorithm fail to realize high alignment accuracy and computation efficiency simultaneously,which are not suitable for real time ISAR imaging. The conclusion,which the circular correlation between two signals in the time domain equals to the conjugate multiplication between their spectra,is deduced and verified. Based on the improved correlation algorithm,a fast envelope alignment algorithm is proposed. Circular correlation is implemented by FFT in the new algorithm,and combined with data interpolation,high alignment accuracy is obtained. Theoretical analysis and simulation experiments show that the proposed algorithm can achieve high alignment accuracy and computation efficiency simultaneously,which is applicable to real time ISAR imaging.