逆合成孔径成像激光雷达成像算法

Imaging algorithm for inverse synthetic aperture imaging LADAR

逆合成孔径成像激光雷达是一种能实现运动目标超高分辨实时成像的雷达,它在发射激光信号的基础上,运用逆合成孔径原理对目标进行成像。但激光信号具有极高载频、超大带宽和极短波长的特性,传统的距离-多普勒算法不再适用。在对回波信号特征进行分析的基础上,利用重排维格纳分布和Hough变换对光外差探测后的信号进行时频分析以估计目标的运动速度,构造有效的补偿因子,完成了对回波信号的精确运动补偿,并进一步采用Keystone变换完成对目标散射点的越距离单元徙动校正,实现了对目标的高分辨二维成像。仿真实验验证了成像算法的有效性,并通过与微波波段逆合成孔径雷达的比较,证明了逆合成孔径成像激光雷达可实现对运动目标更快速、更高分辨的成像。

Inverse synthetic aperture imaging LADAR（ISAIL） is a radar system which can realize high resolution imaging for the moving targets.This radar realizes imaging with the laser signal and inverse synthetic theory.Due to the high frequency,large bandwidth and short wavelength of laser signal,conventional range-Doppler algorithm is not suitable here.In this paper,the characteristics of echo signal were analyzed;time-frequency analysis for the signal using the reassign smoothed pseudo WVD and Hough transform was carried out after optical heterodyne processing.Then,the velocity of target could be estimated and the echo signal could be compensated accurately.The Keystone transform was used to finish the migration through range cell compensation.Finally,the high-resolution two-dimensional imaging was realized.Simulation results show the effectiveness of the proposed algorithm,and demonstrate that the images achieved by the ISAIL system have much higher quality than those of the microwave ISAR system.