逆合成孔径激光雷达相位误差补偿算法

Algorithm of Phase Error Compensation for Inverse Synthetic Aperture Ladar

由于发射信号波长极短,目标或平台的微小振动将严重影响逆合成孔径激光雷达(ISAL)的成像效果。同时受激光调制技术的限制,ISAL发射脉冲信号的初始相位存在随机相位误差,这也对ISAL成像造成了极大的影响。现有的相位梯度自聚焦(PGA)算法无法补偿高频振动产生的相位误差;由于目标相对雷达转动分量的影响,空间相关算法(SCA)对补偿上述ISAL中的相位误差效果有限。为解决上述问题,将PGA算法与SCA方法相结合,提出了PGA-SCA相位补偿算法,通过循环移位和加窗处理消除了相邻回波间目标转动的影响。仿真结果表明,PGA-SCA能有效补偿上述两种相位误差,并获得聚焦良好的ISAL图像。

Since the transmitted signal of inverse synthetic aperture ladar （ISAL） has a very short wavelength, even the weak vibration of the target or the platform will seriously corrupt the ISAL image. In addition, existence of random phase error of the initial phases of the transmitted pulses of ISAL will greatly degrade ISAL images due to the limitation of the laser modulation technology, which also results in a defocused image of ISAL. The phase gradient autofocus （PGA） algorithm fails to compensate the phase errors induced by a high-frequency vibration; meanwhile, the spatial correlation algorithm （SCA） has a limited function on compensating the phase errors because of the relative rotation between the target and ISAL. Combining PGA and SCA, a new phase error compensation algorithm, which can be named PGA-SCA, is proposed. The effect of the relative rotation is eliminated by a circular shifting and windowing operation. Simulation results show that, the proposed algorithm is effective in correcting the phase errors and capable to generate a well-focused ISAL image.