基于VMD-ICA的水下激光雷达抗散射信号处理方法

Anti-scattering signal processing method of VMD-ICA based underwater lidar

提出一种基于变分模态分解(VMD)与独立元分析(ICA)相结合的水下信号处理方法.该方法运用VMD将一组回波信号分解为多组按照频率高低顺序排列的本征模态信号.然后,将这些模态信号作为ICA的观测矩阵,以确保分离所得目标回波信号的完整性.该方法提出将分解所得的各层模态信号与原信号进行相关性和信杂比比较,以确定其分解层数.应用ICA方法对散射与目标回波进行分离,从而恢复强散射水体中的微弱目标回波,大大提高其测距精度.进行不同衰减长度水体的532 nm调频连续光水下测距实验.经实验验证,该信号处理方法在激光输出功率2.3 W时,成功实现对9个衰减长度内目标的测量,使用算法将测距精度由16 cm提升至5 cm以内.

This paper proposes an underwater signal processing method based on the combination of variational mode decomposition(VMD)and independent component analysis(ICA).In this method,the VMD is used to decompose a set of echo signals into groups of eigenmodal signals arranged according to the order of their frequencies.These modal signals are then used as an observation matrix for ICA to ensure the integrity of the separated target echo signals.In this method,the correlation between the decomposed modal signals and the original signal is used to select the signals which are used as input matrix rows for ICA.The signal-to-clutter ratio is used to determine the number of decomposed layers.The ICA is used to separate the scattering and target echoes,so as to recover the weak target echoes in the strongly scattered water and greatly improve the ranging accuracy.A 532 nm intensity-modulated continuous wave(CW)laser is used in the underwater ranging experiments.The attenuation coefficient of the water is changed by adding Mg(OH)2,ranging experiments are carried out at different attenuation lengths.The experimental results show that the signal processing method can be used to successfully measure the target within 9 AL(attenuation length)when the laser output power is 2.3 W,and the ranging accuracy is improved from 16 cm to less than 5 cm by using the algorithm.The proposed method can be applied to underwater lidar application in turbid water and long distance ranging underwater where the scattering dominates the echoes.