利用环境噪声互相关实现散射体无源成像

Passive imaging of scatterers based on cross-correlations of ambient noise

最近研究表明利用环境噪声的互相关可以恢复两点之间的时域格林函数(声脉冲响应),这一原理在文献中被称为格林函数恢复。基于此原理,通过对多个传声器所接收的环境噪声进行互相关处理,获取与散射体相关联的散射波的到达时延信息,结合最小二乘反演算法和改进克希霍夫移位算法,分别获得道路交通噪声场中石柱以及海浪噪声场中塑料桶的空间位置,且其估计结果与实际测量相一致。实验结果表明将环境噪声作为探测信号进行散射体无源成像是可行的。这为设计室内无源声监测系统以及通过海洋环境噪声实现对水中静默目标成像提供了新思路和有益参考。

Recent studies have demonstrated that Green＇s function between two points can be retrieved from cross- correlation functions of ambient noise recorded at these two points. Green＇s function retrieval is applied to road traffic noise and beach surfing noise. Scattered arrival waves are retrieved from cross-correlations of noise recorded at pairs of microphones. Through the least squares approach and Kirchhoff migration algorithm, the feasibility of passive imaging of scatterers with ambient noise around kilohertz is experimentally demonstrated for the first time. The accuracy of scatterer passive imaging is confirmed by comparison with ground truth measurements. The experimental results indicate that Green＇s function retrieval using cross-correlations of ambient noise can be a new way for the design of indoor passive acoustic monitoring system, and provides a good prospect of imaging silent target in water by using ocean ambient noise.