Fast estimation of distance between two hydrophones using ocean ambient noise in multi-ship scenarios

Abstract

Accurately estimating the bearing of a target with two hydrophones requires knowing the precise distance between them. However, in practice, it is difficult to measure this distance accurately due to the influence of current. To solve this problem, we propose a method for extracting the time-domain Green’s function between two points in multi-ship scenarios and for extracting the time-domain waveform arrival structure between two hydrophones in real-time based on long samples of ship radiation noise cross-correlation. Using the cross-correlation function of the radiated noise from any ship located in the end-fire direction of the two hydrophones, we can estimate the distance between the hydrophones in real-time. To verify the accuracy of our estimation, we compare the result of azimuth estimation with the actual azimuth based on the azimuth estimation of a cooperative sound source in the maritime environment. Our experimental results show that the proposed method correctly estimates the distance between two hydrophones that cannot be directly measured and estimates the position of a cooperative sound source 4 km away with an average deviation of less than 1.2°.