Separation and extracting the interference structures of moving acoustic sources with a single vector hydrophone

Abstract

Waveguide invariant, which describes the striations in the acoustic spectrograms produced from underwater broadband source due to constructive and destructive interferences of propagating modes, has been applied from monitoring acoustic fluctuations to assisting in various types of signal processing. Waveguide invariant extraction is the critical step for these applications. Though many image processing methods have been exploited to process the interference striations effective, the performances of them descend and inaccuracy parameters provided while there exists multiple interference structures. Array beamformer is feasibility to separate the interference structures. However, the utilization of array is expensive and inconvenient in many situations. In this paper, a method by single vector hydrophone is presented to separate and extract the interference structures of moving acoustic sources. Cross spectrum processor of acoustic pressure and combination acoustic particle velocity is used to achieve the spectrum of each source by rotating driving direction to the bearing of other sources' synthesis energy flux. The trajectories equation of striations is derived, and the Hough transform method is also utilized to extract the waveguide invariant and the ratio of the Closest Point of Approach (CPA) range to velocity of the source. In addition, the trail data, which recorded two surface ships passing by, collected by single hydrophone during an experiment at the South China Sea is analyzed. Finally, the simulated data and experimental filed data are processed to examine the proposed method.