Coherence coefficient and interference structure of the convergence zone with broadband sound source

The core of array signal processing is to use the coherence between spatially distributed sensor received signals to achieve signal enhancement and parameter estimation. In the deep-sea environment, the coherence radius of the acoustic field directly determines the physical limit of the array design and the effectiveness of the processing algorithm. The interference fringes of the underwater acoustic field play a great role in sound source localization and propagation pattern recognition. Researchers generally consider the confluence region to be very coherent, the sound field strength is also strong, and there are no interference fringes. In this paper, it is found that in the converging region sound field excited by broadband sound sources, with the increase of the frequency bandwidth of the sound source, the correlation within the convergence region decreases, and the interference fringes between light and dark appear. This article analyzes the reasons for the above phenomenon in detail. The theories and conclusions were also validated in an ocean trial.