Multipath-based broadband source depth estimation using a single hydrophone

The sound field interference structure is analyzed in the reliable acoustic path (RAP) duct based on ray theory. We give the interference striation, which is defined as the line predicted by the approximate formulae and Bellhop model used in this paper (see e.g., Fig. 3 for more information). We observe that interference striation is resulted from time delay difference between the direct (D) path and the surface-reflected (SR) path of the broadband noise radiated from the underwater moving source. And interference striations turn to be tight with the increase of the source depth. Based on these observations, we propose a source depth estimation method by using a single hydrophone in the RAP duct. We set up a cost function which measures the matching degree between the interference striations (predicted by the approximate formulae and Bellhop model) and the sound field range-frequency interference structure (extracted from the sampled data of a single hydrophone). And we take the peak location of the outputted matching degrees as the source depth estimate. Numerical simulations show the effectiveness of the proposed source depth estimation method.