Large‐area acoustic field characterization in shallow water by using broadband ship noise measured on the New Jersey Shelf

Acoustic signals emitted by ships of opportunity (merchant ships) are simultaneously recorded on three vertical line arrays (VLAs) during the New Jersey Shelf RAGS03 experiment. Although the single‐receiver correlation between the VLAs (separated by ∼10 km) was very low, a Bartlett correlator between each VLA produced well‐defined striation patterns. Waveguide invariant theory has been applied to Bartlett correlator output to obtain range ratios of the noise source to the receiver arrays [A. Turgut, J. Acoust. Soc. Am. 118, 1857 (2005)]. Trajectories of striations are identified by the Hough transform that converts a difficult global detection problem in the image domain into a simpler local peak detection problem. The striation patterns are also observed when the Bartlett correlator is applied to different time segments of the noise data. This provided an opportunity of obtaining reference acoustic field data for winter conditions if the location of the noise source is known a priori. Analysis of the RAGS03 data indicates the feasibility of source localization and acoustic field characterization by using broadband noise signals emitted by distant surface ships. [Work supported by ONR.]