Pair-wise processing of spectrograms for localization of multiple broadband CW sources

A pair-wise processing algorithm has been developed to localize broadband sources in shallow water. A simple sparse hydrophone array with number of elements roughly equal to the maximum number of sources is used. The sources can be continuous-wave (i.e. no onset times), and no previous knowledge of source signatures is required. The processor is spatially coherent and partially frequency coherent. Simulations show considerable improvement over conventional (i.e., frequency incoherent) matched field techniques under realistic noise conditions, with environmental mismatch and multiple sources. Spectrograms have been incorporated into the algorithm to make use of higher frequencies at greater ranges. Our work is motivated by the problem of localizing multiple singing humpback whales, and recordings of humpback whale song from the Pacific Missile Range Facility in Hawaii are being analyzed.