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

Abstract

-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.

Passive Localization of Multiple Sources Using Widely-Spaced Arrays With Application to Marine Mammals

“…Figure 3 shows a 3D display of the resulting track. For humpback whales our simulations indicate [7] that our PWS processor is more robust with respect to environmental mismatch and noise than the Bartlett (linear matched-field) processor and the PWW processor. This is as expected, since spectrograms are less sensitive to changes in the environment than waveforms.…”

“…Conventional matched-field techniques may also be insufficient because they are limited to low frequencies and/or rely on line arrays [5,6]. To deal with the unknown nature of the sources, we developed the pair-wise waveform (PWW) processor [7]. Our pair-wise spectrogram (PWS) processor [7] extends the PWW processor by using spectrograms instead of waveforms.…”

“…To deal with the unknown nature of the sources, we developed the pair-wise waveform (PWW) processor [7]. Our pair-wise spectrogram (PWS) processor [7] extends the PWW processor by using spectrograms instead of waveforms. Spectrograms allow us to use high frequencies, which are sensitive to environmental mismatch and noise.…”

“…Simulations were run for numerous environments and source/receiver configurations. The theory and initial simulations have been published in an OES Newsletter [7].…”