High frequency source localization in a shallow ocean sound channel using frequency difference matched field processing

TitleHigh frequency source localization in a shallow ocean sound channel using frequency difference matched field processing
Publication TypeJournal Article
Year of Publication2015
AuthorsWorthmann BM, Song HC, Dowling DR
JournalThe Journal of the Acoustical Society of America
Volume138
Pagination3549-3562
Date Published2015/12
Keywordsacoustic noise; acoustic signal processing; array signal processing; underwater sound
Abstract

Matched field processing(MFP) is an established technique for source localization in known multipath acoustic environments. Unfortunately, in many situations, particularly those involving high frequency signals, imperfect knowledge of the actual propagation environment prevents accurate propagation modeling and source localization via MFP fails. For beamforming applications, this actual-to-model mismatch problem was mitigated through a frequency downshift, made possible by a nonlinear array-signal-processing technique called frequency difference beamforming [Abadi, Song, and Dowling (2012). J. Acoust. Soc. Am. 132, 3018–3029]. Here, this technique is extended to conventional (Bartlett) MFP using simulations and measurements from the 2011 Kauai Acoustic Communications MURI experiment (KAM11) to produce ambiguity surfaces at frequencies well below the signal bandwidth where the detrimental effects of mismatch are reduced. Both the simulation and experimental results suggest that frequency difference MFP can be more robust against environmental mismatch than conventional MFP. In particular, signals of frequency 11.2 kHz–32.8 kHz were broadcast 3 km through a 106-m-deep shallow oceansound channel to a sparse 16-element vertical receiving array. Frequency difference MFP unambiguously localized the source in several experimental data sets with average peak-to-side-lobe ratio of 0.9 dB, average absolute-value range error of 170 m, and average absolute-value depth error of 10 m.

DOI10.1121/1.4936856
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