ROBUST WIDE-BAND MATCHED-FIELD PROCESSING WITH A SHORT VERTICAL ARRAY

This paper addresses the problem of matched-field passive localization of broadband underwater acoustic sources with a short vertical array. In previous work, incoherent averaging of narrow-band Bartlett ambigu ity surfaces has been proposed to improve the robustness of matched-fi eld processing (MFP) to environmental uncertainties. While computation ally efficient, the effectiveness of this approach is dependent on the type of environmental mismatch present. In this paper, to provide rob ust source localization performance for short arrays, an alternative w ideband MFP method is proposed which utilizes the fourth-order statist ics of the data. The method is ''coherent'' in that it exploits cross- frequency dependencies in the random acoustic channel response. The pr oposed coherent wideband minimum variance method with environmental pe rturbation constraints (MV-EPC) consists of minimizing the squared out put power of a beamformer subject to constraints defined across the si gnal band. The constraints are designed to provide robustness over an ensemble of random environmental realizations. Monte Carlo simulation results using a canonical shallow-water scenario indicate that the coh erent wideband MV-EPC method yields improved probability of correct lo calization performance versus-incoherent averaging of narrow-band Bart lett ambiguity functions with a short array above a threshold signal-t o-noise ratio. (C) 1997 Acoustical Society of America.