ASA 124th Meeting New Orleans 1992 October

4pUW12. Estimation of acoustic source signatures in an ocean waveguide.

S. Finette

P. Mignerey

Acoust. Division, Naval Res. Lab., Washington DC 20375

Some experimental results are presented on source signature extraction using vertical array data obtained from the acoustic field emitted by a point source in a deep ocean waveguide. Passively sensed field data obtained with a large aperture vertical array is processed by wideband, coherent, and incoherent matched-field methods, and a multichannel deconvolution approach in order to localize the source and reconstruct its temporal signature [P. Mignerey and S. Finette, J. Acoust. Soc. Am. 92, 351--364 (1992)]. A wideband normal modes code was implemented on a fine-grained parallel computer and used to calculate both the replica field vectors and the deconvolved estimates of the source signature. Signals in the band 25--110 Hz are processed for sources located at either the first or second convergence zones, approximately 48 and 97 km from the array. Normalized cross correlations between the measured signatures and their deconvolved estimates indicates that faithful reconstructions of the source signature can be obtained by processing a subaperture of the array data. The method depends on reliable estimates of the ocean Green's functions linking the source and receivers, which in turn depend on good environmental knowledge concerning the ocean waveguide properties. [Work supported by ONR and NRL.]