BROAD-BAND SOURCE SIGNATURE EXTRACTION USING A VERTICAL ARRAY

Source signatures have been extracted from acoustic data received on a large vertical array. Multichannel deconvolution methods were used in conjunction with broadband coherent and incoherent matched-field proc essors for source signature reconstruction. The signatures were genera ted by broadband (25-110 Hz) sources located near the first and second convergence zones, approximately 48 and 97 km from the array. Cross-c orrelation coefficients between known source signatures and deconvolve d estimates indicate that faithful reconstructions of both magnitude a nd phase can be obtained. Use of incoherent noise components from the main diagonals of cross-spectral density matrices produced correlation coefficients ranging from 0.77 to 0.93. Degradation primarily appeare d as increased noise in the reconstructed signature. Attempts to inclu de the full spatial coherence of the ambient noise by using off-diagon al matrix components, resulted in correlation coefficients approximate ly 10% lower. This effect is caused by nonstationarities in the noise field which preclude using an ergodic hypothesis to obtain statistical ly reliable temporal averages for the cross-spectral density matrices.