Acoustic Calibration in Shallow Water: Theory, Simulations, and a Preliminary Site Study
2006
Porter, R. P. | Rouseff, D. | Fox, W. L. | Siderius, M.
Original contains color plates; All DTIC/NTIS reproductions will be in black and white.
Show more [+] Less [-]Initial research on a new method for characterizing the acoustic properties of a shallow water site is documented. The method uses moored vertical transmitting and receiving arrays. By combining the array data with limited environmental data, the measured acoustic data are extrapolated to predict the coherent field and transmission loss over an extended region. Motivation for the problem and approach is given, and the theory of the extrapolation algorithm is presented. Numerical examples demonstrate the relative insensitivity of the method to knowledge about the sediment. An experiment to test the extrapolation procedure is contemplated for the summer of 1994, and a possible site off the Massachusetts-New Hampshire coast is considered. Using archival sound speed data and bathymetry, transmission loss is calculated for a region with a gently sloping bottom and is compared with extrapolated predictions. The extrapolation method is shown to be relatively insensitive to sound speed variability in the water column, but sensitive to changes in depth. Element spacing of greater than one-half the acoustic wavelength in both the transmitting and receiving arrays is shown to be adequate for some cases. Ocean acoustics, Acoustic calibration, Normal mode theory, Huygen's principle, Shallow water propagation, Field extrapolation
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