PROJECT TITLE :

Cross Correlation of Omnidirectional, Broadband Signals Scattered by a Random Pressure-Release Surface

ABSTRACT:

Expressions for the cross correlation of omnidirectional, broadband continuous-wave (CW) acoustic signals scattered by a pressure-release random surface are derived for each vertically and horizontally spaced hydrophones using the Kirchhoff approximation for the boundary values and therefore the Fresnel phase approximation. The resulting expressions for the spatial coherence are straightforward in type and require no approximations in the outline of the random surface. Because the surface becomes perfectly swish, the expressions scale back to the image resolution, therefore guaranteeing the proper limiting behavior. 2 narrowband models for vertical coherence were compared to experimental knowledge collected throughout a ocean check at the frequencies of 14, sixteen, 18, and 20 kHz with a most hydrophone spacing of one.four m. One model used the measured sound-speed profile (SSP) to estimate input parameters, and the opposite model assumed isospeed conditions. The agreement between the experimental data and also the model based mostly on the measured SSP is terribly good, and the agreement with the isospeed model is sort of as smart.