Abstract:

The time reversal mirror (TRM) imaging and self-focusing concept was tested numerically by using a newly developed 3-D full-wave propagation model and a stochastic model of bottom heterogeneity. The 3-D propagation model was used to calculate pulse scattering from an attenuating inhomogeneous seabed and buried objects. Two-dimensional seabed roughness and three-dimensional sediment volume inhomogeneities were modeled by using the Von Karman type of spectra with proper statistical parameters which were obtained from stereo photography, sediment tomography, and chirp sonar measurements. A parametrical study was performed to identify proper choice of pulse shape, time gating, phase-screen backpropagation, and amplitude correction for selected distributions of multiple scatterers, burial depths, sediment layering, and statistical properties. Numerical simulations indicated that the TRM should perform well for detection of 3-D objects buried in the seabed. Finally, based on the results of the parametrical study, design criteria of a TRM field experiment are also discussed.