Ray-based analysis of a time-reversal mirror for underwater acoustic communication

Phase conjugation is a process whereby waves may be focused in an inhomogeneous and poorly characterized medium. Its application in underwater acoustics offers innovative solutions to active transmission problems, such as underwater digital communications. In this paper, the operation of a phase conjugate array is examined under simplified conditions, so that closed-form expressions for the pressure field may be obtained. These provide both insight into the energy focusing effect, and guidelines for designing actual arrays. Numerical results show that, from a communications perspective, signal regeneration at the focus offers significant intersymbol interference reduction. Equalization requirements at the receiver may therefore be substantially relaxed