Time reversal acoustic approach for non‐lethal swimmer deterrent.

Abstract

Protection against surface and underwater threats from swimmers constitutes one of the most challenging aspects of port security. The envisioned risk mitigation consist of passive acoustic detection and localization and active diver deterrent, which can be done by focusing high intensity acoustic waves. The main goal of this study is to explore the possibility of using the time reversal acoustics (TRA) sound focusing system for non‐lethal swimmer neutralization. This breakthrough technology enables the precision targeting of a hostile diver with minimum impact to the marine environments. The acoustic noise radiated by the diver is used to focus the acoustic energy, while the moving diver acts as an active self‐disclosing acoustic beacon. In a shallow water environment the radiated noise, direct and multi‐path interference, is rich and is exploited through the use of TRA. The effectiveness of the TRA focusing and the diver deterrence zone are modeled taking into consideration the frequency range, harbour depth, and geometry of the transducer array. The real diver noise and hydroacoustic signature parameters collected by Stevens Institute of Technology are used in the theoretical analysis. It is demonstrated that outside the focal region, the TRA system produces acoustic intensities that are not harmful for marine life.