Measuring ship-radiated noise level via vertical linear array based on virtual time reversal mirror

By adopting the virtual time reversal mirror (VTRM) technique, the ship-radiated noise measurement formula using vertical linear arrays is derived based on the underwater acoustic models, and a method is proposed to measure the ship-radiated noise level which is generally affected by multi-path transmissions in the underwater acoustic environment. Firstly, the transfer functions between the source (the noise-radiating ship) and the measuring hydrophones are calculated by using the SCOOTER model based on wavenumber integration techniques with given environment parameters. And then, the source signal is retrieved by applying the transfer functions to the received signals and carrying out time reversal processing, in order to eliminate or alleviate the effects caused by multi-path transmission. Numerical simulations in a typical shallow water environment demonstrate the effectiveness of the proposed method. When the number of the measuring hydrophones satisfies a certain requirement, the difference between the source level estimated by VTRM method and the origin source level is less than 1 dB.