Penetration-free acoustic data transmission based active noise control

Active noise control (ANC) problems become more and more evident at low frequencies for underwater applications. Conventional wired techniques are ineffective since feedthroughs can compromise the structural integrity of ships, which would lead to physical isolation between active noise controller and secondary sources as well as error sensors. Wireless electromagnetic telecommunication method is unavailable due to the presence of Faraday shielding effect. In this paper, an acoustic alternative of controlling radiation noise of ships directly under the condition that the secondary sources locate outside the shell is determined. Penetration-free communication techniques are utilized for data transmission between active noise controller and sensors. Modulated signals are transmitted through metallic shell in the form of ultrasonic waves. Equalization algorithm is also added to eliminate channel distortion. All the complicated signal processing procedures can be accomplished in central controller located in the inner side of the ship. Optimized data transmission schemes for ANC are also investigated. Results show that the proposed method is promising for active noise control without physical penetrations.