Noise control composite

摘要

A composite for use on submarines and surface craft for controlling self-generated noise when listening with sonar. The composite includes two layers of PVF2 transducers separated by a layer of phase shifting or absorbing material. The inner transducer senses noise from the ship and subtracts this from the signal from the outer transducer representing noise plus the desired signal. In a second mode the sensed noise is regenerated through the outer transducer 180 DEG out of phase to cancel the noise and allow more accurate detection.