Towed sonar arrays

摘要

Low frequency vibration induced noise is reduced in a towed sonar aray of the type comprising n oil-filled modules 10 joined end to end with each module housing m hydrophones by arranging that at low frequencies the outputs from all the hydrophones in a module are added together at 301...30n with uniform weighting and without relative phase delays so as to form respective single channel outputs. Beamforming is carried out by applying phase delays W 1.... W n to form a beam in a predetermined direction. High modulus internal strength members are included in each module to resist anti-phase vibration of the couplings at the end of the module. The hydrophone spacing and the coupling lengths are both made small compared to the module length to improve vibration noise reduction.