Identification of pick=up from acoustic mine sweepers - uses fact that sound radiated from underwater sources is more regular than from ships themselves

摘要

The system is for distinguishing between underwater sounds picked up from ships and those originating with sound-radiating underwater towed bodies intended to trigger acoustic mines or torpedoes in mine-sweeping or ships' defence operations. Two successive sections of the sound reception record are fed into memories and correlated with each other at predetermined intervals of time shifts which are much shorter than the lengths of the recorded sections. The correlation is much greater for rhythmically operated towed bodies than for ships. The circuit arrangement includes a hydrophone (1), amplifier (2), bandpass filter (3), threshold value unit (4), controllable switch (6), correlator (16) and comparator (18).