- sonar, echo sounder, asdic - a measuring instrument that sends out an acoustic pulse in water and measures distances in terms of the time for the echo of the pulse to return; sonar is an acronym for sound navigation ranging; asdic is an acronym for anti-submarine detection investigation committee
--1 is a kind of measuring instrument, measuring system, measuring device; navigational instrument
--1 is a part of submarine, pigboat, sub, U-boat
--1 has parts: pinger; pulse generator