seade veealuste objektide tuvastamiseks helilainete abil
technique, that uses sound propagation (usually underwater, as in submarine navigation) to navigate, measure distances (ranging), communicate with or detect objects on or under the surface of the water, such as other vessels
Asdic, later known as sonar, was a secret device for locating submerged submarines by using sound waves. It was named after the Anti-Submarine Detection Investigation Committee. It consisted of an electronic sound transmitter and receiver.
