Sonar is an acronym for Sound Navigation and Ranging.

It is a technique and apparent for determining the location of an object by reflected sound waves. It is also a system for detecting and locating submerged objects and communication under water by transmitting a high frequency sound wave and collecting the reflected wave.

Uses: The Sonar principle is used to determine the depth of shallow bodies of water, to locate fish, under-water submarines, mines, wrecks and other obstacles. Initially, it was developed as a military instrument fro locating submarines. It is widely used for measuring water depth, and in Arctic regions for measuring ice thickness.

In active Sonar, pulses of high frequency sounds are beamed of a ship. The ‘ echoes’ are received by an apparatus by an apparatus that measures the time interval, and then computes the distance of reflecting objects. Where as passive Sonar detects sounds made by submarine engines or other sound producing objects.