SONAR: Sound Navigation and Ranging
The full form of SONAR is Sound Navigation and Ranging. It is a technique that uses sound propagation (generally underwater, as in submarine navigation) to navigate, communicate or detect other vessels and detect objects below or on the surface of the water. This technology is useful for exploring and mapping the oceans since sound waves travel farther in water than radar and light waves. SONAR helps NOAA scientists develop nautical charts, detect underwater hazards to navigation, mapping of objects at the bottom of the sea like shipwrecks. The first recorded use of the technique was by Leonardo da Vinci in 1490, who used a tube inserted into the water to detect vessels by the ear. It was developed during World War I to combat the growing threat of submarine warfare, with a passive sonar operating system in use in 1918.
The Sound Navigation and Ranging (SONAR) can be of two types: passive and active. Passive sonar is essentially listening to the sound emitted from the glasses. It has only one receiver to receive sound waves. The active sonar emits pulses of sound and listening for echoes. It mainly comprises the transmitter and the receiver.