SONAR stands for Sound Navigation and Ranging. It is a technique based on sound propagation. It is used to navigate, communicate or detect objects under or on the surface of the water using sound propagation. This technology is helpful in exploring and mapping oceans as sound waves travel farther in the water than radar and light waves. SONAR helps NOAA scientists in developing nautical charts, detect underwater hazards to navigation, mapping of objects on the seafloor like shipwrecks.
SONAR can be of two types: Active and Passive.
Active SONAR: It mainly comprises transmitter and receiver. The transmitter generates and transmits high-frequency sound waves towards the target and then the receiver receives the vibrations which are reflected back from the target. Some sea animals like whales and dolphins use echolocation systems, which is similar to active sonar, to locate predators and prey.
Active SONAR:Passive SONAR: It has only a receiver to receive the sound waves. So, it only detects noises from underwater objects without transmitting the sound waves towards the targeted object. It detects sound waves coming towards the receiver and does not produce its own sound waves, which is an advantage for underwater military vessels and scientific missions that do not want to be found.
Passive SONAR: