You may have heard about submarines earlier. They are not visible from the surface of water. But have you wondered how this sonar mainly consists of two parts the transmitter and the receiver. Both these parts are submerged under seawater. The transmitter with the help of a transducer produces sound waves of high frequencies. These waves are called ultrasonic waves and cannot be heard by human ears. The transmits these waves in pulses in all the directions. Whenever these pulses strike some object inside the seawater waves are then receiver by the receiver. The time taken for the waves to reach the object the object and come back to receiver is measured. Half of this time when multiplied by the speed of sound in seawater gives the distance of the objects. This instrument consists a display device also which accurately shows the distance and the position of the of objects.
Submarines are detected by sending high frequency sound waves through sonar
Sonar however is not a foolproof system. The sounds produced by some aquatic animals like fishes and whales sometimes interfere with its transmissions and can be misleading about the position of the objects. The enemy submarines can be detected by this equipment and thus can be destroyed. These days there are various kinds of sonar being used for studding the objects under water. Sonar’s also help in large scale fishing by locating those spots where large groups of fishes are present. Nowadays blue green laser pulses are also being used for underwater detection of submarines and torpedoes. Laser based devices also work on the echo sounding principle just as sonar works.
