Topic : SONAR Module VI: Ultrasonics

Sonar stands for sound navigation and ranging. It works based on the principle of echo sounding technique.

Properties of Sonar :

1. Ultrasonic waves in sea water cannot be confused with any other noise as it is not heard by human ears.

2. Ultrasnonic waves have high frequency and hence it can be confined to a narrow beam. This property allows the ultrasonic beam to penetrate through a long distance in sea water without much loss of energy due to scattering.

                                      

Working of Sonar:

Piezo electric transmitter in the sonar generates short pulses of ultrasonic waves.  These sound pulses travel through the water and strike the object.

The sound pulse is reflected back and it is received by the ultrasonic receiver. The time interval between transmitted and received signals is noted by a cathode ray oscilloscope CRO.

By knowing the velocity v of the sound in sea water the distance of the object ‘d’ from the surface of water is calculated using the relation.

            Thus, the position of the moving object can be determined.

                               

Applications of Sonar:

1. Sonar is used to locate shipwrecks and submarines and in the bottom of the sea
2. It is used in fish finding applications and detection of fish shoals.
3. It is used in all merchant and military ships
4. It is used for seismic survey.