What is principle of Echo Sounder operation?
- Echo sounder measures the depth of water by measuring the time for a pulse of energy to travel to the sea bed and back and work on the principle of reflection of acoustic energy.
- Short pulse of sound energy is transmitted vertically down from the ship.
- This pulse having been reflected from the sea bottom returns to the ship in the form of an echo.
- Travel time (t) taken for its return, depends upon the depth of water (d), and on the velocity of sound (v) through the water.
- Time taken (t ) = (2 x d) / v or d =(v x t)/2
- Performance of a sonar system depends on the accuracy with which the velocity of source propagation is measured.
The velocity of propagation is a function of temperature of water, pressure and salinity. The velocity is usually taken as 1500 meters/second for sea water at 13°C and atmospheric pressure.
