What is echo-ranging?

Explanation

SONAR employs ultrasonic waves for its working. Powerful pulses of ultrasound are sent out at regular intervals from a transmitter mounted on a ship. These pulses are intercepted by an object or the sea bottom, and get reflected. The reflected sound (or echo) is detected by underwater receiver mounted on the ship known detector. The time interval between transmission an reception of the ultrasonic signal is recorded. Knowing the speed of ultrasound in sea water and the interval between transmission and reception the ultrasound signal at a point, the depth of the sea or any other obstacle at that point can be determined. Let, Depth of the sea = d
Speed of sound in sea water= v
Time lapse between transmission and reception signal= t
So, Time taken by the sound to travel distance, `d= (t)/(2)`
Then, Depth of the sea, `d= v xx (t)/(2)`