Sound navigation and ranging is a technique
that uses sound propagation to communicate with or detect other vessels. There are 2 kinds of sonar: active
. Some uses of sonar are acoustic location and of measurement of the echo characteristics of targets in the water. Acoustic
location in air was used before the introduction radar. Sonar is also used for robot navigation, and SODAR
is an upward looking in-air sonar used for atmospheric investigations. The word sonar is also used for the equipment used to generate and receive the sound. Frequencies used in sonar range from very low to extremely high. The study of underwater sound is also known as underwater acoustics
or hydro acoustics
Sonar is crucial to naval forces through out the world to track and monitor other countries submarine activities and movements. There is also numerous underwater stations that aid in ocean temperature and and tide changes.