SONAR

SONAR, which stand for SOund Navigation And Ranging is a sensor system used by ships and submarines in order to detect other vessels and navigation hazards while operating on and under the water.

Modes

SONAR has two main modes of operation, Passive and Active.

Passive

Passive SONAR is the most often used method of SONAR that is employed by ships and especially submarines in order to detect and identify enemy vessels while "running silent." The basic operation of Passive SONAR if to have an operator listening very carfully to several acoustic hydrophones positioned on the outside of the hull of their ship. A good SONAR operator can tell by carefully listening to the sounds received by those sensors what vessels and objects are nearby their vessel. Most modern SONAR system make use of computers to assist in the identification of sounds in the water to help operators avoid making mistaken identifications using a sophisticated database of known undersea sounds.

Active

Active SONAR uses a sound emitted by the vessel, often referred to as a "ping," in order to gain precise information on a potential target. Like all forms of active sensors, it does have the disadvantage of alerting any other vessel nearby that another vessel is present. While Passive SONAR is able to identify the general location of a potential target, Active SONAR is required to gain a precise distance, vector and bearing of that target. The use of acoustic homing torpedoes usually means that active SONAR is not generally required in order to lock weapons and fire them at a target.