SONAR is an acronym for SOund Navigation And Ranging, a technology that has been first developed by the military basically during World War I and intensively during World War II as a means of tracking enemy submarines under water. In fact, it was not until the invention of submarines that the military mindset realized the urgent need to invent an efficient way to track a submarine far too deep in the sea. Later on, this technique was developed and improved to serve a wide range of useful applications. The SONAR applies sound propagation to navigate, communicate with or detect objects on, or under the surface of the water—as in detecting submarines at the depth of the sea—or to have a clear dimensional image of a body in a confined vessel; such as checking on the baby during pregnancy.
SONAR is not really a modern day discovery. Man has discovered that it has been used for ages by several types of animals as a tool of survival. Man only needed to be a keen observant and develop a way to simulate this ability and develop a machine, or a device that can utilize it into useful applications.
How does SONAR work? The theory behind SONAR is pretty basic. SONAR is simply making use of an echo. When an animal or machine makes a noise, it sends sound waves into the environment around it. Those waves bounce off nearby objects, and some of them reflect back to the object that made the noise. It is those reflected sound waves that you hear when your voice echoes back to you from a canyon. Creatures such as whales, and specialized machines, can use reflected waves to locate distant objects and sense their shape and movement.
The range of low-frequency SONAR is remarkable. Dolphins and whales can tell the difference between objects as small as a shirt button 15 meters away, and they use SONAR much more than sight to find their food, families, and direction. The SONARs being tested by the military can travel thousands of miles, and could cover 80% of the Earth's oceans by broadcasting from only four points.
Today, we can name tens of significant applications being applied in various fields of life based on the SONAR principle. The military uses a large number of SONAR systems to detect, identify and locate submarines. In fishing, SONAR is used to locate and track schools of fish. Petroleum companies use what is called Depth Sounding, a technique that applies SONAR to determine the depth and the layout of land surface at sea depth during underwater operations. Satellite imaging is used combined with SONAR imaging during mapping of the seabed. SONAR is essentially used during inspection of dams and underwater pipelines and in marine archaeology and reef monitoring.
SONAR is an essential tool that serves different purposes. Needless to mention the significant role that SONAR plays in naval navigation systems.