Sound Navigation and Ranging SONAR :: sonar sound wave waves

Missing Images SONAR, as it is most commonly known as has been around since the beginning of time. Animals have used this technique and survived because of it for millions of years. Among the most common are bats and dolphins. Daniel Colloden used a bell to measure the speed of sound underwater in 1822. After the Titanic sunk, the idea of using sound underwater to locate objects, primarily icebergs, was taken up by inventors. Lewis Richardson, a meteorologist, was the first to file a patent for an echo locator one month after the Titanic had sunk. In 1914, Reginald Fessenden made an experimental unit, which was able to detect icebergs within a two-mile range, but it could not determine the direction. During World War I, with the invention of submarines came the need to locate them. Research of underwater sound location was a primary focus for the British. Both the U.S. and Britain were researching what would be Sonar, and it was kept secret throughout the war. By 1922, units were being produced and by 1923, they were being equipped to naval vessels. Throughout the war, Britain referred to this underwater locator as ASDIC, which was the Anti-Submarine Detection Investigation Committee. This committee, however, never existed. The name was just a cover-up to keep the actual detector secret. The term SONAR came from the Americans, who used it as the equivalent of RADAR. The term ASDIC was terminated in 1948 when NATO was formed and signals were being standardized. Sonar utilizes sound propagation to detect objects, navigate, and communicate. Through acoustic location, Sonar can be used to find an object and tell how far away that object is. As shown above, a transmitter sends out a pulse of sound towards an object, the sound wave is then reflected off of the object and sent back to the source. The distance of the object is determined by the amount of time it takes for a reflection to return after the pulse is sent out. This can be affected by several factors such as the density of the media which the sound is traveling through and if the object itself is moving or not. To find the direction of the object, several receivers are used to signal when a reflection passes by them. The above picture shows an initial wave being sent out in all directions.