- Acronym for SOund Navigation And Ranging
- Uses sound waves to navigate, communicate with, or detect objects under water
- The term SONAR was first developed and used by American scientists in the 1930s
Leonardo da Vinci first studied techniques of object detection under water in 1490. The first two patents for underwater echo transmitters were filed in Britain and Germany within a year of the Titanic sinking in 1912. The disaster could have been prevented if the captain and crew had known where the size and shape of icebergs beneath the water’s surface.
The Allies during WWI had been searching for ways of locating German submarines, to which the genius Nikola Tesla suggested using sound waves, with which he had experimented. Tesla’s advice was not immediately taken, but various experimental devices were being built and tested in secret.
A practical device was first constructed in 1916 by Canadian Robert William Boyle. France and Britain used prototype devices experimentally during WWI, and fully-functional devices were being used liberally during WWII.
There are two types of SONAR activities.
- Passive SONAR occurs when an agent is using a detector simply to listen for the sound waves being emitted in his direction. This is useful for developing a large-scale picture of what is going on in the surrounds, but very few specifics can be gleaned from this information.
- Active SONAR occurs when a signal is directed outward toward a targeted area and an echo is received. Based on the time the signal takes to return to the receiver and the pattern of the echoed signal, active SONAR can determine the location of an object, its size and shape, and (if repeated signals are sent) its speed and direction of movement. The echoed waves can essentially create a 3D map of target area.
The use of SONAR technology led to developments in automated torpedo navigation, airplane navigation and detection, meteorological measurements, traffic and projectile (i.e. baseball) speed detection, mine investigation and locating, commercial fish finding, sea depth measurement, and even as a prosthesis for the visually impaired.