Sonar was invented based on the positioning system of dolphins, which uses the propagation and reflection characteristics of sound waves in water to conduct navigation and ranging technology through electroacoustic conversion and information processing. This technology is used to detect underwater targets. Perform detection (existence, location, nature, direction of movement, etc.).
Sonar is the main technology used by navies of various countries for underwater surveillance. It is used to detect, classify, locate and track underwater targets; conduct underwater communications and navigation, and ensure the tactical maneuverability of ships and anti-submarine aircraft and use of weapons in water.
In addition, sonar technology is also widely used in torpedo guidance, fish detection, offshore oil exploration, ship navigation, hydrographic survey, and survey of seabed geology and landforms.
Extended information:
Sonar is not a patent of humans. Many animals have their own sonar. Bats use their throats to emit 10-20 ultrasonic pulses per second and use their ears to receive their echoes. With this "active sonar", they can detect very small insects and metal wire obstacles with a thickness of 0.1 mm.
Insects such as moths also have "passive sonar" and can clearly hear the ultrasound of bats 40 meters away, so they are often able to evade attacks. However, some bats can use high-frequency ultrasound or low-frequency ultrasound beyond the listening range of insects, so that the hit rate of catching insects is still high.
Therefore, animals also engage in "sonar warfare" like humans.