Ultrasonic waves are used in SONAR instead of audible sound waves.

Sonar (originally an acronym for sound navigation ranging) is a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigate, communicate with or detect objects on or under the surface of the water, such as other vessels.

Working of SONAR: The ultrasonic waves travel through the water and after striking the target the beam is reflected from the seabed and is received by an under-water detector (mounted on the ship). The detector then converts the waves into electrical signals which are properly interpreted.

One way of detecting and locating submarines is by using passive acoustics or active acoustics. Submarines themselves are equipped with passive sonar systems, such as towed arrays of hydrophones that are used to detect and determine the relative position of underwater acoustic sources.

Unlike, Radio waves, Ultrasonic ones have a larger or longer wavelength. Water is a denser medium than air. Therefore, we can conclude that only Sonar is of any use in water, and that too not in air. The vice versa for Radar that can’t be used in water but only in dry air.

Although these sonar devices were firstly used for underwater measurements, they have subsequently been used for in-air measurements (i.e., in-air sonar sensors). These sensors spread mechanical waves through the air and wait for the echoes.

will SONAR even work out of water? I’m in a class right now that’s building a device that measures distances based on the echos from sound that it sends out. So yes, it works.

The sonar could have no detections for masonry walls, and up to 22 feet for single metal walls. The radar could have as little as 3 feet and as much as 45 feet depending on the amount of shadow-causing metal in the target’s path.

The invention of sonar changed the way that the seafloor is mapped. A combined transmitter and receiver, called a transducer, sends a sound pulse straight down into the water. The pulse moves down through the water and bounces off the ocean bottom. The transducer is able to pick up the reflected sound.

Time delay measurement accuracy is in the order of 0.05 ms. The water depth measurement inaccuracy could be mainly attributed to the estimation error in the average air temperature in the well, which is used to derive the average sound speed.

Ballistic-missile submarines are built to evade detection by making as little noise as possible. They move slowly—usually no more than 20 knots. They’re coated in anechoic tile, a rubbery substance that absorbs sound and prevents sonar detection. And nearly every moving part is isolated so that it won’t transmit sound.

Anechoic tile

1. To absorb the sound waves of active sonar, reducing and distorting the return signal, thereby reducing its effective range.
2. To attenuate the sounds emitted from the vessel, typically its engines, to reduce the range at which it can be detected by passive sonar.

The inertial guidance systems are accurate to 150 hours of operation and must be realigned by other surface-dependent navigational systems (GPS, radio, radar, satellite). With these systems onboard, a submarine can be accurately navigated and be within a hundred feet of its intended course.