What is principle of sonar?

Answer 1

Sonar (sound navigation and ranging) is the application of a sound wave propagated through some medium (like water) and the reception of reflected energy (the echo) to discover what is there.

Answer 2

When ultrasonics waves is transmitted through water, it is reflected by the object in the water and will produce an echo signal.

By noting the time interval between the generation of the us pulse and the reception of the echo signal, the distance of the object can be easily calculated.

Answer 3

The need of "real" sonar dates back to the early 1900's. It was applied to hazard detection. When waves break against shore (or the sides of an iceberg - think Titanic), they can be heard. The sound travels in water better than in air. If you can hear wave action, that is, if you can hear waves breaking against something, it's time to get real sharp with your helm controls. And if you can know which way the sound is coming from, you can avoid that area and the breaking waves.

Oceanographers all over the world apply it to the study of all kinds of stuff on the bottom. Sonar also has uses in looking at everything between (and including) the bottom itself and the waves on the top of the ocean. Those who look for the wrecks of ships have made popular video presentations about their exploits. The discovery of Titanic was widely viewed.

Geologists can use sonar mapping to look below the ocean bottom to learn something about the underlying rock structures. Oil companies have been using this application of sonar for years.

Fishermen use it big time. Commercial fishing vessels are uniformly equipped with it. They want to know where to fish and where not to risk their nets because of snags and terrain. There are a lot of sport fishing rigs that have the technology aboard. (It is attractively priced owing to advancements in electronics and in manufacturing technology. The units can be well made and can be marketed at a "good" price.) A fisherman can locate fish habitat that may be productive using sonar mapping, and can relocate it upon a return trip.

Imaging and mapping using acoustics is common in the medical field. Medical imaging with (ultra)sound represents the broadest application of sonar and sonography. There are hundreds of thousands of the devices in use around the world.

Industry uses sonography in non-destructive testing to "look through" materials for defects. It can be used in the assessment of the structural integrity of a number of solids. Sonar (sound navigation and ranging) has many uses. It is used by the military to look for submarines (one of the reasons for which it was originally developed). It is also used by the military and by ocean scientists to find out the depth of water and to map the contours of the ocean bottom. Sonar is also used in a variety of other ways by oceanographers to study the everything from the ocean bottom to the waves on top. The technology can obviously be applied to the study of ocean life. Sonar can also be used to look "below" the ocean bottom at the geologic structures below the ocean floor. Petrochemical explorers and others apply this technology.

Certainly sonar has gained notariety for being useful to find things lying on the ocean floor. (A number of famous ships that sunk have been located with it, like Titanic.) And it is used by fisherman for locating fish and for mapping terrain on the bottom of lakes or offshore fishing sites. Imagine boating out into open water to find that "spot" and not having sonar. Even with GPS, being able to "see" the bottom would put fishermen at a great advantage over others not equipped.

Sonar is used daily in the medical world to scan the inside of the human body and to look at unborn babies. Medical imaging is the most popular application of sonar.

A link is provided to the Wikipedia article on sonar.

Answer 4

for a dolphin to detect any incoming treats.... submarines to detect the object or obstacles ahead. and also ships on the surface to detect submerged submarines

Answer 5

A sonar device sends a burst of ultrasound waves to reflect and locate stuff.