Sonar

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A sonar machine

Sonar is a machine that uses underwater sound waves to find other objects in the sea. A sonar can work by sending out sound and listening for echoes (active sonar), like a radar, or by listening for sound made by the object it is trying to find (passive sonar).

The basic parts of an active sonar are:

• the transmitter creates the sound waves.
• the hydrophone or hydrophone array converts the sound waves into electricity.

The first use of passive sonar was in 1490 by Leonardo da Vinci, when he put a tube onto water and listened. Active sonar was first used in 1917 by Paul Langevin. The word SONAR was created during the Second World War as an acronym for Sound Navigation and Ranging. This acronym replaced the British acronym ASDIC. The word is now thought by many people as a regular word, no longer as an acronym.

Sonar Media

• French F70 type frigates (here, La Motte-Picquet) are fitted with VDS (variable depth sonar) type DUBV43 or DUBV43C towed sonars.

• A sonar image of the Soviet Navy minesweeper T-297, formerly the Latvian Virsaitis, which was shipwrecked in December 1941 in the Gulf of Finland.

• ASDIC.png

  An ASDIC display unit from around 1944

• Sonar Principle EN.svg

  The principle of an active sonar

• Undersea bubble clouds.jpg

  Bubble clouds shown under the sea. From ref.

• TWIPS picture 2.png

  Comparison of Standard Sonar and TWIPS in finding a target in bubbly water. Adapted from ref.

• Variabel dybde sonar (VDS) på et af søværnets skibe af Thetis-klassen.jpg

  Variable depth sonar and its winch

• SH-3H HS-15 lowers AQS-13 sonar 1979.JPEG

  AN/AQS-13 dipping sonar deployed from an H-3 Sea King

• Watch floor.gif

  Lofargram writers, one for each array beam, on a NAVFAC watch floor