What is sonar?

  • (noun): A measuring instrument that sends out an acoustic pulse in water and measures distances in terms of the time for the echo of the pulse to return; sonar is an acronym for sound navigation ranging; asdic is an acronym for anti-submarine detection investigation committee.
    Synonyms: echo sounder, asdic


Sonar (originally an acronym for SOund Navigation And 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. Two types of technology share the name "sonar": passive sonar is essentially listening for the sound made by vessels; active sonar is emitting pulses of sounds and listening for echoes. Sonar may be used as a means of acoustic location and of measurement of the echo characteristics of "targets" in the water. Acoustic location in air was used before the introduction of radar. Sonar may also be used in air for robot navigation, and SODAR (an upward looking in-air sonar) is used for atmospheric investigations. The term sonar is also used for the equipment used to generate and receive the sound. The acoustic frequencies used in sonar systems vary from very low (infrasonic) to extremely high (ultrasonic). The study of underwater sound is known as underwater acoustics or hydroacoustics.

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Some articles on sonar:

Marine Mammals And Sonar
... Active sonar, the transmission equipment used on some ships to assist with navigation, has been suggested to be detrimental to the health and livelihood of some marine animals, although the ... It is conjectured that active sonar transmitters could confuse these animals and interfere with basic biological functions such as feeding and mating ... Although whales were originally thought to be immune to this disease, sonar has been implicated in causing behavioral changes that can lead to decompression sickness ...
SONAR (Symantec) - How It Works
... The main use of SONAR is to enhance detection of zero day threats ... Symantec claims SONAR can also prevent attackers from leveraging unpatched software vulnerabilities ... Ed Kim, director of product management at Symantec, expressed confidence in SONAR, "We've done extensive testing on emerging threats, and it catches early threats and variants of existing threats." ...
Mega Shark Versus Giant Octopus - Cast
... Sanders Dean Kreyling - US Sub Captain Stephen Blackehart - US Sub Sonar Chief Douglas N ... Hachiya - Japanese Sonar Tech Stanley Woo - Dick Ritchie Jay Beyers - Pilot Officer Stefanie Gernhauser - Sub Cmdr ... Destoyer Sonar Tech Dustin Harnish - U.S ...
Cyber Snipa - Products - SONAR Headsets
... Cyber Snipa range was expanded to include two types of gaming headsets the Sonar 2.0 and Sonar 5.1 ... The Sonar 5.1 headset in particular has received positive reviews from the online gaming community ...