What is Sonar and how does it help locate a black box?

  • 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. The term sonar is also used for the equipment used to generate and receive the sound.
  • Two types : 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. It may also be used in air for robot navigation, and SODAR (an upward looking in-air sonar) is used for atmospheric investigations. The acoustic frequencies used in sonar systems vary from very low (infrasonic) to extremely high (ultrasonic).