• IMG_0050.JPGShort for SOund Navigation And Ranging.
  • Helpful for exploring and mapping the ocean.
  • Used to develop nautical charts and locate underwater hazards when navigating the sea floor.
  • Low frequency sonar has a massive range.
  • Dolphins and whales use sonar and can tell the difference between objects as small as BB pellets from 50 feet away.
  • Dolphins and whales use sonar more than sight to locate their food, families and directions


  • Transducers emit an acoustic signal into the water.
  • If an object is in it’s path it’ll bounce back as an echo to the transducer.
  • If tit is fitted with the ability to receive the signal i can measure the strength.
  • By working out the time between the emission and reception the transducer can determine the range and orientation of the object.


  • Normally used to detect noise from marine objects (ships and submarines) and from marine animals like whales.
  • Doesn’t emit its own signal, advantage for military vehicles that don’t want to be found out, or for scientific missions that concentrate on listening to the ocean.
  • Only detects sounds waves coming toward it
  • Cant measure the range of an object unless it is used together with other listening devices
  • Multiple passive sonar devices can be used to try to triangulate a signal.


  • Radio waves travel faster than sonar so why isn’t this used instead?
  • The simplest reason is because Radio waves use a microwave frequency range (approx 1cm wavelength) the microwaves are strongly absorbed by the water within feet of emission.

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