- Short 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.
WHY NOT USE RADAR?
- 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.