Electronics Engineering
Electrical Engineering

What is a sonar transducer?

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Wiki User
2008-06-11 03:43:34

A sonar transducer is the element in the sonar apparatus that

turns the electrical signal into sound, which is mechanical energy,

and then does the opposite for returning signals. A generator of

some kind creates and amplifies the electrical signal, it is

directed to the transducer, which then makes the conversion, and

the pulse is sent out. The transducer then "listens" for returning

energy, and converts anything that comes back into an electrical

signal which is sent to the receiver. Sonar is (briefly) the use of

sound (which is mechanical energy) to "look at stuff" in in water

or other media. An electrical signal is generated by the equipment,

and it is changed into mechanical energy by a special crystal in

the same way a speaker changes electrical energy into sound we

hear. The transducer is a piezoelectric crystal that works

on the principle of the same name. Let's look at a transducer and

see how it works, but first let's see what the underlying physics

says about it. Piezoelectric crystals are crystals that change

shape when we apply a voltage across the crystal. Depending on the

placement of the leads that apply the voltage and the orientation

of the crystal, it will expand or contract to a DC voltage. If we

reverse the polarity of the applied voltage, the crystal will

contract or expand (respectively) in just the opposite way.

Applying an AC voltage causes the crystal to respond in that same

way, and it will vibrate. These vibrations travel through the water

or other media we are applying it to. The sonar transducer is a

crystal mounted in a "holder" or some kind. It has electrical leads

attached. The whole of this is "packaged" appropriately depending

on whether it is going to be mounted on the hull of a vessel or

held in the hand by an operator. A link is provided to a group of

pictures of different types of transducers posted at photobucket.

Surf on over and have a look.

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