Transducer Tips & Info Part 2

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How a Transducer Works.

OK, we now know the transducer converts electrical energy from the depth sounder into acoustic (sound) energy then back again. The depth sounder produces pulses of electrical energy that matches the characterics of the transducer. The most common frequencies used are 50kHz and 200kHz. Inside the transducer is a device called a piezoceramic disc that vibrates at the designed frequency. By measuring the elapsed time between transmitting the signal and receiving it back, the depth sounder is able to calculate the distance from the transducer to the object reflecting the signal. Just in case you were wondering how fast all this happens. Sound travels about four times faster in water that it does in air. While sound we can hear in the air is covering 768 miles per hour, in water it’s more like 3,320 mph.

The most basic type is called a single element transducer. That means it has one disc that vibrates at both 50kHz and 200 kHz. Higher performance transducers have multiple elements. On the higher end, transducers may have up to 15 individual elements. In these cases they would typically have one larger element for the 200kHz signal and 14 smaller elements working at 50kHz resulting in a much higher degree of sensitivity.

With regards to the transducer, it’s the combination of the amount of power transmitted, the size of the cone (beam angle), and the sensitivity of the transducer that determine how well any given sounder works. Next up we’ll go into “Beamwidth and Frequency of a Transducer.”