The underwater heart of a sonar, built from piezoelectric ceramic elements that vibrate when driven and generate a voltage when an echo strikes them. Multibeams usually use separate transmit and receive arrays laid out at right angles (a Mills Cross), and the exact position and orientation of each array relative to the motion sensor must be surveyed into the vessel offsets. Fouling, paint and air bubbles on the face all degrade performance.
Divers say the transducer face has a beard of weed on it, no wonder the outer beams are noisy.
Also heard as
- sonar head
- head
- array
Related terms
MBES
Multibeam echo sounder: a sonar that measures a fan of depths across the track on every ping, covering a wide swath.
Wet end
The underwater parts of a survey system, such as the sonar head or towfish, as opposed to the topside electronics.
Lever arms
The measured distances between sensors on a survey vessel, used to carry positions and motion to each sonar.
Aeration
Air bubbles under the hull or across the transducer face that block sound and cause lost pings.
Pole mount
A sonar transducer fixed on a rigid pole over the side or bow of a boat instead of built into the hull.