ultrasonic transmitter

ultrasonic transmitter

[¦əl·trə′sän·ik tranz′mid·ər] (engineering acoustics) A device used to track seals, fish, and other aquatic animals: the device is fastened to the outside of the animal or fed to it, and has a loudspeaker which is made to vibrate at an ultrasonic frequency, propagating ultrasonic waves through the water to a special microphone or hydrophone.