echo sounder

名词 echo sounder:

1. a measuring instrument that sends out an acoustic pulse in water and measures distances in terms of the time for the echo of the pulse to return
   同义词：sonar, asdic

1. A device used underwater to produce pulses of sound, as for an echo sounder.
   声脉冲发送器置于水下产生声脉冲的装置，如回音器中的装置