#sonar__echo_sounder__asdic  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 (sonar is SOund NAvigation Ranging; asdic is Anti-Submarine Detection Investigation Committee)
  supertype:  measuring_instrument  navigational_instrument
  part of:  pigboat
  part:  pinger  a pulse generator used for echo sounding in sonar
  part:  pulse_generator__pulsegenerator  a generator of single or multiple voltage pulses; usually adjustable for pulse rate

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