THE DEVICE HAS FIVE MAIN FUNCTIONAL PARTS: OSCILLATOR, TRANSMITTER, RECEIVER, DEMODULATOR, AND AUDIO OUTPUT. THE OSCILLATOR GENERATES THE 70 KHz PRIMARY FREQUENCY. THE TRANSMITTERS (THE TWO IONOVAC TRANSDUCERS) SENDS OUT THE ULTRASONIC BEAM. THE RECEIVER (IN THE BLACK BOX) PICKS UP REFLECTIONS AND THE DEMODULATOR CONVERTS THEM TO AUDIBLE FREQUENCIES WHICH ARE THEN PLAYED BACK THROUGH THE AUDIO OUTPUT.