DETECTOR FOR INCOMING AZIMUTH OF ULTRASONIC RECEIVING WAVE SIGNAL

PURPOSE:To receive satisfactorily the ultrasonic wave from a tow net, and to enable the measurement of the horizontal and vertical azimuths of the tow net from a towboat possible by combining the oscillators of plural ultrasonic wave receivers for forming a pair in a horizontal direction and controlling the directivities in the horizontal and vertical reception. CONSTITUTION:An ultrasonic wave receiver 1 installed on the bottom of a towboat 2 toward the direction of a tow net 4 is constituted of an ultrasonic wave receiver 3A wherein plural oscilltors 3A1-3An are installed at the intervals of the half wavelengths of the ultrasonic receiving signal and a wave receiver 3B wherein oscillators 3B1-3Bn are installed similarly to the receiver 3A and make a pair with the oscillators 3B1-3Bn. The wave receiving directivity is changed in desired horizontal and vertical directions by the combination of these oscillators 3A1-3An, 3B1-3Bn and the ultrasonic wave from the ultrasonic transmitter 5 of the net 4 is received with good directivity in the towboat 2 without being influenced by screw sound, etc., whereby the horizontal and vertical azimuths of the tow net are measured from the towboat.