| 摘要 |
PURPOSE:To accurately display the reflected wave coming from underwater without generating a virtual image due to an auxiliary pole, by dividing a submerged detection range angle into plural sections and transmitting ultrasonic pulses having frequencies different at every section and forming a directional receiving beam at every frequency signal. CONSTITUTION:Ultrasonic signals having different frequencies are transmitted to the directions in a detection range and received. Therefore, the frequency signals corresponding to the detection range angles of phase shifters 4, 5, 6, 7 are detected to be separately subjected to phase shifting and the receiving signals of ultrasonic vibrators 101-108 are mixed with the signal mixture outputted from a signal mixture forming device 9 and a specific frequency signal is selected from said signal mixture. The phase shifters 4, 5, 6, 7 separately detect reflected waves returned from the detection range angle and outputs the same to a multiplexer 10 after similar phase shift control was performed by using the rectangular wave form guided from a phase shift controller 8. As a result, a directivity-receiving signal changing in a receiving direction within the detection range angle theta is outputted from a filter 12.
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