| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide an ultrasonic detector in which an incorrect detection may not be caused when a sporadic ultrasonic noise is received or an ultrasonic signal transmitted from other ultrasonic transmitter is received. SOLUTION: The ultrasonic detector comprises a plurality of transmitters 3, 5 generating a burst signal of arbitrary pattern at an arbitrary frequency, an ultrasonic transmitter 10 transmitting a radiation ultrasonic signal 11 composed of a burst signal produced by adding a plurality of burst signals of arbitrary pattern outputted from a plurality of oscillators to a measured object 12, and a plurality of means 18, 19, 22, 23 for receiving an ultrasonic signal 13 reflected from the object and detecting the receiving burst signals of frequencies corresponding, respectively, to the transmission burst signals of a plurality of frequencies wherein the frequency and pattern of the transmitted burst signal are compared with those of the received burst signal, thus confirming reception of the reflected ultrasonic signal.</p> |
