| 摘要 |
PURPOSE:To handle two or more kinds of ultrasonic vibrators by simple and inexpensive constitution, by converting the receiving signals by two or more kinds of the ultrasonic vibrators to high frequency bands almost equal in center frequency before converting the same to low frequency bands. CONSTITUTION:Relays 3, 5 are controlled by a control signal 7, and the receiving signals 1-1-1-3 from ultrasonic vibrators different in a frequency characteristic and carrier signal generating circuits 4-1-4-3 are selected corresponding to each other to convert the output of a mixer 6 to the same high band. The output of the mixer 6 is supplied to a mixer 11 through a band-pass filter 8 to be converted to a low frequency band by the carrier signal from a carrier signal generating circuit 10. The output of the mixer 11 is outputted through a low-pass filter 12. |
