| 摘要 |
An ultrasonic flowmeter includes first and second ultrasonic transducers which are mounted along a fluid measuring section opposite each other and whose connecting line makes an angle different from 90 DEG with the axis of the fluid measuring section. The transducers can be switched to transmit mode or receive mode by a switching arrangement having first and second switching paths per transducer, one conducting and the other simultaneously nonconducting, or vice versa. One end of the first and second switching paths is coupled to the associated first or second transducer. The first switching paths associated with the first and second transducers having their other ends coupled to the input of a measuring circuit, and the second switching paths associated with said first and second transducers having their other ends coupled to an oscillator. To reduce crosstalk, the switching arrangement includes two constantly nonconducting, parallel-connected switching paths coupled in series with an inverting amplifier between the oscillator output and the input of the measuring circuit or between the inputs of the two transducers.
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