| 摘要 |
PROBLEM TO BE SOLVED: To provide an ultrasonic flowmeter capable of controlling properly the gain of an amplifier regardless of the quantity of impurities such as air bubbles or the like included in a fluid, executing flow measurement with a high S/N ratio even to the change of the kind or the temperature of the fluid, and executing stably always accurate flow measurement. SOLUTION: This flowmeter is constituted so that waveform data including at least a peak value in a received signal are digitally converted by an analog- digital converter 9 and preserved in a memory 11, and that a processor 10 selects the peak value in the case where the impurities such as the air bubbles, the solid powder or the like are not included in the fluid, as a selected peak value from among the peak values preserved in the memory at each prescribed time interval, compares the selected peak value with a peak set value set beforehand in the processor, transmits a control signal to a gain control terminal of the amplifier 5 based on the comparison result, and controls so that the peak value in an output signal of the amplifier becomes roughly in the same degree as the peak set value.
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