| 摘要 |
PURPOSE:To obtain real-value Karman vortex pulses which contain no noise by deciding whether or not there is a high-frequency noise component contained in a sensor output and switching constants of a low-pass filter for noise removal according to the decision result. CONSTITUTION:The low-pass filter 41 removes high-frequency noises from the sensor output of a Karman vortex flow rate sensor 2 and a 1st comparator 42 outputs Karman vortex pulses. A 2nd comparator 43 outputs Karman vortex pulses with the sensor output and a noise detector 44 compares the numbers of the Karman vortex pulses outputted by the 1st and 2nd comparators 42 and 43 with each other to decide whether or not there is a high frequency noise in the sensor output from the comparison result. The time constants of the low-pass filter 41 are changed according to the decision result.
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