| 摘要 |
PURPOSE:To always output a real value Karman vortex pulse, by prohibiting the output of the Karman vortex pulse when the relation between the frequency and amplitude of the output of a Karman vortex flow rate sensor does not satisfy predetermined relation. CONSTITUTION:The output (a) of the analogue electric signal outputted from a Karman vortex flow rate sensor 2 is binarized by a voltage comparator 41 through the filter of a binarization circuit 4 to be converted to a Karman vortex pulse (b). The voltage comparator 41 has the predetermined histeresis width VH determined on the basis of the resistance shown by a resistor R1 and, when the amplitude of the input signal (d) thereof is below the histeresis width VH, the input signal (d) of the voltage comparator 41 is not pulsated. Therefore, if the frequency characteristic of the attenuation rate of the filter is determined so as to be proportional to the reciprocal of the amplitude of the output (a) of the sensor, a noise signal is removed without being pulsated. By this method, a real value Karman vortex pulse can be outputted. |
