| 摘要 |
PURPOSE:To enable the responding to the modification state large in the fluctuation signal in a current meter for correlation processing of detection outputs on the upstream and downstream sides, by comparing an input voltage corresponding to the detection signal with a reference voltage to control the voltage division ratio of a voltage divider for detection signals and the reference voltage. CONSTITUTION:A fluid movement detection signal 1a with an upstream side detector 1 is turned to a fluctuation signal U1 with an amplifier 3 or the like and supplied to a multiplier 7 for correlation processing via a delay circuit 5 such as CCD. An input voltage Pa corresponding to the signal U1 is compared with a reference voltage corresponding to an upper limit allowable voltage or the like of the circuit 7 by a comparator 14. Then, when it exceeds the reference voltage, the output of the comparator 14 is inverted to change over the voltage division ratio of a voltage divider 11 while with the inverted output of the comparator 14, the reference voltage gives the lower limit allowable voltage of the multiplier 7. Thus, the fluctuation signal to the circuit 7 will be held in an allowable range in the voltage. The same can be done on the downstream side and this enables the responding of the modification state large in the fluctuation signal thereby preventing possible erroneous measurement. |
