| 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 the reference voltage to control the amplication factor of a detection signal amplifier and the reference voltage. CONSTITUTION:A fuild movement detection signal 1a with an upstream side detector 1 is turned to a flustration signal U1 with an upstream amplifier 3 and supplied into a multiplication circuit 7 for correlation processing via a delay circuit 5 such as CCD. The 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 control change over the amplification factor of the amplifier 3 with the control of an amplification factor switch 11 while with the inverted output of the comparator 14, the reference voltage gives a lower limit allowable voltage of the multiplier 7. Thus, the fluctuation signal to the circuit 7 will be held within an allowable range in the voltage. The same can be done on the downstream side and thus, any modification state large in the fluctuation signal can be responded thereby preventing erroneous measurement. |
