| 摘要 |
PURPOSE:To remove a time measuring error due to the variation in a pulse signal wave by increasing the rising ratio of an envelope, by reducing the amplifying gain of the pulse signal wave from the point of time when the transmitted pulse signal wave reached a set reference level. CONSTITUTION:When a transmission order signal Tc is inputted, a 'H' signal A is outputted from a trigger circuit 2 up to the point of time when the arrival of a pulse signal wave R is estimated and, next, a signal B is outputted from a gate circuit 3 at the falling of the signal A to set FF10 and a signal C is outputted. By this mechanism, an integration circuit 11 is operated and voltage VD rising with the elapse of a time is outputted and drop voltage VE is outputted corresponding thereto from a subtraction circuit 12 and the gain of an amplifying circuit 6 gradually increases while voltage comparators 7, 9 are operated by the signal B. Next, when the voltage VR of the amplified signal wave R becomes larger than voltage VS, a signal ZCS is outputted and, when VR<VS is formed, FF10 is reset by a signal ZC. Voltage VE rises as voltage VD drops and amplifying gain is reduced. |
