| 摘要 |
PURPOSE:To decrease the deterioration of characteristic of a metering pulse by turning on/off talking current with logical switch control to decrease application time of specific noise generated attended with a minute current of a non-feeding talking current supply circuit. CONSTITUTION:The normal feeding and the reverse feeding are changed over by applying a control voltage to terminals N, R in a metering pulse transmission circuit comprising a normal feeding current supply circuit Bn giving a battery level to a subscriber line A and ground level to a subscriber line B, a reverse feeding current circuit Br supplying a current of opposite polarity, a normal filter circuit Cdcn, a reverse filter circuit Cdcr and a logical circuit Nrc, the time when both the current supply circuits are activated is decreased by signals Bfn, Bfr and the deterioration of characteristic due to application of specific noise generated together with a minute current of non-supply side onto the feeding side is reduced. |
