| 摘要 |
PURPOSE:To realize the channel current supply system less in power loss, by selectively controlling the voltage of the DC supply current through the measurement of the line resistance of a subscriber and supplying channel current with the required minimum voltage. CONSTITUTION:When the telephone set 1 of the subscriber requested for the connection is determined, the central controller 18 closes the cross point switch 3 of the network 2 via switch driving unit 15 and connects and telephone set 1 with the line resistance measuring trunk 10. With this condition, the line resistance measuring trunk 10 measures the subscribing line resistor including the telephone set 1, converts the result into digital signal, and delivers it to the central controller 18 via the scanner 17. The central controller 18 selects the channel current supply trunk 11 or 12 with the resistance value read in. Thus, the power loss can be reduced by selecting optimum voltage. |
