| 摘要 |
PROBLEM TO BE SOLVED: To continuously use a circuit as is even in a service interruption state by supplying power to the circuit connection device of every subscriber after superimposing the power on a TV high frequency circuit that is connected to the circuit connection device from a tap-off. SOLUTION: A transmission line is connected to a node 12 from a head end 11 via an optical fiber, etc., and a power supply unit 13 is connected to the node 12 to supply the power to the node 12 and its subsequent equipments. The unit 13 superimposes the power of 60V on an existing coaxial cable and supplies the power to a trunk line branch amplifier 14, an extended amplifier 15 and a tap-off 16. The tap-off 16 contains a transformer 18 in parallel to a TV distributor 7. The power supplied from the unit 13 is dropped down to 30V from 60V by the transformer 18 and then supplied to every subscriber. In this case, an existing circuit is available as is since the voltage of 30V is superimposed on the leading wire connected to the subscriber from the tap-off. |
