The voltage monitoring circuit includes a first multiplexer, a controller, a resistor-network circuit and a first comparison circuit. The first multiplexer receives a plurality of first subject voltages. The controller controls the first multiplexer to output one of the plurality of first subject voltages and generates a testing signal including a plurality of electric potentials. The controller is configured to output the plurality of electric potentials switching according to a switch command. The resistor-network circuit is configured to sequentially generate a plurality of first reference voltages according to switches of the plurality of potentials. The first comparison circuit is configured to sequentially compare each of the plurality of first reference voltages to the first subject voltage for sequentially outputting a plurality of first comparing results and sending the plurality of first comparing results to the controller so that a voltage value of the first subject voltage is determined.

Power cabling connections for supplying power from a power supply to a plurality of remote radio heads include a trunk power cable having a trunk power supply conductor and a trunk return conductor that are enclosed within a cable jacket and electrically insulated from each other; and a plurality of remotely-controlled switches that are interposed between the trunk power cable and the respective remote radio heads that are configured to selectively electrically connect the trunk power supply conductor and the trunk return conductor to a respective one of the radio heads.

A system and a method for distributing power to telecommunication subscriber lines is disclosed. It is important that the power dissipation in the subscriber line interface circuits, SLICs is reduced. Power dissipation occurs when the subscriber lines are fed with a voltage level that is higher than necessary. It is also important that the implementation allows for flexibility when configuring the subscriber lines. These problem have been solved by using a power distribution system comprising at least three power supply units with different power supply voltages, a control unit and a switching unit connected between the SLICs and the power supply units. The control unit is adapted to determine the loop voltages of the subscriber lines and to connect the corresponding SLIC to the power supply unit giving the least power dissipation.

Power cabling connections for supplying power from a power supply to a plurality of remote radio heads include a trunk power cable having a trunk power supply conductor and a trunk return conductor that are enclosed within a cable jacket and electrically insulated from each other; and a plurality of remotely-controlled switches that are interposed between the trunk power cable and the respective remote radio heads that are configured to selectively electrically connect the trunk power supply conductor and the trunk return conductor to a respective one of the radio heads.