| 摘要 |
<p>PURPOSE:To facilitate decision to discriminate whether a fault is the fault of a transmission line or the fault in a subscriber's house when the fault occurs by providing a power supply state detector which detects the power supply state of a device in the subscriber's house and controls a line switching device. CONSTITUTION:In case of where the power supply connected to the power supply state detector 16 at a spot B is in a cut-off state, the power supply state detector 16 detects the cut-off state, and outputs a loop-back control signal to the channel switching device 14. The channel switching device 14 having received the loop-back control signal returns a picture encoded signal sent from a high efficiency encoding device transmitting part 2 at the spot A through the line switching device 13 to a high efficiency encoding device receiving part 3 through the channel switching device 13 at the spot A. As the result, a picture transmitted from a video camera 4 at the spot A is reflected on a TV receiver 5 at the spot A. Thus, when the fault occurs, the decision to discriminate whether the fault is the fault of the transmission line or the fault in the subscriber's house can be easily executed.</p> |
