| 摘要 |
PROBLEM TO BE SOLVED: To build up a CATV system that can continue provision of service to each subscriber's home even when a head end receives no radio wave. SOLUTION: CATV centers 10-40 of CATV systems 1-4 adjacent to each other are interconnected by optical fibers 81-95. For example, changeover switches 51a-51f of a line changeover device 50 in the 1st CATV system 1 are usually thrown to the positions shown in Figure and terminals make two- way communication with the head end 12. When the head end 12 cannot receive a radio wave, the line changeover device 50 detects loss of the radio wave to throw the changeover switches 51a-51f to the other positions so as to allow the terminals to continuously make 2-way communication with a head end of other adjacent CATV system. Thus, the CATV system 1 can continue the provision of service to subscribers, and should all of the head ends 12, 22, 33 lose the radio wave, the CATV systems 1-3 can receive an outgoing signal from a facility 40 against radio wave disturbance.
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