Cable television communication system with passive sensor signal path and a subscriber power supply source

摘要

A cable television system includes security means. A security sensor is provided a subscriber's house and when it generates an emergency signal a transmission path is formed by non-active elements from the security sensor to a trunk cable. An external control unit has a checking function of a power supplying state to the security sensor. The external control unit can communicate with a central station with respect to power source conditions of subscribers.