| 摘要 |
<p>The invention concerns a local combined telephone and an alarm system comprising a central base communicating through two-way radio channel, according to a multiple access communication protocol, with telephone stations and detectors adapted to detect an emergency situation. The base transmits at regular intervals of less than 10 minutes, scanning messages addressed to the detectors and determines whether the detectors are operating, depending on whether it receives clearance messages from the detectors.</p> |
