| 摘要 |
<p>An alarm installation comprises a central alarm station (9) and a number of alarm units (1). The alarm units can send messages to the central alarm station (9) and the central alarm station (9) can send voice messages or recorded spoken messages to a number of alert units. All sending operations are performed on the public telephone network. The central alarm station (9) may have a receipt of played-off messages by means of some simple sending method as by operating the dialling table of a receiving telephone. The alarm units (1) contain at least one detector (29-35) for an emergency situation and will at the activation of such a detector directly or immediately send a message thereof to the central alarm station (9). The latter receives the message and will send a corresponding spoken message to the various alert places, unless another message telling that the alarm should be shut off has arrived from the alerting alarm unit (1) within a predetermined time after the reception of the first, immediately sent message.</p> |
