| 摘要 |
When the alarm is activated a transmitter (14) with at least two communication channels (15) is used to contact a receiver. A monitoring unit (13) is provided for the communication channels and if any are faulty the alarm is sent out to the receiver via a second channel. An Independent claim is also included for an alarm process using this system. TECHNOLOGY FOCUS - IMAGING AND COMMUNICATION - The first channel is a PSTN telephone line and the second channel is a PSTN, GSM, NMT, radio communication or satellite communication line. The monitoring unit measures voltage and current in the channel. |
