Depending upon the application, an alarm output may be local or remote but typically they’re a combination of the two.
Local alarms do not include monitoring, though may include indoor and/or outdoor sounders (e.g. motorized bell or electronic siren) and lights (strobe or rotating) which may be useful for signaling an evacuation notice for people during fire alarms, or where one hopes to scare off an amateur burglar quickly.
Alarm systems utilize a digital telephone dialer unit that dials a central station via an available phone line to initiate an alarm, with an encoded message string that the central station decodes.
These may connect to the regular phone system on the system side of the demarcation point, but typically connect on the customer side ahead of all phones within the monitored premises so that the alarm system can seize the line by cutting-off any active calls and call the monitoring company if necessary.
Alarm systems can be programmed to indicate which specific sensor was triggered, and monitors can show the physical location (or “zone”) of the sensor on a list, which can make the resulting response more effective. For example, a water-flow alarm, coupled with a flame detector in the same area is a more reliable indication of an actual fire than just one sensor reporting alone.
Many alarm panels are equipped with a backup dialer capability for use when the primary phone line is out of commission.
The redundant dialer may be connected to a second phone line, or a specially encoded cellular phone, radio, or internet interface which bypasses the phone line entirely. sometimes necessary to thwart intentional tampering with the phone line(s).
Even detected tampering with the line could trigger a supervisory alarm via the radio network, giving early warning of an imminent problem in the case of arson, for instance.
In some cases a remote building may not have phone service, and the cost of trenching and running a direct phone line may be prohibitive, a wireless cellular or radio device, as the primary communication method provides a cost effective solution. Commonly used forms of backup communication that we use at C&B Alarms Ltd. are:
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