NoSuchPerson Stop, or I'll ask you again!
| | Re: Alarms <Reply # 10 on 3/10/2009 2:31 AM >
| | | Alarm lines aren't like regular phone lines. They're called alarm loops, dry loops or DVACS lines. Basically, they're a constant data-like connection between a modem in the alarm panel and the monitoring center. They're dedicated and fairly pricy. This applies to commercial installations. Residential alarms, for the most part, work differently. Most work on a dial-out method, whereby once an alarm is detected, it dials out to a monitoring center's modem to transmit the alarm signal. Some (ADT does this) will seize the line, disconnecting any telephone sets in the house and keeps a constant connection between the alarm panel and the monitoring center once it goes into alarm. This allows the operator to interrogate the system very quickly as well as provide 2-way voice should the customer have such a feature. In either case, as DW said, they can often include cellular backup. So even if one were to chop the telco lines, it wouldn't matter but these types of systems are really uncommon except in something such as a bank or other large outfit as they're anything but inexpensive. It's generally safe to say that in any decent installation, cutting the phone lines WILL signal some sort of alarm. It's just a question of whether that signal will elicit a response from a guard/police. In terms of AC power - it all depends. There's one type of system I know of that is powered in several ways. Firstly, the regular 120V mains supply. Then it uses power provided on a regular telco line, then the power supplied on a DVACS line, and lastly with a built in battery. The loss of any of these supplies will signal an alarm to the monitoring station, and any one of the supplies is sufficient to at least signal an alarm (the power provided over a copper voice line and a DVACS isn't enough to power the entire system, but it's enough to send an "oh shit" message). The easiest way? Look at the panel itself. No lights = no alarm. Of course, by this point, you're already SOL if it's active... [last edit 3/10/2009 2:33 AM by NoSuchPerson - edited 1 times]
Unit calling radio say again? |
|