Controllers

If sensors act as the heart of an alarm system, controllers act as the brains. Controllers take information from the sensors and process this into a code that alerts the central monitoring station about what part of the monitored area is being intruded.

The control can connect to the central monitoring station in a few ways. Some high-end systems, such as those in government buildings and school campuses, use direct phone wires, or tamper-resistant fiber optic cable. More commonly in recent years, systems use a digital telephone dialer unit to dial the central station via the Public Switched Telephone Network (PSTN) and raise the alarm, either with a synthesized voice or increasingly via an encoded message string that the central station decodes. This call cuts off any other active calls from the premises and takes priority. Many systems are equipped with a backup dialer capability in case the primary PSTN circuit does not function.

Increasingly, voice over IP technology is being used to drive broadband signaling for alarm reporting. Older analog systems can be migrated to broadband with the addition of an alarm server device that converts telephone signaling signals or data port traffic to IP messages suitable for broadband transmission.