An alarm system can be described as a whole of devices capable of detecting intrusions in protected rooms, communicating this to the control unit so that this latter can carry out a local remedy and/or transmit the alarm at a distance.
Each alarm system will be activated at the moment it is installed; the system can be armed or disarmed completely or partially with commanding devices, but the tampering protection of all single components of the system will always keep working, as well as the control of the system’s functions and batteries (supervision).

A quality alarm system is realized by providing for all dangerous events, and with installation of appropriate detectors in such way that each event is signalled the quickest possible.
The control unit has to check all detectors and needs to have adequate instruments for an efficient reaction depending on the event; sirens and flashers to dissuade, phone diallers for emergency calls, etc.