1. Activated by the control panel, it gives a loud audio signal to alert that an intrusion has occurred.

2. This is an audio detector, normally fixed onto the surface of a window, which ‘ linstens ’ for the specific sound patterns generated by breaking glass.

3. These are placed on all entry points, such as doors and windows. They consist of a magnet on the door/window and a contact switch on the frame. If the door / wind0w is opened the magnet moves away from the contact and sets off the alarm.

4. This is the brain of the system with a microprocessor and a keypad used to insert the code to activate or deactivate the alarm. It is linked to each zone of the building and can indicate where an intrusion has taken place and initiate automatic dialling of telephone numbers to give an alert.

5. This may be based on an infrared or photosensitive sensor and automatically switches on if it detects movement. It is often enough to deter a potential intruder from making any further attempt to break in.

6. This protects against attempts to break through walls, ceilings or floors. Based on the principle of resonance frequency, it can sense any abnormal vibration caused by hammering or drilling and trigger the alarm. It is usually effective up to about 3 metres.

7. This sense minute changes in infrared (heat) energy, caused by the movement of an intruder inside a room. If a person enters and moves within the detecting area, his body radiates more thermal energy than the surroundigs and activates the alarm.