What activates your alarm system when you're not at home? Motion Sensors (PIR's - Passive Infrared) which are connected to your alarm control panel issue a signal and activate the alarm. The type of PIR's used in your home security system and the quality can be crucial.
This Home Security Online security detector is a 'single mode' PIR motion detector, which means it detects only on motion. It features passive infrared and microprocessor technology that covers a 12m range.