A small radio transmitter that connects to the control panel of your security system. In the event that your phone line fails or is cut the cellular radio contacts the central station.
Microphone and vibration sensors listen for the specific frequency of sound that glass makes when it breaks. To reduce false alarms it also listens for the vibration of the impact that caused the glass to break.
Motion Sensors detect motion by infrared, microwave, or both. Newer units analyze motion to determine if the threat is valid.
The keypad is the means of communication between the user and the control panel. It the way the alarm is armed and disarmed, and provides important system information.
Control Panel The brains of the security system, the panel is hidden, backed up by battery, and wired to provide line seizure.