A wireless motion detector alarm system consists of one or more detectors and a base unit.
The detector uses a PIR (Passive Infrared) detector to monitor heat changes in an area. Once a significant change in temperature is observed, the motion detector transmits a signal to the base unit.
The base unit receives the signal sent by the wireless motion detector and sounds an alarm. If the unit is being monitored by a service such as ADT or Brinks, the monitoring company will call the police and notify them that there is an intruder in your home.
Most wireless alarm systems are able to detect when doors or windows have been opened or there is a fire within the home. These additional features provide more complete security.
Motion detectors are only active when your alarm system is set in the "away" mode. This mode should only be used when your house is unoccupied. If you have pets, you can purchase pet immune detectors.