A motion sensor uses one or more multiple technologies to detect movement in an area. If a sensor is tripped, a signal is sent to the security system’s control panel and to the monitoring center which will alert of a potential threat at home. There are different types of motion sensors. First, there is the passive infrared which detects body heat or uses infrared energy. Other types send out microwave pulses and measure the reflection of a moving object. They cover a larger area than infrared sensors, but they are vulnerable to electrical interference and may be more expensive. There are other types of sensors which uses a combination of infrared and microwave energy.