What are they?
Motion detectors spot the movement in areas covered by the security sensors. Motion detectors transmit high frequency radio wave signals. They give a warning that someone is entering into your home.
Different kinds of motion detectors & how they work:
Infrared Sensors:
Motion detectors use infrared light to detect heat changes, i.e. when a person moves across this light it detects them with the help of the infrared sensors. If a person moves in the range of the motion sensors, the alarm is activated. Infrared sensors are cheaper than microwave sensors and ultrasonic sensors. Infrared sensors are generally smaller and very reliable.
Vibration Sensors:
It detects a person through vibration. Many car alarms have this feature to alert the owner that something has bumped into their car.
Photoelectric Sensors:
Some motion detection systems use lasers and photoelectric beams. The laser is shot across to the other side of the room or doorway. If the laser is interrupted the unit's alarm signal is activated.
Ultrasonic sensors :
They use a frequency around 30kHz. The transmitter bounces the waves of walls, furniture, windows and ceilings and when the room has stabilized, the alarm is armed.
Acoustic Sensors:
They can detect the energy produced by any kind of sound, including breaking glass. In the case of breaking glass from window intrusions, the pattern of the sound emitted is detected.
