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Motion Sensors are a critical part of a quality burglar alarm system.
The term motion detector is a misnomer, they do not sense motion. In fact, in the industrial machine industry there are motion detectors. The original motion detectors were crude devices with a spring loaded, balanced arm which if disturbed would rock and complete a circuit setting off the alarm, later they where a ball bearing in a cube which if tilted would complete a circuit (also known as tilt switches. Today high end applications use polar magnetism to sense changes in the field, thus position. (This is a rudimentary explanation of a complex subject.)
“Motion Detectors” currently used by IPS today actually sense changes in the target environment:
- PIR (Passive InfraRed) the most common
- Sense Heat often in the range of 7% change in ambient room temperature
- These units are prone to false alarms due to heater vents suddenly blowing hot air into the target area, sunlight reflected off of a car windshield through a window into the sensor and more.
- Ultrasonic (Sound Wave) rare now (very popular 20 years ago)
- Senses the change in echo back in a controlled target range (like sonar)
- Sensor sends out pulses and measures the reflection timing off a moving object.
- These units are highly sensitive to changes in barometric pressure (humidity)
- Microwave are commonly used in outdoor installations
- Sensor sends out microwave pulses and measures the reflection timing off a moving object
- These units are useful but prone to falsing due to their single sensor
- Dual Tech (Dual Technology) more reliable popular option
- The unit utilizes two different sensor arrays
- PIR (Passive InfraRed)
- Microwave
- Pet Immune Dual Tech - Ignores up to a 100 pound pet
- Utilizes multiple detection arrays combined with a complex algorithm that discriminates reasonably reliably the difference between things and people moving
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