Motion detectors use which technologies?

Motion detectors use which technologies?

• A. Passive Infrared and/or Microwave Technology
• B. Photoelectric Beams
• C. Video Analytics
• D. Ultrasonic

Answer: (A)

Motion detectors in security systems mainly sense movement by detecting energy changes in the room. The most common technologies are Passive Infrared sensors, which detect heat emitted by people, and microwave sensors, which emit energy and monitor changes in the reflected signal. When a person moves, the heat pattern changes for the PIR sensor, and the reflected microwaves show a Doppler shift that indicates motion. Many detectors use these two technologies together in a dual-technology setup to reduce false alarms, since it’s unlikely for both sensing methods to be triggered by a single non- threat event. Other options describe different sensing methods: photoelectric beams are break-the-beam sensors used for perimeter protection, not typical room motion detection; video analytics relies on processing camera footage to detect movement rather than a stand-alone motion sensor; ultrasonic uses sound waves to detect motion, which is another approach but less common for standard interior motion detectors.

Motion detectors in security systems mainly sense movement by detecting energy changes in the room. The most common technologies are Passive Infrared sensors, which detect heat emitted by people, and microwave sensors, which emit energy and monitor changes in the reflected signal. When a person moves, the heat pattern changes for the PIR sensor, and the reflected microwaves show a Doppler shift that indicates motion. Many detectors use these two technologies together in a dual-technology setup to reduce false alarms, since it’s unlikely for both sensing methods to be triggered by a single non- threat event.

Other options describe different sensing methods: photoelectric beams are break-the-beam sensors used for perimeter protection, not typical room motion detection; video analytics relies on processing camera footage to detect movement rather than a stand-alone motion sensor; ultrasonic uses sound waves to detect motion, which is another approach but less common for standard interior motion detectors.