Passive Ultrasonic or Infrasonic A motion detection device that “listens” for ultrasonic sound energy in an area, and reacts to high frequencies associated with intrusion attempts. The sensor “listens” for frequencies that have a range between...
Microwave Sensors Motion detection devices that flood a designated exterior or interior area with an electronic field. A movement in the area disturbs the field and sets off an alarm. Signals generated are within pre-set limits that do not affect humans or the...
Active Ultrasonic A motion detecting device that emits ultrasonic sound energy into a monitored area and reacts to a change in the reflected energy pattern Ultrasonic sound is transmitted from the device in the form of energy The sound uses air as its medium and...
Cord Trap An outdated means of detection consisting of a cord or wire stretched across a doorway and connected to the protective circuit Breaking or pulling the cord loose breaks the circuit and trips the alarm Space-protection devices and photoelectric beams have...
Lacing Fine wire stretched back and forth across skylights, ducts, or other openings. An intruder breaking a wire will trip the alarm. Most modem alarm systems use motion detectors instead of...