How Sensors Sense Occupancy Sensors use either acoustic, passive infrared, ultrasonic, or a combination of two technologies to detect occupancy. Acoustic sensors use non-recording microphones that pick up sounds within a room. The sensor detects sounds in the voice frequency range. Pairs with infrared. Infrared sensing relies on moving body heat.
Ultrasonic sensors fill the room with high-frequency sound.
Movement causes the reflected sound to have a frequency shift. Lights are ON when they should be and OFF when the room is empty. All rights reserved.