- What motion sensors are?
There are several types of motion detectors:
-Passive infrared (PIR): They detect person's skin temperature through emitted black body radiation at mid-infrared wavelengths in contrast to the surrounding objects.
-Microwave: Similar to radar speed gun (an emission of a continuous wave of microwave radiation).
-Ultrasonic: An ultrasonic wave (sound at a frequency higher than a human can hear) is emitted and reflections from nearby objects are received.
-Tomographic motion detector:They sense disturbances to radio waves as they pass from node to node of a mesh network.
-Video camera software: Digital cameras.
- What sound detectors are?