Combined motion sensors

 

— combined (PIR + microwave) sensors consist of two types of sensors, infrared (PIR) sensor and microwave (microwave). The principle of operation of such sensors is that in addition to thermal analysis, the sensor emits electromagnetic waves with a high frequency, usually 5.8 GHz (may differ, depending on the manufacturer). Electromagnetic waves are bounced off the surrounding objects and thus the sensor can register even slight changes. Such sensors have fewer false positives, and they are more used outdoors, as they do not depend on the environment. Accordingly, this manifests itself in their value. Also, microwave waves can detect movement outside the desired zone, for example, outside the window.