System composition and working principle of active detector:

Active infrared detector is composed of transmitter and receiver. The transmitter is composed of power supply, light source and optical system. The receiver is composed of optical system, photoelectric sensor, amplifier, signal processor and other parts. Active infrared detectors need a transmitter to generate the light source. Objects obstruct the receiver and cannot receive enough light sources. It is considered that there are objects or objects passing through. Generally used outdoors, the protection distance is long, and the detection distance can reach more than ten times that of passive infrared.

The passive infrared detector judges whether someone is moving according to the change of the external infrared energy. It uses the human body (up to 37 degrees left hundred hours of infrared) as the light source. The infrared energy of the human body is different from the environment. In the area, the position of the different infrared energy collected by the detector changes, and then the alarm is issued through analysis. It is generally used indoors and is easily interfered.

Advantages and disadvantages of passive infrared sounder

Advantages: it does not emit any type of radiation, the power consumption of the device is small, the concealment is good, and the price is low.

Disadvantages: easy to be interfered by various heat sources and sunlight sources; passive infrared penetration is poor, the infrared radiation of the human body is easily blocked, and it is not easy to be received by the detector; easy to be interfered by radio frequency radiation; when the ambient temperature and the human body temperature are close, the detection and Sensitivity drops significantly, sometimes causing short-term failure.