The optimum detector for passive detection is energy detector. Yet energy detector usually deteriorates due to fluctuation of background interference and a decrease in SNR.
Digital monitoring system has set aside alarm interface, it would be able to take the initiative to connect detector or passive emergency button, an increase of incidents of police video features.
数字监控系统预留有报警接口，将来可以连接主动探测器或被动式紧急按钮，增加对突发事件的报警录像功能。
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In the area of electronic security detectors, passive infrared detector is widely used because of their low cost, technical performance and stability of by users and professionals welcome.