First, the principle of passive infrared detector
In nature, any object above absolute temperature (-273 degrees Celsius) will produce an infrared spectrum. In the passive infrared alert area, when no object moves, the pyroelectric infrared sensor senses only the background temperature when moving the object. Entering the alert area, through the Fresnel lens, the pyroelectric infrared sensor senses the difference between the temperature of the moving object and the background temperature, and converts the change of the infrared signal into an alarm signal that is sent after the electrical signal. Passive infrared detectors do not emit infrared spectrum itself.
Second, false alarm caused by equipment failure
1, damage failure. Including all performance failures and sudden failures. Such failures are usually caused by the damage of components or poor production processes (such as cold welding, false welding, etc.).
2, drift failure. It refers to the failure caused by excessive drift of the parameters of the components and the power supply voltage. For example, too high a temperature will cause a change in the resistance value of the resistor.
Third, the environmental change caused by false alarm
1. Inadequate equipment installation often causes false alarms;
2. Facing alarm caused by temperature changes of air conditioning and ventilation fans;
3. The door or window of the prevention area is not closed, and false alarms are caused by people or animals.
4. When the temperature difference between indoor and outdoor is large, the wind blows the curtain to cause false alarm;
5. Multiple detectors transmit signals at the same time, which may result in missing reports or interferences (wireless only);
6, the alarm system code error caused by other wireless infrared detector false alarm. When the device performance is good or bad (only wireless type).
Fourth, the solution
1. Install the infrared detector according to the installation requirements of the manual;
2. Avoid areas where the temperature difference and air convection are strong;
3. The doors and windows of the prevention area are closed and the detector is normally opened;
4, the doors and windows closed or tied curtains;
5, to reduce the scope of cross-detection in the prevention area, to avoid the simultaneous launch of the alarm signal;
6, fast and accurate code, to prevent mis-recording information.
Fifth, low false alarm protection
1, "0" falsely misleading products. It is believed that there are no absolute "0" false alarm products for products that use PIR as a detection sensor. Only the constant technological optimization can reduce the frequency and frequency of false alarms. The reason is that the infrared detector only judges the specific environment and certain conditions according to the program preset in the detector microprocessor. The sensitivity of detection is changed by changes in the environment and conditions. Controlling the change in the environment is the key to reducing false alarms.
2, CCC certification. Qualified products CCC mandatory certification is a must, but also select high-quality electronic components, strict quality system maintenance, trusted quality commitment and perfect after-sales service.
3, multi-technology combination to improve the reliability of the detector, the current products are: passive infrared detectors, microwave + passive infrared double Kam detector, voice + vibration glass broken double Kam detector, ultrasonic + passive infrared double Kam detector Wait.
4, special circumstances. Some environmental noise detectors can't do anything. For example, mice come out in the defense area; pets move around indoors. For this reason, scientific and technological personnel have introduced the micro-processing technology into the alarm system so that they have a certain ability of discrimination and logic discrimination, and can judge to some extent whether it is an intruder or an alarm caused by environmental noise.
In nature, any object above absolute temperature (-273 degrees Celsius) will produce an infrared spectrum. In the passive infrared alert area, when no object moves, the pyroelectric infrared sensor senses only the background temperature when moving the object. Entering the alert area, through the Fresnel lens, the pyroelectric infrared sensor senses the difference between the temperature of the moving object and the background temperature, and converts the change of the infrared signal into an alarm signal that is sent after the electrical signal. Passive infrared detectors do not emit infrared spectrum itself.
Second, false alarm caused by equipment failure
1, damage failure. Including all performance failures and sudden failures. Such failures are usually caused by the damage of components or poor production processes (such as cold welding, false welding, etc.).
2, drift failure. It refers to the failure caused by excessive drift of the parameters of the components and the power supply voltage. For example, too high a temperature will cause a change in the resistance value of the resistor.
Third, the environmental change caused by false alarm
1. Inadequate equipment installation often causes false alarms;
2. Facing alarm caused by temperature changes of air conditioning and ventilation fans;
3. The door or window of the prevention area is not closed, and false alarms are caused by people or animals.
4. When the temperature difference between indoor and outdoor is large, the wind blows the curtain to cause false alarm;
5. Multiple detectors transmit signals at the same time, which may result in missing reports or interferences (wireless only);
6, the alarm system code error caused by other wireless infrared detector false alarm. When the device performance is good or bad (only wireless type).
Fourth, the solution
1. Install the infrared detector according to the installation requirements of the manual;
2. Avoid areas where the temperature difference and air convection are strong;
3. The doors and windows of the prevention area are closed and the detector is normally opened;
4, the doors and windows closed or tied curtains;
5, to reduce the scope of cross-detection in the prevention area, to avoid the simultaneous launch of the alarm signal;
6, fast and accurate code, to prevent mis-recording information.
Fifth, low false alarm protection
1, "0" falsely misleading products. It is believed that there are no absolute "0" false alarm products for products that use PIR as a detection sensor. Only the constant technological optimization can reduce the frequency and frequency of false alarms. The reason is that the infrared detector only judges the specific environment and certain conditions according to the program preset in the detector microprocessor. The sensitivity of detection is changed by changes in the environment and conditions. Controlling the change in the environment is the key to reducing false alarms.
2, CCC certification. Qualified products CCC mandatory certification is a must, but also select high-quality electronic components, strict quality system maintenance, trusted quality commitment and perfect after-sales service.
3, multi-technology combination to improve the reliability of the detector, the current products are: passive infrared detectors, microwave + passive infrared double Kam detector, voice + vibration glass broken double Kam detector, ultrasonic + passive infrared double Kam detector Wait.
4, special circumstances. Some environmental noise detectors can't do anything. For example, mice come out in the defense area; pets move around indoors. For this reason, scientific and technological personnel have introduced the micro-processing technology into the alarm system so that they have a certain ability of discrimination and logic discrimination, and can judge to some extent whether it is an intruder or an alarm caused by environmental noise.
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