Alarm tips

1. What is an anti-theft alarm system?
Anti-theft alarm system is a system that uses detectors of various functions to protect the surroundings, space, environment and people of the house.

2. What is a detector?
The detector uses sensors to sense the current, pulse and other signals generated by various physical and chemical changes to push the radio frequency circuit to emit an alarm signal.


3. Function and working mode of anti-theft host The host is the core of the system. It is used to receive the alarm signal from the detector and provide timely feedback; after receiving the alarm signal, the host will generate a high-decibel siren, and will dial out multiple sets of alarms set by the owner himself through the telecommunications network. phone.

4. Passive infrared anti-theft detector The passive infrared detector is based on * passive absorption of thermal energy. The infrared thermal energy emitted by the body when the animal is active is used for alarm. It is also called a pyroelectric infrared probe, and its detector does not emit infrared light.

5. The basic concept of infrared detection of passive infrared detectors Within the warning range, why can passive infrared detectors generate alarm signals when people move?
In nature, any object above absolute temperature (-273 degrees) will produce an infrared spectrum. The wavelength of infrared energy released by objects at different temperatures is different, so the infrared wavelength is related to the temperature.
There are two key components in the passive infrared detector, one is the pyroelectric infrared sensor (PIR), which can convert the infrared signal with a wavelength between 8 and 12um into an electrical signal, and can The white light signal has an inhibitory effect. Therefore, in the warning area of ​​the passive infrared detector, when no human body moves, the pyroelectric infrared sensor senses only the background temperature. When the human body enters the warning area, through the Fresnel lens, the heat The pyroelectric infrared sensor senses the difference between the temperature of the human body and the background temperature. Therefore, the basic concept of infrared detection of the infrared detector is to sense the temperature difference between the moving object and the background object. Another device is the Fresnel lens. The Fresnel lens has two forms, namely refractive and reflective. There are two effects of Fresnel lens: one is the focusing effect, which refracts (reflects) the infrared signal released by the pyrolysis on the PIR, and the second function is to divide the warning area into several bright and dark areas to make it enter the alert Moving objects in the zone can generate varying pyroelectric infrared signals on the PIR in the form of temperature changes, so that the PIR can generate varying electrical signals

6. What is the detection range?
The detection range refers to the induction range of the detector working normally, that is, the detector can detect the movement of all objects within this range to generate an alarm state.

7. What is the detection distance?
The longest distance that the detector can detect under normal operation.

8. What is the launch distance?
In the alarm system, the wireless device emits the wireless alarm signal in the form of electromagnetic waves at the longest distance after being triggered.

9. What is induction sensitivity?
Refers to the detection distance and the response speed when the detector is triggered to alarm, the induction sensitivity is high, it can be detected at a long distance from the detector, and the induction sensitivity is low, it can only detect a relatively short range.

10. Precautions for installation of passive infrared detectors Because passive infrared detectors belong to a weak signal detection device, attention must be paid to some details in the installation, such as height and sensitivity. To correctly install a passive infrared detector, you must master the following information: first, you must understand the performance characteristics of the detector, second, you must reasonably determine the installation location, and finally you must carefully debug. It can't be said that the detector can alarm to indicate that it is installed, so how to determine the installation position of a passive infrared detector?

* Determine the normal installation angle according to the instruction manual. The installation height is not arbitrary, which will affect the sensitivity of the detector and the effect of preventing pets. Imagine that a detector is installed at a height of 2M and a height of 2.5. When a moving object moves from the ground, the frequency of cutting the bright and dark areas is different.

* Do not face glass doors and windows. Passive infrared detectors are facing the glass.