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The Fresnel lens has two functions: one is focusing, that is, the pyro-infrared signal is refracted (reflected) on the PIR. The second function is to divide the detection area into several bright and dark areas so as to enter the detection area. The moving object can generate a varying pyroelectric infrared signal on the PIR as a temperature change.
What is Shuangjian technology?
According to the Doppler principle in physics, we know that microwaves are transmitted at a frequency, and when there are moving objects within their covered area, they will be reflected at another frequency, so that there is a frequency difference between the transmitted frequency and the reflected frequency. In this way, the size of the change can be detected and the speed of movement can be known. In combination with the infrared-detected signal, the internal CPU chip is used to calculate and process the two types of trigger signals, and the relevant characteristics of the signal are comprehensively analyzed to determine whether there is a visual area. Intruder. Double false detections have lower false positives. In addition, due to the comparison between the two models, the infrared detection can be adjusted to a higher sensitivity, thereby overcoming the near-body temperature effect, that is, when the room temperature is close to the human body temperature, the detector can still work normally.
What is Sanjian Technology?
Due to the influence of changes in the external environment on the detector, it may cause false alarms in the case of strong wind, sunlight, flying birds or other small animals, so the detectors are generally installed in the indoor environment. However, only when the intruder enters the room will the alarm be triggered, and the intruder will not be effectively blocked outside the door. Therefore, there is an urgent need for a detector on the market to be able to pre-alarm the intruder before it enters the room and put the line of defense outside the line. Moving, blocking the intruder outdoors, this is an outdoor detector. Due to the large number of factors affecting the outdoor environment, outdoor detectors have higher anti-false alarm capability than common detectors. Two or even three infrared sensors are used inside the detector. The double-window structure is used. When these sensors are judged to have a true human invasion, they will only alarm. The use of this technology can not only resist strong light (≥1 million Lux, but only tens of thousands of Lux for outdoor detectors), and it can resist the influence of strong wind, small animals, external noise and various adverse climates, and truly meet the requirements of outdoor protection. Claim.
What is a double curtain technology?
The direction-recognition curtain is generally composed of double curtains. The two curtains are divided into inner curtain A and outer curtain B. When the owner walks from inside to outside, first trigger the inner curtain A and then trigger the outer curtain B. At this time, the detector does not call the police; when the intruder enters from the outside, the outer curtain B is triggered first, and then the inner curtain is triggered. A. At this point, the detector immediately alarms. When the householder returns to the room after he goes out, he first triggers the outer curtain B to trigger the inner curtain A again. Therefore, it is necessary to distinguish between the return of the head of the household and the invasion of the outsider. The detector will delay the time of the alarm after the owner goes out to ensure the owner. No alarm when returning. Curtain detectors are generally used to prevent windows, balconies and other import and export areas, but after the installation of general curtain detectors, the owner may also trigger detector alarm in and out of the balcony, and the owner's activity space is greatly limited. Directional identification curtain detectors can solve this problem.
What is the four curtain technology?
The composition of the four curtains is the same as that of the double curtains described above, and it has the function of direction recognition. However, it adopts digital signal processing circuit (DSP) and applies a three-vector digital orthogonal analysis technology, which can more accurately identify the direction of movement of the human body and further improve the accuracy of the direction recognition.
What is the principle of passive infrared detectors?
The so-called passive infrared detector has only an infrared receiver. When a target is intruded and moves within a range, it will cause changes in the infrared radiation in the area, and the infrared detector can detect this change in infrared radiation and send an alarm signal. In fact, in addition to infrared radiation emitted by intruding objects, other objects within the detection range such as outdoor buildings, terrain, trees, mountains and indoor walls, desks, furniture, etc. will be radiated heat, but because these objects are not fixed Change, its thermal radiation is also stable, when the intruding object into the monitored area, the thermal radiation is destroyed, resulting in a change of thermal radiation, through the Fresnel lens, pyroelectric infrared sensor sensor It is the difference between the temperature of the moving object and the background temperature, and the alarm signal issued after the change of the infrared signal is converted into an electrical signal.
What is the principle of active infrared detectors?
The active infrared detector is composed of two parts: an infrared light emitter and a receiver. One end emits infrared rays and the other end receives infrared rays, and forms a loop through the infrared rays at both ends. The active infrared transmitter emits a modulated beam of infrared light that is directed at an infrared receiver to form a cordon. When the target intrudes into the cordon, the infrared beam is partially or completely blocked, and the receiver receives a signal to change and alarm.
Several operation modes and the principle mode of operation preferably circumferential <br> <br> infrared detector can be divided into: the power saving mode (12 seconds of continuous detection), the normal mode (10 seconds). Principle: After the infrared detector senses the moving human body, it immediately emits the first alarm signal. After the second alarm signal is automatically emitted after 10 seconds, the power saving mode: after the infrared detector detects the human body signal for the first time, it takes 12 seconds. If the human body signal is detected within the time, if it does not emit an alarm signal, the human body signal must be detected more than 12 seconds before the alarm signal is issued. This can greatly save power and reduce the false alarm rate.
When installing infrared detectors, what factors should be considered in the environment?
When the active infrared detector is used for indoor guarding, the working reliability is high. However, when used outdoors, it is affected by the environmental climate. Because the lens surface of the optical system is ** in the air, it is easily contaminated by dust and other debris. However, the cordon or alert net composed of active infrared detectors can be freely configured due to different environments, and it is flexible and convenient to use.
Passive infrared detectors are space-controlled detectors. Due to the poor penetration of infrared rays, there should be no obstructions in the monitoring area, otherwise it will cause a "blind area" of detection. In order to prevent false alarms, the passive infrared detector probe should not be aimed at any object whose temperature changes rapidly, especially the heating element. The detector should be given the maximum alert range so that possible intruders can be within the infrared alert beam range. The activity of the intruder is facilitated to cross the beam zone laterally, which can improve the detection sensitivity. However, when several passive infrared detectors are installed in the same room, they will not interfere with each other.
How to detect the reason why the detector does not alarm?
Use the walk detection method to trigger the detector to see if the indicator light of the detector flashes. If it does not light, it indicates that the battery needs to be replaced. If it means that the detection function is good, the host computer has not received it. Cause 1 The battery power is insufficient and the cause 2 detector is partially defective. , Cause 3 The host receives some defects.
How to adjust the detection distance of microwave infrared detectors?
The infrared detection range is changed by shorting the jumper. The infrared detection distance of the connected jumper is reduced by 50%. The detection distance of the microwave is changed by adjusting the potentiometer at the bottom right of the circuit board. The detection distance to the MIN direction decreases, the detection distance to the MAX direction increases, and the adjustment is made according to the site conditions to meet the usage requirements.
Host installation should pay attention to what issues?
The host installation should be away from large metal objects, TVs, computers, etc. Otherwise, the signal will be disturbed to shorten the distance of transmission or reception; the host should be installed as close to the detector as possible; under the premise of concealment, the antenna should be pulled out as far as possible. Put up; pay attention to the incoming and outgoing line of the phone.
Host Maintenance <br> <br> order to ensure the reliability of the system, at least once a month to keep the "pacing." After the mainframe has been used for a period of time, the main body may become dusty and greasy, need to be cleaned with a soft cotton cloth or sponge, and then wiped dry. However, during the cleaning process, it is forbidden to use any friction agent or organic solvent, such as kerosene, acetone, super glue, etc., to wipe the shell so as not to damage the appearance of the body and the transparency of the top window.
<br> <br> power supply mode from the external host mains AC adapter and a rechargeable built-in rechargeable battery. After the battery is under voltage, the power supply to the host will be turned off and the automatic protection state will be entered. Once the power of the system is restored, the host immediately starts to enter the working state, and the backup battery is charged.
What is a Fresnel lens?