preface
Hello everyone, I am Mr. Lin, infrared alarm system is composed of several infrared alarms an overall anti-theft system, infrared anti-theft alarm is divided into active infrared alarm and passive infrared alarm, is a practical self-defense deterrent alarm tool.
body
First, the difference between active infrared through-beam and passive infrared through-beam system
1. Active infrared through-beam
Active infrared alarm is composed of transmitter and receiver, transmitter is composed of power supply, light source and optical system, receiver is composed of optical system, photoelectric sensor, amplifier, signal processor and other parts.
The infrared rays emitted by the transmitter pass through the protection zone to the receiver, forming a cordon line. Under normal circumstances, the receiver receives a stable optical signal, when someone invades the cordon, the infrared beam is blocked, the infrared signal received by the receiver changes, extracts this change, amplified and properly processed, the controller sends an alarm signal.
Once a person or object blocks any adjacent two or more beams of light emitted by the transmitter for more than 30ms, the receiver immediately outputs an alarm signal, and when a small animal or small object blocks one of the beams of light, the alarm will not output an alarm signal.
Active infrared systems are generally used in perimeter prevention, and when choosing an active infrared alarm, you need to pay attention to the following problems:
1. The active infrared alarm is seriously affected by fog, and the equipment with automatic gain function should be selected for outdoor use (the sensitivity of such equipment will be automatically adjusted when the climate changes);
In addition, the detection distance of the selected equipment leaves a margin of more than 20% from the actual warning distance to reduce the false alarm caused by climate change of the system. Active infrared intrusion detectors should not be used outdoors in foggy areas, dirty environments, and large windswept sand.
2. When used outdoors, be sure to use a double beam or 3-beam active infrared alarm to reduce false alarms caused by animals, fallen leaves, etc.
3. When using active infrared intrusion alarms on fences, roofs or open areas, equipment with lightning protection function should be selected. When there is a broken wall and the distance is close, reflective devices can be selected to reduce the number of alarms.
Second, passive infrared through-beam
The passive infrared alarm is mainly based on the change of external infrared energy to determine whether someone is moving.
The infrared energy of the human body is different from the environment, when the person passes through the detection area, the alarm collects the position of this different infrared energy, and then through the analysis to issue an alarm.
The human body has a constant body temperature, generally around 37 degrees.
Passive infrared detectors generate alarms when they sense heat sources in three-dimensional space by using components sensitive to infrared frequency bands that are sensitive to human body temperature radiation.
Passive infrared detectors have the following technical weaknesses at a relative technical level:
1. It is easily disturbed by various factors such as animal body temperature radiation, sunlight irradiation, hot air flow temperature radiation and other factors to cause false alarms;
2. When the temperature is close to or higher than the human body temperature, this type of detector will not work normally at all. Due to the above technical reasons, passive infrared detectors are more prone to false alarms and false negatives than active infrared through-beam detection networks.
However, with the advancement of production technology and technology, as long as you can choose to use the appropriate infrared burglar alarm according to your actual environment, this situation will be greatly reduced.
Second, infrared through-beam wiring diagram
1. Bus system wiring diagram
Schematic diagram of bus host and infrared through-beam wiring
2. Infrared through-beam wiring diagram of split line
Third, the installation of infrared through-beam
1. Pipeline laying
1) Rigid PVC pipe for dark pipe, and metal pipe is selected for clear matching.
2) The dark piping pipeline should be laid along the shortest route to minimize bending. Pull wires in the adjacent area
Between boxes, S-bends or U-bends are prohibited. Dark piping buried in walls or concrete elements, which
The protective layer should not be less than 15mm.
Second, the thread and line mark correspondence
1. Before the cable is deployed, the insulation test should be carried out, and the insulation resistance value of the wire, cable and line to ground must be greater than 0.5MΩ, and it can be laid after passing the test.
2. The laying cables should be arranged neatly, not twisted, to minimize crossing, the thick line at the intersection is below, and the thin line is on the top.
3. There shall be no connector in the cable in the pipe, and the connector must be connected at the box (box).
4. Both ends of the laid cable must be marked.
5. When the wire pipe cannot directly enter the equipment junction box, the metal hose must be used to transition between the wire pipe outlet and the equipment wiring, the length of the hose shall not exceed 1m, and the cable shall not be directly exposed.
Third, infrared through-beam probe installation and initial adjustment
1. Fix the stainless steel bracket on the wall, thread the wire reserved in the box out of the tube with wire strippers to peel off the insulation skin, expose the core of 10mm~15mm (be careful not to touch the wire number sleeve), lead the cable in the box, crimped it on the terminal block of the detector, reel the remaining cable back into the box, and fix the detector base on the box with screws. The fixation should be firm and reliable.
2. When the active infrared detector is installed, the receiving and transmitting devices should be facing each other, and there should be no obstruction in the middle.
3. An anti-power supply can be equipped with 10 pairs of infrared through-beam interfaces, if the transmission distance exceeds 200m, the power supply should be installed in segments; Infrared thru-beam probes require a separate power supply. Other relevant requirements can be found according to the product manual.
4. Each boundary interface in the system should have a unique code corresponding to it, and it should be coded according to the product manual;