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Question and Answer 47 questions that security guards must know
Anti-theft alarm system is an essential subsystem of the security system. Today, the system introduces the basics of anti-theft alarm system and is suitable for novices.
First look at the two system diagrams
This picture shows the perimeter infrared alarm system
This picture shows the electronic fence system. So here's a brief talk about the basics of anti-theft alarm system
1) What are the parts of the alarm system?
Answer: A simple alarm system consists of a front-end detector, an intermediate transmission section, and a control panel. Larger systems can also regard the detector and the control panel as the front-end part. From the control panel to the alarm system, it is the transmission part. The central alarm module is regarded as the back-end part.
2) The alarm system can be divided into several types depending on the information transmission method.
Answer: According to different information transmission methods, there are two kinds of wired and wireless between the detector and the host. From the host to the central alarm can also be divided into two kinds of wired and wireless
3) What is a control panel?
Answer: Alarm Host: The “brain†part of the alarm system handles the detector signal and provides arming and disarming operations to control the alarm system through keyboards and other devices. In the event of an alarm, an audible/light indication can be provided, and the alarm can also be transmitted to the alarm center via the telephone line.
4) What are the common types of zones in the alarm system?
Answer: There are several types of common access zones, instant zones, internal zones, and 24-hour zones.
5) What is the access zone?
Answer: Access zones are also called delayed zones. After arming, the system will provide a certain time delay for the access zone. After the outgoing delay time expires, the delay zone system alarm is triggered. When the delay zone is triggered upon entry, the controller will beep during the entry delay time. As a warning signal for disarming the system, the system must be disarmed within the set delay time, otherwise it will alarm. This zone type is suitable for the user's entry/exit keyboard.
6) What is an instant zone?
Acknowledgement: Instant zone alarms are triggered immediately after the system is armed. There is no delay time.
7) What is an internal zone?
Answer: The internal defense zone: After the system is armed, if the internal zone is triggered and the internal zone is triggered, the internal zone will enter the delay state and will not alarm immediately. The delay time of the zone is the same as that of the access zone. If an internal zone is triggered before the access zone is triggered, the system will immediately report an alarm. This zone type is suitable for the user to manipulate the keyboard, such as detectors installed in the entrance, lounge or hall. It is suitable for guarding against intrusion in the hall before attempting to arm the system or attempting to enter and exit the zone.
8) What is a perimeter zone?
Answer: The surrounding defense zone is used for external departments and windows. When the defense zone is triggered, an alarm is issued immediately.
9) What is a 24-hour defense?
Answer: The 24-hour defense zone is not affected by arming and disarming. The defense zone is triggered and immediately alarmed.
10) What is the 24-hour sound emergency zone?
Answer: The 24-hour sound emergency zone is a kind of 24-hour defense zone. This type of defense zone is triggered. External warning lights and siren will give out sound and light prompts, and an alarm will be displayed on the keyboard. This type is suitable for emergency buttons.
11) What is a 24-hour silent emergency zone?
Answer: The 24-hour sound emergency zone is a kind of 24-hour defense zone. This type of defense zone is triggered. External alarm lights and siren do not give audible and visual alarms, and no alarm is displayed on the keyboard. This type is suitable for emergency buttons in important places such as banks and jewelry counters.
12) What is a fire zone?
A: The fire zone is a kind of 24-hour defense zone. The zone trigger triggers a fire alarm signal, the keypad displays the zone number and triggers an external alarm to sound a special alarm. For a 24-hour armed area equipped with a smoke detector, heat detector or emergency button.
13) What is outbound deployment?
Answer: Outbound Arming: A mode in which the user is armed when the user leaves the protection area of ​​the alarm system. In this mode, all zones in the system are in working condition.
14) What is Stay Arming?
Answer: Stay Arming: This refers to the mode in which the user is armed when the user is inside the protection area of ​​the alarm system. In this arming mode, all the surrounding defense areas in the system (such as the perimeter probe, window magnet, balcony curtain) The probes, etc.) are in the armed state, and the internal zone (usually an infrared probe installed in the room) in the system is automatically bypassed by the system. Internal personnel can automatically move within this zone without generating an alarm.
15) What is disarming?
Answer: Disarming means that the alarm host is released from the alarm state through a password or key method.
16) What is the elimination of the alarm?
Answer: The system had an alarm during arming. After the disarming, the system still has a prompt on the keyboard. Dismissing the alarm is to disarm the alarm and stop the alarm sound again, and return to the disarmed state.
17) What is the entry delay?
Answer: The entry delay refers to that when a person enters or exits the defense zone outside, the access zone is triggered, but at this time the system does not immediately alarm, but is in the entry delay state (usually tens of seconds). During this process, you must immediately disarm the alarm system. Otherwise, the system will generate an alarm when the delay time expires.
18) What is the outbound delay?
Answer: Outgoing delay refers to a delay time (usually tens of seconds) left for the operator to leave the access zone after the system is armed. You must leave the access zone during this time, otherwise you will trigger the access zone after the delay expires.
19) What is a bypass?
Answer: Bypass: Make one or more zones not armed when you arm.
20) What is the administrator password?
Answer: The password for the administrator to use, this password can enter the system programming, the system settings.
21) What is the owner password?
Answer: The password used by the system operator is the highest level password among all operator passwords. Through this password, the passwords of other users can be managed.
22) What is a duress password?
Answer: When the user is disarmed by the culprits under duress, the duress code can be used to operate the system. On this surface, the system is normally disarmed. In reality, the system silently transmits a duress alarm to the center.
23) What is a dual network alarm host?
Answer: The alarm host has dual communication functions of telephone line alarm and GSM wireless alarm. When the telephone line fails, the information can be transmitted automatically through the GSM communication module, and the two communication methods can also be used simultaneously. Greatly improve the reliability of information transfer.
24) What are the advantages and disadvantages of wired/wireless alarm systems?
Answer: The detector and host of the wired alarm system are connected through the data cable, and the host to the alarm center uses the telephone line or bus transmission mode. The wired alarm system has low cost, high reliability, and convenient maintenance, but it has the disadvantages of long construction period, large amount of work, and the like. Suitable for places with low requirements on the environment. The wireless alarm system is convenient for construction, aesthetics, etc., but has poor safety.
(1) The anti-interference ability is poor, and it is easy to cause false positives and false negatives due to high-frequency or same-frequency interference.
(2) Non-specialized installation, poor anti-vandalism. Almost all of the wired professional alarm consoles use a separate host and keyboard structure. The mainframe adopts a metal chassis and has a chassis tamper or integral tamper function. During the installation, the host generally recommends concealed installation. Only the keyboard is conspicuous and the keyboard has a tamper-proof function. This structure can better prevent intruders from destroying the host. Wireless alarm consoles are almost all integrated into the mainframe and keyboard (some without keyboards). They are made of plastic and have attractive designs. They are generally installed in more prominent positions. This type of structure is very vulnerable to intruders. And most wireless hosts use standard connector wiring. An intruder can stop an alarm simply by unplugging the telephone line alarm line.
(3) Backup battery problem. The wired host generally uses a 7AH battery, which can achieve continuous operation for more than 18 hours when a power failure occurs. Because of the volume problem, wireless hosts can only use small-size batteries, such as the 5th battery for backup. In order to reduce the cost of sales, some manufacturers do not use batteries when they leave the factory. Users use non-rechargeable batteries as backup batteries. Some manufacturers also use rechargeable batteries with relatively poor quality. After several times of charging, the battery supply time is greatly shortened, and the technical protection requirements for continuous power failure for 18 hours cannot be met. In order to save power, almost all wireless detectors use a trigger delay technique that is not triggered for a period of time after a trigger. This delay is usually 2-4 minutes. The intruder only interferes for the first time. The trigger has enough time to destroy the host.
25) What are the types of detectors? What are the common types on the market?
Answer: Infrared, microwave, vibration, smoke, gas, glass breakage, pressure, ultrasound, etc. The infrared detector can also be divided into active infrared and passive infrared, and the smoke can be divided into ion and photoelectric type. There are common infrared detectors (passive infrared), indirect shooting, fences (active infrared), double detectors, vibration detectors, glass break detectors
26) How does an active infrared detector work?
A: The active infrared detector consists of an infrared transmitter and an infrared receiver. The infrared emitter emits a beam or most of the modulated infrared light toward the infrared receiver. When there is no obstruction between the transmitter and receiver, the detector will not alarm. When an object is obstructed, the receiver output signal changes and the detector alarms.
27) How does a passive infrared detector work?
Answer: There are two critical components in the passive infrared detector. One is a Fresnel lens and the other is a pyroelectric sensor. Any object above the absolute temperature (-273o) in nature will produce infrared radiation, and the wavelength of infrared energy released by objects at different temperatures will also be different. The human body has a constant body temperature and differs from the ambient temperature. When the human body moves, this change in the difference is detected by the pyroelectric sensor through the Fresnel lens, thereby outputting an alarm signal.
28) What is the function of the Fresnel lens?
Answer: The Fresnel lens has 2 functions. One is to refract or reflect the infrared radiation of pyrolysis to the pyroelectric sensor. The other is to divide the detection area into several bright areas and dark areas. When the human body moves within the detection range, it will enter the Fresnel lens one by one. In the viewing zone, the pyroelectric sensor “sees†the moving human body for a while and then “sees†it, so that the human body movement can generate a continuously changing signal on the pyroelectric sensor in the form of a temperature change.
29) What is a dual infrared detector?
Answer: The detector that integrates two pyroelectric sensors with the same performance and opposite polarity is a dual detector.
30) What is a quad-ray detector?
Answer: The four-element detector is a detector that integrates four pyroelectric sensors with the same performance and opposite polarities.
31) What is temperature compensation?
Answer: In general, the human body temperature is always much higher than the ambient temperature. When the intruder moves, the sensor receives a large amplitude of the infrared change signal and triggers an alarm. When the ambient temperature rises close to the human body temperature, the amplitude of the infrared change signal received by the sensor when the intruder is in motion is very small, so that it may be because the signal is less than the trigger threshold and no alarm is given. Temperature compensation automatically increases the gain of the invader signal amplifier when the ambient temperature is close to the human body temperature, thereby keeping the alien intruder's signal from being captured, without affecting the sensitivity due to the ambient temperature.
32) What is analog pulse technology?
Acknowledgement: Analog pulse count: The detector measures the length of time the output signal exceeds the threshold. If the output of the amplifier exceeds the threshold for a preset length of time, an alarm signal will be generated. Pulse counting is generally adjustable from 1 to 3 levels. When the pulse count is 1, the sensitivity of the detector is extremely high. When the pulse count is 3, the detector has a low sensitivity but a strong false alarm prevention capability.
33) What is Digital Pulse Technology?
Answer: Digital pulse count: The detector counts the number of trigger edges triggered by the intruder from the beginning through the digital count, and triggers the alarm signal according to the preset number of digital pulse counts.
34) How does a microwave detector work?
Answer: The microwave detector is based on the principle of Doppler effect. In the microwave section, when transmitting at a frequency, when the emitted microwave encounters a fixed object, the frequency of the reflected microwave is not changed, ie, the signal is received and the detector does not send an alarm signal. When the microwave that is launched meets a moving object, the reflected microwave frequency will change, that is, the microwave detector will send an alarm signal.
35) What is Shuangjian detector? What are the common Shuangjian detectors on the market?
Answer: In order to overcome the deficiencies of a single technology detector, two kinds of detectors with different technology principles are usually integrated together. Only when the sensors of the two detection technologies detect the movement of the human body, the detector is called a double detector. . The common Shuangjian detector on the market is mostly microwave + passive infrared, and there are infrared + air pressure detectors and audio + air pressure detectors and other products.
36) What is Sanjian detector? What is a quadrant detector?
Answer: In order to further improve the performance of the detector, a detector that adds a microprocessor technology to the Shuangjian detector is called Sanjian detector. The addition of a second technology detector to the Sanjian detector becomes a quadrant detector.
37) What is a shock detector?
Answer: The vibration detector is based on the detection of vibration signals generated by intruders performing various sabotage activities. For example, intruders can cause these objects when they perform wall-cutting, hole drilling, and safe destruction. vibration. A detector that triggers an alarm with these vibration signals is called a vibration detector.
38) What are the common vibration detectors? What is its working principle?
Answer: According to the different vibration sensors used, the vibration detector can be divided into: mechanical vibration detector, inertial rod electronic vibration detector, electric vibration detector, piezoelectric crystal vibration detector, electronic type full vibration Detectors and other types. Recently, piezoelectric crystal vibration detectors are commonly used. The principle is to use the piezoelectric effect of a piezoelectric crystal. Piezoelectric crystal is a special kind of crystal, which can transform the mechanical force applied to it into a corresponding size electric signal. The frequency and amplitude of its electric signal are proportional to the frequency and amplitude of mechanical vibration, when the signal value reaches When the value is set, an alarm signal is issued.
39) How does a glass break detector work?
Answer: When the glass is struck and the glass is not yet broken, an ultra-low-frequency elastic vibration wave is generated. The mechanical vibration wave is lower than 20 Hz and belongs to the infrasonic wave. The loud and harsh sound produced by the broken glass is in the range of 10 to 15 KHZ, which is a high-frequency sound. When the detector detects both low frequency and high frequency sound frequencies, an alarm signal will be generated.
40) What is the detector standard output signal?
Answer: The detector standard output signal is a switch signal, normally open, normally closed, and normally open/normally closed.
41) What are the advantages of the detector's alarm memory function?
Answer: If more than one detector is connected to a zone, when an alarm event occurs, it is usually impossible to determine which detector is the alarm. With the alarm memory lock function of the detector, when an alarm event occurs, the alarm indicator will flash until the system is reset after the detector alarms. This will identify which detector is the alarm.
42) What are the advantages of magnetic shield relay?
Answer: The magnetic shield relay can prevent wireless electromagnetic interference and external interference. If the detector does not have a magnetically shielded relay, when the magnetic material is close to the detector housing, an external magnetic field can keep the relay open and send a false alarm signal, which in turn invalidates the detector.
43) What are the advantages of sealed optical systems?
Answer: It is possible to prevent small insects from creeping inside the lens and to prevent false alarms caused by air flow inside the detector (near the sensor). Prevents unwanted reflections inside the detector. Ensure the accuracy of infrared sensor focus.
44) How to choose the right IR product for the customer?
A: There are 2 points to consider when selecting a product. First, according to the environment of the perimeter, the environment can select two beams, and the poorer beam can select more beams. In addition, according to the distance of each straight segment of the perimeter, the alert distance should be selected. Combining the two parameters can select the appropriate product. In addition, according to the customer's appearance requirements, choose different shapes of the radio products.
45) What precautions should be taken when installing infrared radiation?
Answer: The shooting should be fixed on the mounting bracket. The mounting bracket should be firm to avoid shaking. The height of the installation is generally 30 cm above the guard surface. There must be no trees, birds or other small animals inside the cordon. When the same guard surface is installed with multiple sets of infrared radiation, cross reception should be avoided. Equipment access should be sealed and waterproof.
46) How to choose indoor detectors for customers?
Answer: The customer's environment can be better selected with infrared detectors, and the environment with poor choice of double detectors. Then select products with different detection distances according to the area that customers need to prevent. The infrared curtain detector can be selected for places where there is still activity after arming.
47) What should be noted when installing infrared detectors?
Answer: No object can be blocked in front of the detector. Avoid moving objects into the detection zone, avoid cold and heat sources, and avoid places where small animals frequently move to avoid reflections on the sun or sunlight.