Author: Shi Xinhua Source: far Extension Technology GB / T10488-1997 vibration intrusion detectors have been implemented as a national standard for three years, vibration intrusion detectors as technical protection means has gradually been recognized and applied. In order to better implement the GB / T10488-1997 national standard for vibration intrusion detectors and smoothly implement it, so that more people can understand the principles and applications of vibration intrusion detectors. Basic knowledge of intrusion detector principles and applications.
1 | The role of YT-SHK, YT-SHK-A, YT-JB3 vibration intrusion detectors in crime prevention since the reform and opening up, the crime situation has changed a lot with the flow of people, money, and materials . Many criminals have extended their criminal hands to banks, museums, ancient tombs and gun and ammunition depots, and have succeeded repeatedly. Dozens of cases such as Heilongjiang Province, Jilin Province, Shanxi Province, and Guangxi Province not only caused huge economic losses, but the theft of guns and ammunition also posed a major threat to public order. Analyzing these cases, we found that many of them were digging tunnels and breaking walls. The security members of the bank guarded the doors and windows extremely tightly, and 80% of the criminals who tried to enter the vault through the doors and windows failed to succeed. With no access to the front, they made up their minds on the weak links that could access the vault, such as underground pipes, vents, and basements. In order to deal with such crimes, banks reinforce the vault walls time and time again. When dense steel bars and high-grade cement were used to build a thickness of 50 cm, the number of wall excavation cases was significantly reduced. However, the thief is not dead, and can not be digged with ordinary tools, so he uses a plastic concentrated explosive that can be attached to the wall for directional explosion. Although the sound of this new explosive explosion is small, it is extremely powerful. The custodians only felt a slight shock and were not easily found when committing the crime. Some criminals also colluded with the design and construction personnel of the vault to specifically find the weakest parts for small-dose blasting, and the success rate of committing crimes was higher. In order to deal with such crimes, the custodians further strengthened the perimeter protection. So some criminals approached the vault by digging tunnels from a distance. Vibration intrusion detector came into being in this situation. After using this kind of detector in bank vaults, the number of cases that broke into the wall was indeed significantly reduced, so this kind of detector was quickly promoted.
On the basis of absorbing foreign experience and lessons, our company started the research of YT-JB3 vibration intrusion detector and YT-SHK vibration monitor as early as 1994, and put it on the market in 1996. Once the product came out, it was immediately recognized by all walks of life. It has been widely used in banks, cultural relics museums, troops and other systems. In the past few years, many major cases have been prevented, and great social benefits have been brought into play. Undoubtedly, a new sentinel has been added to prevent crimes in our country. In order to understand it, we must know its principle, structure, installation and use.
2 | YT-JB3 and YT-SHK Vibration Intrusion Detector Principle Analysis Vibration intrusion detector, also known as vibration measurement. Vibration measurement is an extremely complex technology. Because our environment is always in vibration. There are changes from the earth itself, such as volcanic eruptions and earthquakes; there are artificial mechanical vibrations, such as car train movements, machine tool start-up vibrations, etc., which brings great trouble to vibration measurement. Vibration intrusion detector is a door to detect the vibration signal caused by artificial mechanical impact on wall, ground and safe. Therefore, before analyzing the vibration intrusion detector, we must first understand the following problems.
2.1 What is vibration? When an object makes an oscillating motion relative to a reference position, the object is called vibration. In one second, the number of complete motion cycles is called frequency. Vibration amplitude is used to describe the characteristics of vibration intensity. The vibration amplitude is large, and the vibration intensity is also large. The vibration parameters—acceleration, velocity, and displacement—represent the unit of measurement.
2.2 YT-JB3 terminology of vibration intrusion detector â‘ Vibration intrusion detector-a detection device that can give an alarm to mechanical vibration (shock) caused by an intruder in the warning zone. â‘¡Vibration sensor-Vibration intrusion detector, a component that can sense vibration shock and convert it into electrical signal. â‘¢Adaptive amplifier-vibration intrusion detector, a component that can transform and amplify the electrical signal output by the sensor to the level required by the trigger. â‘£Trigger-In the vibration intrusion detector, the component that can convert the output level of the adaptive amplifier into the state of the relay switch.
2.3 Classification of Vibration Intrusion Detectors There are three types according to the warning objects: â‘ Vibration Intrusion Detectors for Buildings-When an intruder strikes a building, it can respond to the mechanical shock caused by it and generate an alarm signal. â‘¡ Ground sound vibration intrusion detector-a detection device that can generate an alarm to the vibration signal caused by the mechanical shock caused by the intruder walking on the ground or the vehicle running within the detection range. â‘¢ Vibration intrusion detector for safes-a detection device that can respond to the shock caused by it and generate an alarm signal when the safe is hit or normally opened.
2.4 Principle analysis of YT-SHK vibration intrusion detector 1. Composition of vibration intrusion detector The vibration intrusion detector is composed of four parts: vibration sensor, adaptive amplifier, trigger and power supply.
The principle of the vibration intrusion detector is not complicated, but certain measures must be taken in the circuit design to reduce false alarms: non-human impact vibrations are not alarmed, and artificial impact vibrations must be alarmed. This part is generally easier to understand, so I will not focus on it. Focus on the sensor, because it is the core of the vibration intrusion detector.
2. Sensors are the key components of vibration intrusion detectors. Vibration sensors are the key components of intrusion detection.
Vibration sensors are classified as follows: There are many types of sensors. Sensors used for vibration intrusion detectors include displacement sensors, speed sensors, and acceleration sensors.
2.5 Vibration analyzer, vibration analyzer, vibration recorder YT-SHK-A
Product description YT-SHK-A vibration analyzer adopts the principle of gyroscope vibration measurement, can measure small vibration and super strong vibration, can continuously monitor the vibration acceleration of the vibration object in three axes, and can display and analyze the data output. On the cash dispenser door of the ATM machine, when the safe door in the ATM machine is opened, it can detect and start monitoring video to accurately record the opening time.
Application range:
Transmission motors, cash machines, generators, transmissions, fans, turbines (gas, steam, hydraulic power, etc.), pumps, refiners, agitators, reciprocating generators, screw compressors, machine tools, separators, turbo compression Machine features:
High-speed acquisition: Adopt high-speed and high-precision acquisition and detection module, and the acquisition rate reaches? Millisecond level.
Digital output: The latest electronic technology is used to output the measurement results in three dimensions in a digital manner (RS 485), including effective, maximum acceleration, occurrence time, etc.
16bit D / A converter can get 80dB dynamic range. Capable of detecting subtle vibrations.
Product technical specifications:
Basic vibration probe: ADXL 335
Measurement method: acceleration Range: acceleration: +/- 2, +/- 3, +/- 4, +/- 5, +/- 6, +/- 8, +/- 16, +/- 70g
Measuring frequency range: Acceleration: 3Hz ～ 20kHz
Measured value range: Acceleration: 0.02 ～ 316m / s2 RMS
High-pass filter: 3Hz, 10Hz, 1kHz
Low-pass filter: 1kHz, 5kHz, 20kHz
Vibrometer mode: Simultaneously measure acceleration (effective value, single peak)
A / D converter: 16 bits, kHz sampling Processing items: Waveform Frequency range: 100, 200, 500, 1k, 2k, 5k, 10k, 20k Hz
Output mode:
1. Data output: RS485 mode: acceleration, occurrence time 2. Digital output: open circuit / closed circuit 3. Power output: DC 12V
Other environmental conditions: 0 ～ 40 ℃, 20 ～ 90% RH
Power supply: DC 12V
Size: (H) × (W) × (D) cm
Vibration intrusion detectors are all tested before leaving the factory. Due to transportation and other reasons, some deviations may occur. It is best to review them again. There are two ways to review. One is to check in the office, and the other is to actually install and check.
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