カテゴリー別アーカイブ: 未分類

In order to ban students from using mobile phones, a private middle school in Zhengding County (Hebei) installed multiple mobile phone signal jammers on the roof of the school’s teaching building. Now the students can no longer use their mobile phones, but because the instrument is located on the roof and the surrounding area is very empty, surrounding residents have also been seriously disturbed when using their mobile phones. On March 25, the Shijiazhuang Radio Administration Bureau of Hebei Province ordered the school to dismantle the rooftop equipment in accordance with relevant regulations. However, the school stated that the use of mobile phones has a great negative impact on students’ normal learning, and how to effectively supervise it has become a problem.

Complaint: Cell phones frequently malfunction around the school

According to an operator in Zhengding, for a long time, the company has frequently received reports from residents in the northeastern area of Zhengding County that their mobile phones often appear intermittent when making calls. The company sent personnel to check the signal base station many times and found no problems. Therefore, it sought help from the Shijiazhuang Radio Administration Bureau to investigate the sources of radio signal interference in the area.  signal jammer

On March 25, the Shijiazhuang Radio Administration Bureau sent law enforcement officers and radio monitoring vehicles to the northeastern part of Zhengding County for testing. After investigation, the staff initially detected that the signal interference was strongest at a private middle school in the northeastern area of the county. When the staff talked with residents around the school, they confirmed that the problem of mobile phone use in the area was indeed serious, but the residents did not know the reason.

Install shielding equipment on school roof

Detection by radio direction finding and positioning instruments showed that the source of interference was on the campus of this private middle school. After entering the campus, the staff discovered that all the buildings in the school were bungalows, and a yellow box-like device was installed on the roof of many of the teaching buildings. Tests with professional instruments showed that the device emitted radiation with a strong frequency, and the signals from the mobile phones carried by the staff completely disappeared. The school admitted that the device was a “mobile phone signal jammer” and that the jammer was turned on because the senior high school students were taking a mock exam that day. It is reported that the transmitting frequency of this instrument has multiple frequency bands such as 800 MHz and 1800 MHz. These frequency bands include frequency bands used by communication operators.

According to the school leaders, students’ use of mobile phones affects their studies. In order to ban the use of mobile phones, the school invested heavily in purchasing and installing “mobile phone signal jammers” and installed them on the roof. “I didn’t expect it would have an impact on the lives of surrounding residents,” the person in charge said. The instrument’s packaging clearly stated that the effective range is 30-50 meters. “How could the impact range be so large?”

According to the staff of the Radio Administration Bureau, since the installation site is on the roof and there are no surrounding buildings to block it, when the jammer is turned on, the interference range will expand.

According to reports, there are relatively strict regulations on the use of mobile phone signal blocking devices, and they can only be used in major national examinations, high-level meetings and other occasions. This private middle school also uses this kind of equipment in daily teaching, which affects the normal lives of surrounding residents. The Shijiazhuang Radio Administration Bureau ordered it to remove the mobile phone signal jammer in accordance with the law.

Supervision of students’ use of mobile phones is a problem

The person in charge of the private middle school said that the use of mobile phones has a great negative impact on students’ normal learning. The only purpose of many students using mobile phones is for entertainment, playing games, chatting online, and even looking for pornographic information. Many teachers are very worried. “The school cannot search one by one at the school gate, nor can it monitor every student 24 hours a day. There are great difficulties in monitoring mobile phones. After we purchased these devices, students’ use of mobile phones has been greatly reduced.” However, high-tech means are relied on to interfere with mobile phones. The signal was not allowed by the national radio management department, and the school expressed its helplessness.

A parent of a high school student also told reporters that for the convenience of communication, he once gave his child a mobile phone with the simplest functions, but within a few days his child asked for a high-end mobile phone. “My classmates often joked that his mobile phone could not keep up. “Era,” the parents were very angry after hearing their children’s story. Not only did they not buy new mobile phones, they even confiscated the old ones. “Mobile phones have become something for students to satisfy their vanity.”

A sophomore girl from Shijiazhuang No. 2 Middle School told this reporter that the No. 2 Middle School did not completely ban students from using mobile phones. It only stipulated that use is prohibited in the teaching building. There are no requirements outside the teaching building. Students use mobile phones voluntarily. Some parents believe that as long as their children can control themselves, there is no problem in using mobile phones, but necessary supervision is still needed.

So, how can schools effectively supervise students’ use of mobile phones? Professor Shi Guoxing from the School of Education of Hebei Normal University said in an interview with reporters that mobile phones do more harm than good to the learning of students, especially primary and secondary school students with relatively poor self-discipline, so it is necessary to restrict their use. Although the practices of this private middle school in Zhengding have affected the lives of residents outside the school and should be corrected, it is also a helpless move by the school. Since cell phones cannot be kept out of school by blocking signals, it is recommended to use more diversion methods, adopt a compromise plan, make different requirements for different students at different times, and standardize the use of students’ cell phones through the joint efforts of parents and teachers. .

United States: Opposition to the use of mobile phones on campus is strong. Currently, most schools in the United States do not allow students to use mobile phones. In Georgia, students are strictly prohibited from using mobile phones before school ends at 15:00. Once a student violates the rules, the teacher can confiscate the phone and impose disciplinary penalties on the person involved.

Finland: Selling mobile phones to teenagers is prohibited. The Finnish Market Court recently decided to prohibit Finnish wireless communication companies from directly selling mobile communication services such as mobile phone access to the Internet to teenagers. Violation of this ban will result in a fine of €100,000.

UK: The British Ministry of Education sent a letter to principals of schools in the UK, making it clear that except in emergencies, students under the age of 16 are not allowed to use mobile phones. A government research report “Mobile phones may harm children’s health” is also attached to the letter. . There is no clear evidence in the report that the radiation from mobile phones is harmful to the human body, but it is believed that because children’s nervous systems are not fully developed, their heads are smaller, their skulls are thinner and other physiological reasons, they will absorb more radiation from mobile phones, which is harmful to health. constitutes an “undetermined” hazard.

A signal jammer is an important electronic device used to block the transmission of wireless communication signals. In modern society, we sometimes need to use signal jammers to cut off wireless communications and prevent information leakage. Therefore, the debugging of signal jammers is crucial. This article will introduce you to several common signal shielding instrument debugging techniques to optimize the stability of the equipment’s operation.  signal jammer

1. Make sure the device is connected correctly. First, check whether the signal shielding device is connected correctly to other devices. Signal jammers usually need to be connected to radios, antennas and other equipment. Make sure that all interfaces are connected firmly and correctly to avoid signal instability or failure to shield during the operation of the signal shielding device.

2. Check the power settings of the signal jammer. The power setting of the signal shielding device is crucial for stable signal shielding effect. During the debugging process, we can reduce the power of the signal shielding device to observe whether the signal is intermittent. If the signal shielding effect is not good, you can gradually increase the power until the ideal shielding effect is achieved.

3. Find possible sources of signal interference. During the debugging process of the signal shielding instrument, we need to investigate possible sources of signal interference. Common sources of interference include electronic equipment, communication facilities, etc. By eliminating these interference sources one by one, we can more accurately locate which device or signal is interfering with the work of the signal jammer. Once the source of interference is found, appropriate measures can be taken to solve the problem, such as changing the location of the equipment or adding shielding materials.

4. Use appropriate shielding materials. Signal jammers typically use one or more materials to block wireless communication signals. Choosing the right shielding material is crucial for debugging the signal shielding device. Different materials have different shielding effects and transparency. We need to choose the appropriate shielding material according to specific needs and ensure its quality and durability.

In mobile phone shielding projects, the reasons for different signals caused by external and environmental factors are:
1. Due to the different power and number of channels of base stations such as China Mobile, China Unicom, and China Netcom, the distance between the base station and the prison, and the different sizes of other nearby buildings, topography, and landforms, the signals in the prison area are also different.  signal jammer
2. Due to the different characteristics of the actual use environment, the direction, power, distance and distance of each base station, there may be dozens of channels for the user’s mobile phone to automatically select in the same environment. At the same time, there are spatial field strength differences indoors and outdoors. Ground and metal Objects cause very complex adverse effects on signals blocked by mobile phones. So we all have this experience, for example: (a) In different areas, some mobile signals are strong, and some China Unicom signals are strong: (b) Even in the same place, the signals are also different, some are strong and some are weak, so mobile phones The signal shielding system is a highly professional system project.
Measures taken for the above reasons:
1. Conduct a detailed on-site survey of the prison environment, topography, landforms, etc., very carefully. The survey needs to shield the regional environment, understand the actual requirements of the customer, and design personalized solutions. Therefore, special project investigation and solution must be carried out to comprehensively solve problems for customers in a scientific and systematic manner.
2. Thoroughly analyze the local signal distribution and building structure. It is positioned using non-general equipment and measured by a series of instruments. Choose different composite antennas based on the organic combination of antenna application principles in different frequency bands.

In the digital age, mobile phones have become an indispensable communication tool for everyone. However, in certain situations such as examination rooms, conference rooms, etc., communication may cause bad results. Therefore, a high-quality and efficient mobile phone shielding system is particularly important. This article will delve into the relevant strategies and technologies for building a high-quality and efficient cell phone blocking system.   signal jammer

The necessity of mobile phone blocking system
Cell phone blocking systems, as the name suggests, are devices used to cut off cell phone signals to prevent communication devices from being used in specific areas. In the examination room, the mobile phone signal blocking system can prevent the occurrence of fraud; in the conference room, it can ensure the confidentiality of the meeting and not be disturbed; in areas such as prisons, it is part of the security management to prevent the occurrence of illegal communications . Therefore, the role of mobile phone blocking systems in different fields cannot be underestimated.

Principle of shielding system
To understand a quality cell phone blocking system, you first need to understand its basic principles. Simply put, mobile phone shielding devices interfere with the normal reception of mobile phone signals by emitting the same frequency signal that communicates with mobile phones, making the mobile phone unable to make and receive calls normally. This principle is similar to playing multiple sound sources in a room, eventually leading to the inability to recognize the original sound.

System Design Considerations
1. Environmental adaptability. Before designing a shielding system, the first thing to consider is environmental factors. Different environmental conditions, such as wall material, space size and surrounding electromagnetic environment, will have a significant impact on the shielding effect. Therefore, environmental conditions should be fully considered at the beginning of the design to ensure that the screen system can adapt and operate efficiently in the specific environment.
2. Coverage. Considering shielding range is another key point in the design of a quality and efficient mobile phone shielding system. Designers need to determine the screen range through calculations and ensure that the signal completely covers the area where the screen is required, while avoiding any impact on normal communications in surrounding areas.
3. Legal compliance. The country has strict laws and regulations on communication signal shielding. When designing a shielding system, you need to strictly abide by relevant laws and regulations. You cannot shield signals at will, otherwise you may be suspected of violating the law. Therefore, designers need to understand and follow local regulations and standards in detail when building screen systems.
4. Technical parameters. Technical parameters are the top priority in building an efficient mobile phone shielding system. This includes the frequency, power, size, signal emission stability, etc. of the mobile phone signal shielding system. These technical indicators affect the quality of the shielding effect and whether it can work stably and for a long time. High-quality technology and components must be used to build a mobile phone shielding system that is both safe and reliable.
5. User interface and ease of operation. Taking into account the user’s operating habits and convenience, a friendly user interface can be integrated into the mobile phone shielding system to ensure that even non-technical personnel can quickly understand and operate. At the same time, necessary operation guides and fault diagnosis tools are provided, which can greatly improve the user experience of the system.

In a prison environment, maintaining security and control over communications is critical. Cell phone signal blocking systems not only prevent illegal communications but also enhance overall security management. This article will introduce in detail the installation steps, maintenance points and solutions to common problems of the mobile phone signal blocking system in prisons.  signal jammer

Detailed explanation of steps 1. planning and design

Needs Assessment: First, assess the type and number of shielding systems required based on the prison’s layout, building materials, and signal coverage needs.

System Design: Design a comprehensive installation plan including equipment location, power configuration and signal coverage.

2. Installation process

Equipment placement: Install the signal jammer at the designated location according to the design drawings. Make sure all equipment is installed in a location that maximizes coverage area and is less likely to be vandalized.

Power connection: Connect to a stable power system. For equipment that requires high power output, ensure that the power line is safe and reliable.

3. System configuration

Frequency settings: Set the frequency and power of the shielding system according to the prison’s internal communications policy and external regulations. Ensure settings comply with legal requirements while effectively blocking illegal communications.

Testing and debugging: After completing the initial installation, conduct system testing to check whether the signal coverage is uniform and effective. Adjust device settings until optimal performance is achieved.

4． final acceptance

Performance verification: Test system performance multiple times at different times and under different weather conditions to ensure stable operation under all circumstances.

Documentation archiving: Record installation details, configuration settings, and test results to provide reference for future maintenance and upgrades.

The United States’ confidence in the Iraq war is largely based on high-tech military equipment. Guided bombs such as JDAM can theoretically carry out precise “surgical” strikes against hostile parties. The Iraqis used low-cost signal jammers in an attempt to jam the mythical Global Positioning System (GPS) weapons guidance signals.  signal jammer
This kind of GPS jammer is only the size of a mobile phone and can be purchased in the market for a few hundred dollars. The Iraqis regard it as a magic weapon to “defeat foreign artillery” – it is said that it can interfere with the GPS signal, thereby allowing the Americans to accurately The weapon was “hitting crookedly.” It is said that the US military has found and destroyed 6 such jammers in Iraq.

The US military’s “Global Positioning Satellite System” is a signal network composed of 27 satellites. It can not only position and control weapons, but also provide navigation for troops and aircraft accurate to meters. If the GPS signal can be interfered with for a long time, it will cause the entire logistics system of the US military to malfunction.

Before the war began, U.S. military experts warned that the Iraqis’ GPS jammers might disable U.S. guided bombs. Douglas Lowero, the person in charge of the GPS system program in the United States, believes that this is nonsense. There is no instrument on the market that can effectively interfere with GPS signals.

How powerful is this gadget?

A Russian company makes such a cheap GPS jammer. Theoretically, this jammer can interfere with satellite signals within a radius of 200 kilometers. The signal sent by U.S. navigation satellites to the GPS receiving antenna is very weak, and its strength is only about one billionth of the signal received by a general TV antenna. Therefore, satellite navigation systems commonly used in automobile transportation, navigation and adventure travel are very susceptible to interference from such GPS jammers. However, navigation equipment used for military purposes is relatively “robust” and less susceptible to interference.

The “C/A” code of the GPS system is used for civil purposes, and its positioning accuracy can reach about 5 meters. The military uses the “P” code, which has a positioning accuracy of up to one meter.

Not only is the military’s “P” code more precise, it’s also encrypted and therefore less susceptible to interference. Douglas Lowero believes that military GPS codes are thousands of times more resistant to interference than civilian codes. He said that GPS jammers are only effective within a radius of a few kilometers. At most, they can only interfere with GPS-guided weapons within this range, and it is impossible to make guided weapons stray.

In addition to satellite positioning systems, the U.S. military’s precision weapons are also equipped with another navigation mechanism-the Inert Navigation System (TNS). The TNS system will not be interfered by external signals. Its working principle is to use the inertia of the high-speed rotating gyro system for positioning. Before the precision bomb is launched, the TNS system is input with a set of parameters that define its starting position; after the bomb is launched, the gyro system interprets each trajectory change relative to the starting position as a steady-state disturbance, thereby performing a new position calculation. describe.

The positioning error of a GPS-guided bomb is about 3.5 meters, while the positioning error of TNS is about 20 meters. If used to attack military installations, this positioning error of TNS can be ignored. However, if it is used to attack military targets in residential areas, the possible consequences of this error cannot be underestimated.

The mobile phone signal jammers purchased by the school in previous years did not have the function of interfering with 5G signals because 5G had not been launched when they were originally purchased. In the current use of signal shielding in examination rooms, they can no longer shield 5G signals. This leaves school examination room users faced with the problem of how to upgrade or replace the original mobile phone signal jammer. So how should you choose a 5G signal jammer during school exams? signal jammer
School examinations require the use of 5G signal jammers for examination room management to ensure that candidates will not be affected by wireless signals from the outside world. Therefore, it is recommended to consider the following points when choosing a 5G signal jammer for school exams:

1. First, make sure that the selected 5G signal jammer can block the signal in the 5G frequency band. Generally speaking, the frequency bands of 5G signals are divided into mobile 5G (2515MHz-2675MHz, 4800-4900MHz), China Unicom 5G (3500MHz-3600MHz), China Telecom 5G (3400MHz-3500MHz), radio and television 5G (703MHz-733MHz, 758MHz-788MHz, 4900MHz -5000MHz), so you should purchase a jammer that supports these frequency bands.

2. Choose a brand or model with good shielding effect. You can refer to some well-known domestic and foreign brands or models with a certain reputation in this field for comparison. Of course, you should also choose a signal jammer model with appropriate power based on your own usage scenario and environment to purchase a 5G signal that suits your needs. jammer.

3. Consider purchasing a multi-functional model that has other functions besides shielding, such as shielding GPS, Bluetooth, WIFI and other wireless signals, in order to adapt to the shielding requirements of different types of communication equipment in exam scenarios.

4. Finally, the price of the signal jammer must be considered. After all, the budget cost of some school examination rooms is limited, so it is necessary to choose signal jammer products with high cost performance. Of course, in addition to considering the price, the quality and performance of the 5G signal jammer should be given priority. Choosing a high-quality and high-performance 5G signal jammer can provide better protection and security for the exam process.

How to block your child’s cell phone signal? Many children have been exposed to various electronic products since birth, which is actually harmful to the growth and development of children, so we all need to keep children away from mobile phones in a timely manner.

Especially from last year to this year, due to the impact of the new coronavirus epidemic, many children have become accustomed to playing mobile phones at home and using computers to play games online. Having a signal jammer can help children slowly quit the habit of surfing the Internet and have better control. The amount of time children spend online. At the same time, adults can also spend less time using mobile phones and interact more with their children and their families. Helps improve family happiness index.

signal jammer

So how to block children’s mobile phone signals and control the time when children use the Internet?

Method/Step 1: Restrict children’s mobile phone access to the Internet in the router
Currently, all types of routers can filter the MAC address of mobile phones in the security settings. In this way, children’s mobile phones can be prohibited from accessing the Internet.

If you are more flexible, you can use the router to limit the time period for children to access the Internet, as well as the Internet speed, etc. Most current routers have this feature. By limiting the Internet speed, children can only check information when using mobile phones, but cannot play games.

Method/Step 2: Turn off mobile data service
Using the previous method, you can restrict the child’s mobile phone from connecting to the home Wi-Fi to access the Internet, but what should you do if the child can still access the Internet using data traffic? At this time, contact the operator and turn off the data service function of the child’s mobile phone, so that the child’s mobile phone can only make calls. Phone calls and text messages are now available, and the service is free.

If the child needs to access the Internet, we can turn on the hotspot on the mobile phone for the child to use temporarily, and then turn off the hotspot after use.

Method/Step 3: Use a signal jammer
Wireless networks make it easier for people to access the Internet, but the problems caused by them cannot be ignored. It’s not just a matter of access to the network, it’s also a matter of network security. In order to maintain a good network environment, signal jammers are installed in many places to prevent excessive network usage. This equipment has been widely used in countries and regions around the world. Schools, prisons, libraries, reading rooms and gas stations are typical examples.

Vehicle-mounted signal jammer equipment is an interference device installed on a vehicle. It is mainly used to shield or interfere with the signals of wireless communication equipment, such as mobile phone signals and remote control signals. During use, its interference effect is directly related to whether the task can be successfully completed, so it places very strict requirements on the vehicle-mounted signal jammer equipment itself. The factors that affect the interference effect of the vehicle-mounted signal jammer include the following aspects.    signal jammer

1. Signal strength at the use site: The signal interference range of the vehicle-mounted signal jammer equipment is affected by the signal strength at the site. The on-site signal strength is mainly determined by the distance of the base station and is closely related to the strength of the mobile phone signal. However, different mobile phone operators also have different strategies for signal distribution, making signal quality difficult to predict. Therefore, when setting up a vehicle-mounted signal jammer device, the spectrum distribution and signal strength can be measured to select specific modules to maximize the interference range, or contact the operator to reduce the signal strength on site. For other remote control signals, the interference effect depends on the distance between the signal source and the suspected explosive, which is difficult to predict. Therefore, the focus should be on shielding the remote control signal so that the interference remote control signal module of the vehicle-mounted signal jammer device can interfere seamlessly.

2. The transmit power of the radio frequency module: The interference effect of the vehicle-mounted signal jammer device is also related to the transmit power of the radio frequency module. The greater the transmission power, the greater the interference range. However, if the bandwidth of the signal transmitted by a single module is too wide, the interference effect will also be affected. In order to achieve the best interference effect, high-power radio frequency modules should first be selected, and secondly, the frequency bandwidth of the signal transmitted by a single module should be reasonably allocated to maximize the interference range.

3. Adaptability of vehicle-mounted signal jammer equipment: The types and frequencies of wireless signals interfered by vehicle-mounted signal jammer equipment vary, so the adaptability of vehicle-mounted signal jammer equipment is particularly important. Vehicle-mounted signal jammer equipment should have interference adaptation capabilities for various wireless signal types and frequencies, so that it can exert the maximum interference effect in various environments and ensure the safety and stability of the equipment.

4. Interference from the vehicle itself: The vehicle-mounted signal jammer device itself will also produce a certain amount of electromagnetic wave interference, which may have an impact on other electronic equipment. Therefore, additional shielding or isolation measures are sometimes necessary to reduce the effects of internal interference in vehicle-mounted signal jammer devices.

Cell phone signal jammers are not the latest scientific invention, but the high demand in the US market has driven dealers to stock up on them. Users of mobile phone signal jammers include coffee shop and barber shop owners, restaurateurs, theater operators, bus drivers and daily commuters who use public transportation to and from get off work.

signal jammer

This device is only as big as a cigarette box and is very convenient to hide. Users only need to press a button, and the device will emit a radio interference signal, blocking the communication between all mobile phones and signal towers within a radius of 4.5 meters to 9 meters. Cell phone users experiencing signal interference will immediately see the words “No Network Available” on their screen. Cell phone jammers range in price, from $50 to several hundred dollars, and the radio signal they emit varies in strength. The more expensive the mobile phone signal jammer, the wider the range it can affect.

However, U.S. law prohibits private blocking of signals and imposes fines of up to $11,000 on first-time violators. According to the New York Times, relevant U.S. departments have investigated many companies that manufacture such devices and have also held many users accountable.

The U.S. Wireless Industry Association submitted an opinion to the Federal Communications Commission on November 3, requesting that the regulations “prohibiting private signal blocking” be retained. Not long ago, two American companies proposed to the Federal Communications Commission that signals should be blocked in relevant places, such as prisons. But network companies from the Wireless Industry Association believe that lifting the regulations may allow criminals to abuse signal jammers, making it impossible for cell phone users to make calls for help in emergencies. Supporters of retaining the regulations also argue that blockers “punish” not just those who make noise, but also harm callers who deliberately speak quietly.

FCC spokesman Clyde Enslin declined to comment on the controversy or last year’s findings in Maryland. Jeffrey Nelson, a spokesman for Verizon Communications, which spends $6.5 billion a year on network system maintenance, commented: “This is a counter-intuitive approach: when mobile phone user demand increases due to better wireless network signal coverage, When it went up, those businessmen who made jammers also saw a market.”