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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.”

With the continuous development of technology, mobile phones have become an indispensable part of our lives, but at the same time, the use of mobile phones has also brought some problems. On some occasions, people may need to block mobile phone signals to ensure information security, maintain order or other purposes. Cell phone signal jammers are widely used for this reason. However, it’s also crucial to know how to properly use and care for your cell phone jammer to ensure its long-term, stable operation and performance.

1. Use of mobile phone signal jammer
a. Reasonable circumstances
Before using a mobile phone signal jammer, you must first clarify the occasion where it will be used. Reasonable occasions include but are not limited to military areas, government agencies, prisons and other places where mobile phone signals need to be blocked. Make sure the use of jammers in these locations is legal and compliant.

b. Pay attention to the signal range
When using a mobile phone signal jammer, pay attention to its signal range and its impact on the surrounding environment. Make sure that the signal coverage of the jammer does not exceed the area that needs to be shielded, and try to minimize interference with normal communication equipment around you.

c. Comply with laws and regulations
When using a cell phone signal jammer, local laws and regulations must be strictly followed. Using the jammer without authorization or in illegal situations may violate relevant laws, resulting in legal liability and penalties.

d. Ensure safety
When using a cell phone signal jammer, make sure it is safe. Choose a regular and reliable jammer and operate it strictly in accordance with the instructions to avoid causing safety hazards or damaging the equipment.

2. Maintenance of mobile phone signal jammer
a. Regular cleaning
The mobile phone signal jammer may accumulate dust and debris during use, affecting its normal operation. Therefore, it is very important to clean the shield regularly. You can use a soft cloth to gently wipe the surface of the shield and make sure its vents are clean and clear.

b. Avoid getting wet
Cell phone signal jammers are usually made of electronic components, so try to avoid letting them get wet. Using or storing the shield in a humid environment may cause damage or reduced performance.

c. Pay attention to temperature and humidity
The working environment of the mobile phone signal jammer should be under suitable temperature and humidity conditions. Excessively high or low temperature and excessive humidity may affect the normal operation of the shield and even cause equipment damage.

① The higher the power, the better

1. The host frequency output is inaccurate, frequency drifts, the bandwidth is too wide, power is wasted, and interferes with the base station;

2. The simple frequency sweep power suppression method has low shielding efficiency and large radiation;

3. The power is falsely marked and exaggerated, and the nominal power loses its reference value;

4. Power is the foundation, technology is shutdown. Finding good methods and techniques is not as good as trying to gain power;

signal jammer

② Use directional antennas to avoid interference

1. There is a certain transmit signal strength outside the directional angle of the directional antenna, but it is much lower than the main lobe and is not completely directional;

2. Reflections from buildings will still cause external interference.

3. The host frequency drift seriously affects the base station and causes external interference;

4. TD full-time shielding interference must exist.

③ High-power equipment has large radiation, while low-power equipment has small radiation.

1. High-power uses an outdoor antenna, with long operating distance, large shielding coverage, uniform shielding signal but minimal radiation;

2. If low-power equipment does not use multiple antennas to provide long-distance shielding, but is centrally arranged or 5 antennas work together, its radiation power will be greater than 10 microwatts/square centimeter, and close-range radiation must seriously exceed the standard.

Wireless signal jammers can be divided into three levels according to the power size, and different application environments can use different power levels of shielding. One is the low-power type, that is, the transmitting power of each shield module is below 2-3W. The second is the medium power type, the transmission power is 10-20W. The third is the high-power type, that is, the transmitting power of the shielding module reaches 50W or even 100W.   signal jammer

High-power wireless signal jammers are typically used in outdoor open areas and larger open areas, while low-power types are used in indoor environments. In most cases, when the low-power network shield is installed outdoors, its effective shielding range is only 2-5 meters, after all, its transmission power is relatively low.

Power Strength: The power strength of the jammer is one of the key factors that affects the shielding range. Typically, the greater the power, the wider the shielding range. High-power jammers can cover a larger area and have a stronger impact on the target signal.
Frequency range: The frequency range of the interference signal emitted by the jammer also affects its shielding effect. If the jammer’s frequency range closely matches the frequency of the target signal, its shielding effect will usually be better.
Antenna Design: A jammer’s antenna design also affects its shielding range. A quality antenna design can improve signal transmission efficiency and coverage, thus extending the jammer’s shielding range.
Environmental factors: Surrounding environmental factors, such as buildings, topography, weather conditions, etc., will also affect the shielding range of the jammer. For example, dense buildings may impede the propagation of signals, limiting the jammer’s shielding range.
Target signal characteristics: The shielding effect of the jammer also depends on the characteristics of the target signal, including its power, frequency, modulation method, etc. Different types of target signals may respond differently to the jamming effects of the jammer.
Electromagnetic interference environment: In some cases, the surrounding electromagnetic interference environment may also affect the shielding range of the jammer. If there are other interference sources, it may interfere with the normal operation of the jammer, thereby reducing its shielding effect.

Common mobile phone signal jammers on the market have operating frequencies of: 869~894MHz; 825~960MHz; 1805~1880MHz and 1900~1990MHz, etc. The applicable frequency bands are CDMA800, GSM900, DCS1800, and PCS1900. It can control a range of about 40 meters in diameter, using a DC-DC converter input voltage and 5V output voltage. After turning on the signal jammer, garbled interference is formed in the message signal received by the mobile phone. The mobile phone cannot detect the normal data sent from the base station, so that the mobile phone cannot establish a connection with the base station. Mobile phones show symptoms such as searching the network, no signal, and no service system. The signal sending and receiving functions of mobile phones within the specified range are invalid, and outgoing and incoming calls cannot be made, thus achieving the purpose of mandatory ban.

signal jammer

Principles of mobile communication
The working principle of mobile phones is as follows: within a certain frequency range, mobile phones and base stations are connected through radio waves, and data and sound transmission are completed with a certain baud rate and modulation method.

Principle of mobile phone signal jammer (shielding device)
According to the communication principle, the jammer scans from the low-end frequency of the forward channel to the high-end at a certain speed during operation. This scanning speed can cause garbled interference in the message signals received by the mobile phone. The mobile phone cannot detect normal data sent from the base station, making it impossible for the mobile phone to establish a connection with the base station. Mobile phones show symptoms such as searching the network, no signal, and no service system.

Basic functions of signal jammer
1. After the slow start function is powered on, the working power supply rises from zero to stable within 4 seconds.

2. After the shielding function is activated, mobile phones within the range will be blocked within 35 seconds.

Application scope of signal jammer
Various examination rooms, conference rooms, gas stations, oil depots, churches, hospitals, courts, military sites, libraries, theaters and other places.

Mobile phone detection technology mainly detects when the electromagnetic wave signal emitted by the mobile phone when it is working causes the electromagnetic power in the area where the mobile phone is to increase to a set value, thereby determining that a mobile phone is working. This technology sounds very advanced at first, but in fact it is just a very superficial understanding. When this technology was proposed, the following issues were not considered:

signal jammer

1. Uncertainty of mobile phone transmit power

The specific base station through which a mobile phone enters the network when working is determined by the traffic volume and dynamic deployment of surrounding base stations. When the mobile phone is logged in and used, if the nearby base station is busy, it will log in to the idle base station farther away. The transmit power of the mobile phone will be adjusted accordingly according to the link loss of the mobile phone to the base station radio wave. Usually, the mobile phone receives the signal from the base station. The stronger the signal, the weaker the transmit power.

2. The distance between the mobile phone and the detector (link loss) is uncertain

The distance between the mobile phone and the detector and whether there are any obstacles in the middle will affect the strength of the signal received by the detector.

3. The intensity of space electromagnetic interference is uncertain

Common lightning, fluorescent lamps, electronic equipment, etc. are all sources of interference. At the same time, when mobile phones are working, there is a lot of out-of-band stray noise. Although the surface acoustic filter used in the detector is used on mobile phones, the filter has insufficient out-of-band suppression and is prone to cross-frequency phenomena. When used for detection, it cannot effectively filter out other interference signals, causing the detection system to be in chaos.

4. Detector setting sensitivity is uncertain

Generally, the sensitivity setting of a detector does not have a specific quantitative value. During debugging, adjust the sensitivity by constantly adjusting the position and dialing the mobile phone to observe whether the detector detects it.

 
In order to ensure the leading level of 5G network, the 2.6GHz frequency band is given priority to adopt the 100MHz networking solution design, which coincides with the operating frequency of the deployed TD-LTE system in the D1/D2 frequency band. In areas where TD-LTE frequency bands have not been cleared in the D1/D2 frequency band, 5G will encounter serious technical problems with LTE co-channel interference. In addition, according to the summary of 5G interference technology examples, 5G in the 2.6GHz frequency band will also encounter interference technology from the multi-channel microwave distribution system (MMDS) of the radio and television network, interference technology from video surveillance network transmission equipment, and pseudo base stations. Jamming technology and jammer jamming technology, etc. Therefore, studying and identifying 5G interference problems is of great practical significance to promote 5G interference technology to solve problems and ensure customer experience and business process understanding. signal jammer

1. LTE co-channel interference

In areas where TD-LTE in the D1/D2 frequency band has not been cleared, under long-term load conditions in TD-LTE residential areas, terminal equipment will cause increased co-channel interference in the same covered 5G residential areas, seriously affecting the characteristics of 5G Internet. The strength of LTE co-channel interference is closely related to factors such as the size of the covered area, the wireless network environment, and the traffic volume of LTE adjacent areas.

The main characteristics of LTE co-channel interference are that the 163~273PRB noise floor used in the D1/D2 frequency band increases significantly in the time domain, and the wave pattern characteristics show characteristics that are relatively highly related to the production scheduling optimization algorithm; in the frequency domain, the 24h interference immunity The pressure intensity fluctuates significantly with the freight volume and the trend analysis is basically consistent, showing significant frequency domain uncertainty.

2. MMDS interference

The multi-channel microwave distribution system (MMDS) uses microwave heating frequency to transmit at one point and receive at more points to transmit television, audio broadcast programs and data signals to the front or directly of each cable digital television public antenna television system. Microwave heating system software assigned to individual customers. According to the MMDS transmission configuration in my country, MMDS operating in the 2500-2700MHz frequency range will cause serious interference to the 5G system deployed in the 2.6GHz frequency band. The interference is characterized by several regular continuous 8MHz networks. Bandwidth Rectangular Box Interference Technology Wave Pattern.

In recent years, car and property theft incidents have occurred frequently in downtown areas. Through layers of radio waves, a car jammer simply modified from a micro-power radio transmitter interferes with the car owner’s ability to lock the door.signal jammer

At about 7:30 in the morning on July 17, 2015, Chen Qing (pseudonym) drove her child to Beijing Daxing 11 Jianhua Kindergarten.

Chen Qing recalled that it was raining heavily that day, so she parked the car and pressed the lock and hurriedly escorted her child into the kindergarten.

About 7 minutes later, Chen Qing returned and found her wallet stolen from the car. “I obviously got out of the car and pressed the lock!” In panic, she immediately called the police.

Chen Qing usually has the habit of opening the door to confirm whether the car is locked after parking the car. Because it rained that day, she ignored the details of locking the car.

After reporting the crime, the police reminded that Chen Qing was most likely to have encountered a thief who used a car jammer to commit theft. The theft suspect turned on the jammer not far from the vehicle, causing the door to fail to lock. When the owner left carelessly, he entered the vehicle to commit theft.

Chen Qing’s case is not an isolated case.

On the morning of February 23 this year, the police in Haidian District, Beijing captured two suspects, Guo Mouzhen and Guo Moufeng, who were suspected of using car jammers and other items to commit theft. In the suspect car, the police seized a large number of crime tools such as car jammers and screwdrivers, as well as suspected stolen items such as a laptop and a handbag.

The suspects Guo Mouzhen and Guo Moufeng confessed that when committing crimes, they chose to attack unattended high-end cars on the roadside, or used jammers to interfere with the owner’s locking of the car, or used screwdrivers and other tools to break the car glass, and then stole property. Since December last year, they have committed more than ten crimes in Haidian and Changping, stealing a total of more than 30,000 yuan in cash, several mobile phones, handbags, laptops and other items.

On May 9, 2016, the Beijing Haidian District Court tried a three-person gang that specifically used jammers to interfere with car owners locking their cars and then steal property in the car.

The defendant described that when committing the crime, the three of them held jammers and waited for the opportunity to stand on the opposite side of the road when a car stopped. At the same time, they turned on the jammer to release the “jamming signal.” After the car owner left, several people came forward to see if there was anyone left in the car. Once there is valuable property in the car, they open the door and steal it. Using this method, property has been stolen from many luxury cars such as Porsche, Audi, and BMW.

According to data from the China Judgment Document Network, since January 26, 2014, courts in various districts of Beijing have heard 26 cases involving the use of car jammers to commit theft.