カテゴリー別アーカイブ: 未分類

In modern society, cell phones have become an integral part of people’s lives. However, the popularity of cell phones has brought new challenges to prison management. Prisoners’ illegal use of cell phones for criminal activities, planning jailbreaks, or other illegal communications poses a serious threat to prison security management. In response to this problem, the New South Wales (NSW) Justice Department in Australia worked with Kordia Solutions to use advanced cell phone jamming technology to effectively curb prisoners’ illegal use of cell phones. This article will explore the application of this technology and its legal and management significance.  cell phone jammer

1. Background and Problems
The illegal use of cell phones in prisons has become a global problem. For example, in California, it is a misdemeanor for prisoners to possess or attempt to smuggle a cell phone into prison, and offenders may be fined $5,000 per device. In Australia, the NSW Justice Department also faces this challenge. To combat this illegal activity, the NSW Justice Department decided to use wireless technology to block wireless technology, that is, to prevent prisoners from using cell phones by installing a cell phone jammer system.

2. Kordia Solutions’ Jamming Technology
Kordia Solutions is a leading network service provider specializing in the design and installation of various communication systems. Under a contract from the NSW Justice Department, Kordia Solutions designed and installed mobile phone jammer systems at two correctional institutions, including Lithgow and Goulburn Correctional Centres. The contract is worth $7.25 million and is intended to continue the jammer trial that began five years ago.

Technical implementation: Kordia Solutions installed a jammer system at Lithgow Correctional Centre, which uses a low-power antenna to emit a jammer signal to prevent mobile devices in the prison from successfully connecting to nearby telephone towers. This technology ensures that mobile phones in the prison cannot communicate normally.

Federal authorities in South Carolina recently announced a life sentence for Daniel Allen Shannon, 43, of Lexington, for a prison cell phone incident. This incident highlights the need for cell phone interference in prisons, as inmates are using contraband cell phones to continue their criminal activities.

Shannon is currently in custody of the South Carolina Department of Corrections (SCDC) and is ineligible for parole for his conviction for the 2001 kidnapping, robbery and murder of a Lexington restaurant manager. According to his prison criminal record, Shannon has attempted to escape SCDC custody multiple times, most recently last month when he was found with a weapon. In January 2020 and December 2021, he was cited for “possession or attempted possession of a cell phone.”

cell phone jammer

Federal prosecutors noted that Shannon used contraband cell phones to coordinate the distribution of large quantities of methamphetamine in Lancaster and Kershaw counties. More seriously, he also carried out assassinations in prison. After believing one of his drug couriers was robbed, Shannon sent his accomplices to retaliate, resulting in the shooting death of a Kershaw man in September 2019. Shannon then ordered his accomplices to burn down the residence where the murder took place and dispose of the victim, whose body was found dumped on the side of a highway in Westerville, South Carolina.

“This case illustrates the extreme dangers posed by the presence of contraband cell phones in our prisons,” U.S. Attorney Adair Ford Burroughs’ office noted in a press release. “We will not sit idly by while inmates use these phones to commit violence, drug trafficking, sex crimes, and fraud, and we will work with our federal and state partners to vigorously prosecute these criminals and protect the public.”

Shannon was federally indicted in February 2022 and pleaded guilty in February 2023. This month, U.S. District Judge Sheri Layden sentenced him to life in prison, but the sentence will only take effect “upon his release from a South Carolina prison.” Shannon is ineligible for parole due to his multiple convictions.

The incident revealed the urgent need for prison cell phone interference. Inmates using contraband cell phones not only endanger public safety, but they can also continue to engage in illegal activities inside and outside prisons. South Carolina Prison Superintendent Brian Sterling and U.S. District Court Judge Sheri Layden are both vocal advocates of cell phone jamming.

In response to Shannon’s conviction, Sterling said, “This is yet another example of an inmate using a contraband cell phone behind the fences of a state prison to continue committing crimes.” His comments are supported by many legal and security experts who believe that preventing inmates from accessing and using cell phones is a key measure to maintain prison order and public safety.

In public discourse, individuals and institutions often cling to bad ideas, try to rationalize or explain them away, or suddenly change their mindset without explanation. Such practices do not build trust with audiences in the marketplace of ideas. Admitting mistakes or reconsidering previous positions when prompted by new information is critical.

For example, while I was once a staunch opponent of voter ID laws, over time I came to recognize the importance of “one person, one vote” and the failure of the current system to uphold that ideal. Similarly, I opposed cell phone jamming around Palmetto State Prison until I realized that the so-called public safety objections of wireless service providers pale in comparison to the threat posed by violent inmates with these devices.

The case of Daniel Allen Shannon is a warning, revealing the serious harm of contraband cell phones in prisons. Although wireless service providers profit from prepaid calls and minutes, such economic interests should not override public safety. The federal authorities’ life sentence for Shannon is not only a sanction against individual criminals, but also a strong response to the problem of contraband cell phones in prisons.

In the future, governments at all levels and relevant departments should continue to strengthen the implementation of cell phone interference in prisons to ensure that prisoners cannot use contraband cell phones to continue crimes, thereby better protecting social public safety.

Detecting whether there is a mobile phone jammer working nearby requires certain technical means and methods. cell phone jammers interfere with the communication between mobile phones and base stations by emitting radio signals of specific frequencies, so that mobile phones cannot receive or send signals. The following are detailed detection methods and precautions.

Mobile phone jammers usually work in the following ways:
Frequency interference: The jammer emits radio signals of the same frequency band as the mobile phone, thereby interfering with the communication between the mobile phone and the base station.
Signal shielding: Create a signal shielding area in a specific area so that the mobile phone cannot receive the signal from the base station.

Methods for detecting mobile phone jammers
1. Detection using the mobile phone’s own signal status
Signal loss phenomenon: In an environment with normal signal strength, if the mobile phone signal suddenly disappears or weakens, it can be preliminarily judged that there may be a mobile phone jammer working nearby.
Multiple attempts to connect: Repeatedly try to make a call or send a text message. If multiple attempts fail and the problem of the mobile phone and the operator is ruled out, it may be that the mobile phone jammer is interfering.
Abnormal signal fluctuation: If the mobile phone signal strength continues to fluctuate abnormally, it may be interfered by the jammer.
2. Use professional detection equipment
Spectrum analyzer: A spectrum analyzer can detect the strength of radio signals within a specific frequency band. If an abnormally strong signal is detected within the mobile phone frequency band, it may be that the mobile phone jammer is working.
Signal detector: A dedicated signal detector can scan and detect sources of radio signal interference to help confirm the location and working status of the jammer.
Radio interference detector: This device can detect radio interference signals within a specific frequency range to help confirm whether a mobile phone jammer exists.
3. Use services provided by mobile operators
Network diagnostic tools: Some mobile operators provide network diagnostic tools that users can use to detect mobile phone signal problems. If the test results show signal interference, it may be caused by a mobile phone jammer.
Carrier customer service support: Contact the carrier customer service to report the signal problem. The carrier can use technical means to detect and confirm whether there is external signal interference.
Detecting the presence of a mobile phone jammer is a highly technical task that requires a combination of the mobile phone’s own status, professional detection equipment, and carrier services. Through scientific methods and reasonable steps, the presence and working status of the mobile phone jammer can be effectively detected and confirmed. At the same time, pay attention to legal and compliant operations to protect your rights and interests. Whether in daily life or special occasions, understanding and mastering these detection methods can help us better deal with mobile phone signal interference problems.

A mobile phone signal jammer is a device used to interfere with or block wireless communication signals. It interferes with the communication between the mobile phone and the base station by emitting electromagnetic waves of the same frequency as the mobile phone signal, so that the mobile phone cannot receive or send signals normally within a certain range. This article will introduce the effective range of the mobile phone signal jammer and its influencing factors in detail to help readers better understand and use such devices.

Definition of effective range
The effective range of a mobile phone signal jammer refers to the maximum distance within its effective area that can effectively shield the mobile phone signal. This range is usually expressed in meters (m) and varies depending on the device model, power and usage environment.

Factors affecting the effective range
Power output

High-power jammers: These devices usually have a larger effective range and can cover distances of tens or even hundreds of meters. They are suitable for large venues such as conference centers, prisons and examination rooms.

Low-power jammers: Suitable for small venues such as offices, conference rooms or personal spaces, the effective range is usually between a few meters and more than ten meters.
Frequency coverage

Different mobile phone signals (such as 2G, 3G, 4G, 5G) use different frequencies, and the jammer needs to cover the corresponding frequencies to effectively shield the signal. Some multi-band jammers can block signals of multiple frequencies at the same time, providing a wider range of shielding within the same range.
Physical Obstacles

Walls and Building Structures: Signal shielding effectiveness is affected by physical obstacles such as walls, ceilings, and floors. Thick walls and metal structures can significantly reduce the propagation of the shielded signal, reducing the effective range.
Furniture and Equipment: Large furniture and electronic equipment can also block the shielded signal, reducing its effective range.
Environmental Interference

Electromagnetic Interference: Electromagnetic waves emitted by other electronic devices can interfere with the operation of the jammer, reducing its effective range.
Signal Strength: The effective range of the jammer is reduced in areas of high signal strength because a stronger interference signal is required to cover the original signal.
Mounting Position

cell phone jammer

Central Position: Placing the jammer in the center of the area to be shielded can maximize its coverage.
Height and Angle: Proper mounting height and emission angle can also affect the shielding effect. Usually, mounting it at a higher position can reduce the impact of obstacles and improve coverage.
Effective Range in Practical Applications
Meeting Rooms and Offices

In this environment, low-power jammers are usually sufficient, with an effective range of 5-20 meters, which can cover a standard-sized meeting room or office.
Examination room

To ensure the fairness of the exam and prevent cheating, examination rooms usually use medium-to-high power jammers with an effective range of 20-50 meters, covering the entire examination area.
Prisons and detention centers

These places need to shield signals in a larger range to prevent prisoners from illegally communicating. The effective range of high-power jammers can exceed 100 meters, depending on the specific situation.
Cinemas and theaters

In order to provide a quiet viewing environment, the effective range of the jammer is usually 10-30 meters, which can cover the entire audience area and avoid mobile phone ringing and communication interference.
Hospitals

The use of jammers in medical environments requires caution to avoid interference with medical equipment. The effective range is usually controlled to 10-20 meters to ensure that signals are only blocked in necessary areas.
Choosing the right jammer
When choosing a mobile phone signal jammer, you need to consider multiple factors to ensure that its effective range meets specific needs:

Requirements analysis

Clarify the size of the area and signal type that needs to be shielded, and choose the right device based on actual needs.
Power and frequency

Choose a jammer with appropriate power and frequency coverage to ensure that all required signal types can be blocked.
Installation and debugging

Install the jammer reasonably to ensure that it is in the best position to achieve the maximum effect. Debug it according to the environment and usage to optimize the shielding effect.
Regulations and safety

Ensure that the device complies with local laws and regulations to avoid illegal use. At the same time, pay attention to the safety of the jammer to avoid adverse effects on human health and other equipment.
Summary
The effective range of the mobile phone signal jammer depends on many factors, including device power, frequency coverage, physical obstacles, environmental interference, and installation location. Understanding these factors helps to select and use the appropriate jammer to meet the needs of specific scenarios. Jammers are widely used in various environments, from small offices to large examination rooms and prisons, but they should be used with caution and comply with relevant laws and regulations to ensure legal and safe operation. By reasonably selecting and using jammers, wireless communications can be effectively controlled, information security can be protected, and order in specific places can be maintained.

How to install and use a mobile phone signal jammer? 1000-word copywriting
ChatGPT
A mobile phone signal jammer is a device used to interfere with or block wireless communication signals. Proper installation and use of a mobile phone signal jammer can effectively ensure information security and order in specific places. The following is a detailed installation and usage guide.

Preparation before installation
Clear requirements

Target area: Determine the specific area where the signal needs to be shielded, such as conference rooms, examination rooms, cinemas, etc.
Signal type: Understand the type of signal that needs to be shielded (such as GSM, 3G, 4G, 5G, Wi-Fi, etc.) to select a suitable shielding device.
Equipment selection

Frequency coverage: Select a shielding device that can cover the target signal frequency band.
Power: Select a shielding device with appropriate power according to the size of the target area. Low-power shielding devices can be selected for small areas, while high-power devices are required for large areas.
Brand and certification: Choose reputable brands and certified products to ensure equipment quality and safety.
Legality check

Before purchasing and using, make sure to understand and comply with local laws and regulations on mobile phone signal shielding devices to avoid illegal use.
Installation steps
Choose the installation location

Central location: Install the shielding device in the center of the area to be shielded to maximize coverage.
Height: Installing it in a higher position (such as the ceiling) can reduce the impact of obstacles and improve the shielding effect.

A WiFi signal jammer is a device that blocks WiFi communications by emitting interference signals. Its working principle is based on radio frequency interference technology, which interferes with the communication between the device and the wireless network, causing the network connection to be interrupted or invalid. This device has aroused widespread concern and controversy in the modern wireless communication environment, and understanding its working mechanism is of great significance for us to deal with potential network interference. cell phone jammer

Basic principles of wireless communication
Before discussing WiFi signal jammers, we need to understand the basic working principles of WiFi networks. WiFi (Wireless Fidelity) is a technology that allows devices to communicate through radio waves. It mainly uses the 2.4 GHz and 5 GHz frequency bands to transmit Internet signals to connected devices such as computers, mobile phones and smart home devices through routers.

The communication process of WiFi networks is as follows:
Data transmission: The router converts Internet data into radio signals and sends them around through antennas.
Signal reception: The WiFi receiver on the device receives these signals and converts them back into data.
Feedback loop: The device transmits the data requested by the user back to the router to complete the two-way communication.
How WiFi signal jammers work  signal jammer
WiFi signal jammers block communications by emitting powerful radio signals that interfere with and drown out the signals of legitimate WiFi networks. Its working principle mainly includes the following aspects:

Frequency interference: WiFi signal jammers transmit radio signals in the same frequency band as WiFi networks (i.e. 2.4 GHz or 5 GHz). Due to the high intensity of the interference signal, the legitimate WiFi signal is drowned out and the device cannot receive a clear signal, resulting in communication interruption.
Signal blocking: The jammer continuously transmits random or specific pattern signals, blocking the channels of legitimate WiFi networks, making it impossible for wireless devices to communicate normally on the designated channels.
Destroy synchronization: WiFi networks rely on time synchronization between sending and receiving devices. The jammer destroys this synchronization by transmitting interference signals, making it impossible for the device to correctly decode and process data packets, resulting in network connection failure.

A cellular jammer is a device designed to block cell phone communications. As the number of mobile phone users around the world continues to increase, almost everyone has one or more mobile phones, and these devices are used for different purposes. However, the widespread use of mobile phones has also brought about issues such as privacy violations and inconvenience in public places, so it is particularly important to understand how cellular jammers work and their impact.

How jammers work
Cellular cell phone jammers block cell phone communications with base stations by sending out shielding signals. These shielding signals are the same frequencies used by mobile phones, thus interfering with normal communication between the mobile phone and the base station, making the mobile phone unable to receive the base station signal, causing communication interruption. When a jammer is operating within a certain area, cell phone users may find that their device’s signal becomes very weak or even loses signal entirely. However, this interference is difficult to detect because the phone will simply show a poor signal.

Place of use and legality
Although the use of cellular signal jammers is prohibited by law in most countries, their use is relatively common in public places such as schools, theaters and restaurants. This is because managers in these places hope to maintain quiet and order by blocking cell phone signals. Mobile phone companies encourage mobile phone etiquette education to solve the problem, but many places still choose to use jammers to directly prevent mobile phone use.

In the United States, the Federal Communications Commission (FCC) has control over broadcast public telecommunications services. Telecommunications companies pay to lease specific frequency ranges, and interfering with these frequencies can harm service reliability and is considered illegal. Blocking a signal does more than hinder communications and may be considered property theft. Additionally, more than 100,000 emergency 911 calls are made from cell phones every day, so using jammers could impede emergency calls with serious consequences.

Legal and ethical issues
In the United States, the use of jammers is illegal and is considered interference with authorized telecommunications services and may even be considered theft. Therefore, people using jammers must be aware that they are breaking the law. Not only does this lead to legal trouble, but it also poses a potential threat to public safety. For example, the indiscriminate operation of jammers could block emergency calls, causing serious safety concerns.

Specific use cases and social impact

In some specific places, such as schools, theaters and restaurants, managers hope to create an environment free of cell phone interference by using jammers. Managers at these places believe that disruptors can help maintain order and quiet, ensuring students are focused on learning, audiences are attentive to performances, and patrons are enjoying their dining experience. However, this approach has also brought controversy. While jammers can prevent unnecessary cell phone use, they can also block important communications during emergencies.

For example, in schools, while using jammers can prevent students from using cell phones in class, students and staff may not be able to communicate in a timely manner via cell phones during an emergency. In addition, in theaters and restaurants, while jammers can prevent cell phones from disturbing others, they may also block emergency calls, posing a potential safety hazard.

Legal requirements and risks
Using cellular jammers is illegal in most countries, including the United States. These laws are designed to protect the public’s communications rights and public safety. The use of jammers is considered interference with authorized telecommunications services and is not only a violation of communications regulations but may also be considered an act of theft. In the United States, the Federal Communications Commission (FCC) has very strict controls over public telecommunications services, and unauthorized signal interference will result in severe penalties.

In addition, the use of jammers can lead to legal disputes and public safety issues. Indiscriminate blocking by jammers may result in inability to seek help in time in an emergency, leading to serious consequences. Therefore, when using jammers, great care must be taken to ensure that legal provisions are not violated and that public safety and individual communications rights are taken into account.

Summarize
Cellular jammers block communications between cell phones and base stations by sending a shielded signal in the same frequency range as the cell phone. However, due to their indiscriminate blocking and difficult-to-detect characteristics, using jammers in public spaces can create legal and safety issues. Although the law prohibits the use of jammers in most situations, some places still choose to use them to maintain order.

In order to balance the convenience brought by mobile phone use with the possible interference, mobile phone companies advocate solving the problem through mobile phone etiquette education. This will not only reduce unnecessary cell phone use, but also safeguard personal communication rights and public safety. In summary, cellular jammers can play a role in certain circumstances, but their use must comply with legal and ethical regulations to ensure that they do not adversely affect public safety and personal rights.

Security monitoring has become one of the most important components of our security work. From front-end high-definition cameras to network transmission monitoring, to back-end storage and high-definition video display, the increase in investment costs alone is enough to explain the importance of video surveillance in the entire security project. However, in the daily use of the monitoring system, there are often some interferences that prevent the monitoring system from working properly. So is there any way to eliminate these interferences? Let’s talk about some of the “most” interference removal methods.

1. The most common: wood grain interference   signal jammer
In daily use, wood grain interference is one of the most common interferences. There are many reasons for this interference, the most common of which is defects in the video transmission cable. In addition to problems with the line itself, wood grain interference is sometimes caused by strong current interference near the transmission line. Of course, to deal with current interference, you only need to use purified power supply or online power supply in the entire system. Regarding this problem, the solution is to strengthen the shielding of the front-end equipment, or ground the video cable.

2. Maximum area: reticulated interference
In addition to wood grain interference, there is also mesh interference that may occasionally affect visual viewing. Among common interference images, the area affected by pattern interference should be considered the largest. Although the interference area is large, the processing is not as “domineering” as it seems.

Regarding the origin of this interference, it is usually caused by a small short circuit or open circuit between the transmission core of the video cable and the surrounding protection network. Therefore, this problem often occurs with BNC connectors or many other types of connectors. The solution is to check the corresponding connectors one by one and replace the problem equipment in time, so you can easily get rid of the confusion of this kind of interference.

3. The most organized: vertical bar interference
Although this type of interference is uncommon, its characteristics are very obvious. The main reason for the formation of vertical bar interference is that the quality of the cable does not meet the specifications, resulting in abnormal associated data during the transmission process. Therefore, when dealing with this kind of interference situation, the method of “connecting a resistor in series at the beginning” or “connecting a resistor in parallel at the terminal” can be used. Of course, the best way to prevent this kind of interference is to strictly control product quality during the wiring process.

From 1994 to 1998, many actual tests were conducted on “Big Brother”, “Second Brother”, walkie-talkies and other mobile phones. The actual measurement methods used the simulation comparison method and the simulation method. The test results are now listed in Table 5-1.   signal jammer
The actual measurement results show that the radiation field strength of different types of mobile phones produced by different manufacturers has certain differences. Generally speaking: the electromagnetic radiation field strength of “Big Brother” is about several hundred μw/c㎡; The electromagnetic radiation field strength is about several thousand μw/c㎡; the radiation field strength of the walkie-talkie is about 1-4 thousand μw/c㎡.
Through multiple organized measurements of the incoming field strength of electromagnetic radiation from mobile phones, it can be seen that a considerable proportion of mobile phones that have been put into use have excessively high radiation levels. According to my country’s international GB10436-89 hygiene standard for microwave radiation in workplaces: the average power density of continuous wave exposure for 8 hours a day is 50 microwatts/cm2; GB9175-88 hygiene standard for environmental electromagnetic waves: the allowable microwave field strength (middle zone) is For evaluations of less than 40 microwatts/cm2, 65~70% exceed the standard.

The huge increase in mobile phone users has brought about some unexpected serious consequences: using mobile phones while flying can interfere with the aircraft’s navigation system and cause plane crashes; using mobile phones in hospitals can interfere with hospital ECG monitors, hemodialysis machines, and automatic injection machines. The normal operation of medical equipment such as heart pacemakers and pacemakers can put patients’ lives in danger; using mobile phones at gas stations interferes with technical systems and even causes fires… The tragedies caused by improper use of mobile phones are shocking enough.
The radiation interfered with the pacemaker, and a life was almost lost while talking on the phone.
According to the Beijing Evening News Guangzhou Special News on the morning of August 24, a patient in Guangzhou with a permanent pacemaker was almost “killed” by a mobile phone.
The patient surnamed Wang went to the hospital to have a permanent pacemaker installed because of bradycardia the year before last. <Year> At 9 a.m. on August 24, after he borrowed a friend’s cell phone and made a call for a while, he suddenly felt his heart beat fast and slow, and his face changed drastically. His friend quickly escorted him to a nearby hospital for treatment. After examination by the doctor, it was determined that the radiation from the mobile phone was to blame. The doctor explained that electromagnetic radiation from radio electronic equipment can interfere with the control signals of medical equipment and instruments, disrupting their normal operation. When a patient with a pacemaker uses a mobile phone, pager or program-controlled telephone; or when he or she stays near a small mobile communication device such as a mobile phone or pager, his or her heart rate may slow down or stop, which may be life-threatening.
Therefore, patients with pacemakers must try to stay away from mobile communication devices and household appliances such as mobile phones, pagers, digital program-controlled phones, microwave ovens, and induction cookers. For the sake of safety, people with pacemakers can wear effective electromagnetic shielding clothing, such as shielding shirts, coats, vests, etc.

With the popularization of 5G technology, the application of mobile phone signal jammers in certain specific occasions has gradually increased. 5G signal jammer, as the name suggests, is a device specially used to shield 5G signals. Its main purpose is to prevent mobile phone signals from interfering with specific occasions and protect privacy and security. However, does the use of 5G signal jammers really bring safety protection, or is there more hidden dangers? This article will explore this issue from multiple aspects.

The functions and advantages of 5G signal jammers
First of all, the application of 5G signal jammers in certain specific situations has obvious advantages. In conference rooms, examination rooms, hospitals and other places, interference from mobile phone signals often causes a lot of inconvenience. For example, during important meetings, cell phone ringtones and information notifications not only interrupt the meeting process, but may also lead to the leakage of sensitive information. 5G signal jammer can effectively prevent these problems by blocking mobile phone signals, ensuring the smooth progress of meetings and the security of information.

In the examination room, the use of mobile phones may also lead to cheating. 5G signal jammers can effectively block candidates’ mobile phone signals, thereby preventing candidates from cheating through their mobile phones and ensuring the fairness of the exam. In addition, medical equipment in hospitals is very sensitive to wireless signals. 5G signal jammers can prevent mobile phone signals from interfering with the normal work of medical equipment and ensure patient safety.

Hidden dangers and risks of 5G signal jammers
5G signal jammers are not without pitfalls and risks. The first is the legal risk. Many countries and regions have strict regulations on the use of signal jammers. Using signal jammers without permission may violate the law and lead to legal disputes. Even in some countries, the use of signal jammers is completely illegal, so users need to fully understand local laws and regulations before use to avoid legal risks.

5G signal jammers may cause interference to other wireless devices. Although its main purpose is to block mobile phone signals, in actual operation, it is difficult to block only signals in specific frequency bands. Some wireless networks, Bluetooth devices, and even wireless surveillance equipment may also be affected by interference, causing these devices to not work properly. This will not only affect work and life, but may also bring safety hazards. For example, in an emergency, if the communication equipment of first responders is interfered with by a signal jammer, it may delay rescue time and cause serious consequences.

Faraday bags, no matter how effective they are, can only block radio communications. Cell phones can do malicious things that don’t involve using radios.

Modern mobile phones have become highly complex, with a large amount of delicate electronic hardware controlled almost entirely by microprocessors and software. While this is good news for functionality, it is bad news for security. For devices such as smartphones, the software controls almost everything about the phone, including how and when to turn the power on and off. In other words, the phone “has its own ideas”, including understanding “shutdown”.  signal jammer

The complex software systems of mobile phones are, to put it mildly, largely beyond the control of the user, especially in the case of smartphones equipped with microphones, cameras, location and environmental sensors, and communication links, and bugs in the software that controls them (or backdoors) and security vulnerabilities can have severe privacy implications.

It’s hard for people to reliably turn off software-based devices like smartphones completely, and this isn’t a persecuted fantasy, and some phone manufacturers even consider it a thoughtful feature. For example, some Apple iPhones continue to send Find My Device tracking beacons even when they are turned off. Even on devices that don’t “officially” support this feature, it’s possible for bad actors or malware to behave similarly, turning your phone into a permanent covert tracking device, regardless of whether you’ve turned it “off.” The risk of “false shutdown” is compounded by the non-removable batteries in many of the latest smartphones.

A well-known and popular method for those who want to ensure that their phone is isolated in certain scenarios and completely block the phone’s radio (including sending and receiving cell tower information, wifi, Bluetooth and NFC near-field communications, and GPS positioning signals) is to The phone was thrown into something called a “Faraday bag.”

The Faraday cage effect produced by Faraday bags can severely weaken or even block the radio signals of the devices inside, and is widely used to ensure that untrusted devices (such as mobile phones) can send and receive signals in unknowing or inappropriate scenarios. The principle of a Faraday cage is simple: it is just a solid conductive container that completely encloses the signal source, so that the RF voltage difference between any two points on the cage is always zero.

But in reality, building a Faraday cage system that works well in practice is not as simple as it seems. Any poorly sealed opening can create a junction that acts as an RF feed and significantly reduces attenuation efficiency.

Currently, some expensive (usually around a few hundred yuan) so-called commercial Faraday bags are hotly sold on e-commerce platforms. They are specially used for mobile phones and can be used to prevent commercial espionage or “pregnant women to protect themselves from radiation.” In addition, there are also a large number of claims on the Internet that claim to be able to temporarily shield The “local method” of mobile phone signal.