A mobile phone signal jammer is a device that can emit electromagnetic waves of a specific frequency to cover or block mobile phone signals. Its working principle is based on sending signals of the same frequency as the base station to the mobile phone, thereby drowning out the signals received by the mobile phone from the base station, making it unable to make calls, send text messages, or use mobile data services normally. This type of device is usually used in places where the use of mobile phones needs to be restricted or prohibited to achieve the various purposes mentioned above.

There are various types of mobile signal jammers, which can be divided into two categories based on the interference range: small handheld and large fixed. Handheld jammers are easy to carry and have a small interference range, usually used for personal privacy protection or signal blocking within a small range; Large fixed jammers are installed in specific locations, such as prisons, schools, and other places, with a large interference range that can cover the entire area.

It mainly has the following functions:

1. Privacy protection: In highly confidential situations such as meeting rooms, examination rooms, etc., using signal jammers can prevent mobile phone calls and information transmission, and protect meeting content or exam questions from being leaked.

2. Security maintenance: In sensitive areas such as prisons and military facilities, mobile signal jammers can prevent prisoners or illegal individuals from using their phones for communication, maintaining the safety and stability of the premises.

3. Reduce interference: In certain specific situations, such as hospital operating rooms and aircraft takeoff and landing processes, mobile phone signals may interfere with the normal operation of medical equipment or navigation systems. The use of signal jammers can eliminate this interference.

4. Time management: In some situations that require strict adherence to schedules, such as theaters and cinemas, mobile signal jammers can reduce audience behavior of answering and making calls during performances, improving the audience experience.

5. Forced rest: In certain activities that require prolonged concentration, such as meditation classes and yoga exercises, mobile signal jammers can help participants reduce distractions and better engage in the activity.

It should be noted that the use of mobile signal jammers is legally restricted in many countries and regions, as it may affect emergency communication and public safety. Therefore, it is necessary to ensure compliance with local laws and regulations before use.