On the problem of mobile phone signal shielding device

The shielding instrument used in the examination room has no other function, that is, it interferes with the work of communication equipment in fixed frequency band. Some examination rooms will be equipped with vehicle-mounted signal monitoring equipment for arresting criminal suspects through corresponding handheld terminals. But this kind of vehicle-mounted equipment can't be called shielding instrument.

There is no equipment to disable the signal jammer. However, some devices can communicate using undeclared communication frequency bands, which are usually not interfered by signal jammers. I mentioned the specific principle and background when answering other people's questions, and I posted it directly:

The principle of ordinary microwave communication equipment is to apply for a special communication frequency band in ITU, and then use a bandpass filter to filter out signals outside its own frequency band. This is the communication between the mobile phone and the base station. The communication function of the mobile phone is realized by establishing a microwave network between the mobile phone and the base station and a cellular network between the base stations. Since each communication has its own frequency band, the filter will filter the signals except its own frequency band, so communication devices usually do not interfere with each other.

Shielding instruments are different. Shielding instrument will send a lot of interference signals in common communication frequency bands, such as China Unicom and mobile phone frequency bands. These signals will cause the base stations within this range to be unable to receive the coded signals sent by normal terminals (mobile phones). There is no signal on the mobile phone, because the principle of the strength of the mobile phone signal is to send a service request to the base station every once in a while, indicating that the service is needed, and the base station sends a reply, indicating that the service is provided. The proportion of the received and lost reply of the mobile phone is converted into the number of your mobile phone signals. The so-called cell phone signal under the jammer is displayed as 0 grid, which means that all the request signals sent by you are interfered by garbled codes, and the communication between the cell phone and the base station is completely interrupted.

The new cheating device that was seized before is to connect two terminal devices directly by microwave, and complete communication in the frequency band not reported by ITU. Shielding instruments will naturally not interfere with this frequency band. Even in order to avoid discovering and shielding new frequency bands and prevent devices from interfering with each other because they use the same frequency band (that is, crosstalk, all receiving devices using this frequency band receive the information of all transmitting devices), in fact, devices that can communicate in the 10 frequency band were found in cheating gangs uncovered last year.

My current short-term project is to develop a screening device for this year's examination room for a provincial education department to interfere with the found cheating frequency band. The long-term project is to develop a three-core autonomous sniffer screening instrument based on XXX, XXX and XXX. Theoretically, the current communication equipment should be completely shielded, and it is easy to locate suspects. There should be some time between now and the completion of research and development and large-scale use. If it is a device that just came out this year and uses the new frequency band to communicate, the shielding instrument should still be difficult to play its role. If it is legal to obtain signals in places with shielding devices, it is suggested that you contact relevant communication experts to keep the communication equipment in a frequency band that is not interfered by shielding devices. In addition, according to international law and relevant documents, you need to apply for using this frequency band in ITU.

The above information is provided by me free of charge, for learning and communication purposes only, and shall not be used for commercial or illegal purposes. I hereby declare that the legal consequences arising therefrom have nothing to do with me.