Generally speaking, these "black technology" cheating methods, regardless of the principle, cannot avoid requiring candidates to send and receive information in the examination room, and both of them need to be performed in places with signals.

Therefore, in view of this feature, the main way of anti-cheating is to equip with an examination signal shielding device, which can directly shield all electronic signals in the range from the root. In the face of this practice, no matter what kind of black technology, it is unstoppable and the scope is very considerable.

Although there will be some differences according to different models and products, the general standard is a radius of 0 to 20 meters. It is necessary for colleges and universities to choose the test signal shielding device as a means to deal with cheating by using electronic signals.

Extended data

Brief introduction of mobile communication principle;

The working principle of mobile phone is that in a certain frequency range, mobile phone and base station are connected by radio waves, and data and sound are transmitted at a certain baud rate and modulation mode.

Brief introduction of the principle of mobile phone signal shielding device (shielding instrument);

According to the above communication principle, the shielding body scans from the low-end frequency to the high-end frequency of the forward channel at a certain speed during operation. This scanning speed will cause garbled interference to the message signal received by the mobile phone, and the mobile phone can't detect the normal data sent by the base station, which leads to the failure of the mobile phone to establish a connection with the base station. Mobile phones are characterized by searching the Internet, no signal and no service system.

Mobile phone signal shields are mainly used in examination rooms, schools, gas stations, churches, courts, libraries, conference centers (rooms), theaters, hospitals, governments, finance, prisons, public security, military places and other places where the use of mobile phones is prohibited.

Baidu encyclopedia-signal shielding