There have always been malpractices in school exams. With the development of technology, mobile phones can do more and more things. This has become an increasingly important issue for the education sector. In order to ensure the safety of examination information, some ordinary colleges and universities usually use frequency jammers to interfere with external signals within a certain range. Today, I will talk about the working principle of mobile phone signal jammers and how they interfere with mobile phone signals.

So, what is a jammer? Let's first understand what is a jammer, also known as a frequency jammer. Its working principle is to implement the same frequency electromagnetic interference to the wireless network on which mobile communication depends, so that the mobile network can not communicate normally, so as to achieve the purpose of interference. Therefore, the frequency jammer only interferes with the mobile phone signal and will not affect other electronic devices. It should be noted that in order to realize the interference of the jammer to the mobile network, it must be ensured that the signal field strength sent by the jammer is far greater than the field strength of the mobile signal BCH in the interference area. The closer the interference location is to the base station, the stronger the BCH field strength is, and the smaller the effective interference area is. The mobile phone communicates with the base station through the uplink frequency, and then transfers the signal to the MSC (Mobile Service Switching Center) to make calls. In standby mode, the mobile phone contacts the BTS through the BCH broadcast control channel. Once there is a call demand, first ask the MSC through the BCH. The MSC allocates the mobile phone service channel according to the channel status, so that the mobile phone can jump from the BCH to the service channel to make calls.