2022.06.29- After the mobile phone jammer is installed in the classroom, the effect of jamming the  phone is not good. It turned out that the indoor signal distribution system was installed covertly.

One day, I was surveying the site environment for a school. In a classroom that was going to be used as an examination room, I tested the actual effect of jamming the  phone after turning on the mobile phone jammer. It was found that the effect of jamming the  phone was very unsatisfactory. According to the observation results of many mobile phones on site, the mobile phones of China Telecom and China Unicom were completely interfered, and the mobile phones of China Mobile can only be interfered within 2-3 meters away from the mobile phone jammer.

In response to the results of such an initial test, we used a spectrum analyzer to detect and analyze the on-site environment, and soon found that there is a strong mobile phone base station signal in the 2300-2400MHz frequency band, which is the most typical indoor signal distribution system. Common frequency band used. So we pointed out to the school that the indoor signal distribution system of the communication operator must be installed in the classroom corridor. It is also very simple, the purpose of our mobile phone jammer is to interfere with the mobile phone signal, while the purpose of the indoor signal distribution system is just the opposite, it is to strengthen the strength of the mobile phone signal. One is desperately trying to interfere and suppress normal signals, while the other is desperately amplifying and spreading the signal of the mobile phone base station. There is a natural opposition between the two.
At first, when we asked the question, the teachers of the school did not believe what we described at first, saying how could there be a room distribution system of a communication operator installed in the teaching building? In fact, this is just because the teacher usually doesn't notice that these room systems are hidden in the ceiling of the corridor, and no one will find out if the ceiling is not opened.

Therefore, we randomly selected two ceilings above the door of the classroom. Fortunately, this is the antenna installation location of an indoor signal distribution system, and it is obvious that there is not only one operator here. Commercial and indoor distribution systems of multiple operators are concentrated here.

The reason why the mobile phone jammer is not effective in interfering with the mobile phone has been found, so we proposed a solution to the school: in such an environment, if you want the mobile phone jammer to perform fully and normally, a The equipment can ensure complete interference in a classroom. The best way is to temporarily turn off the indoor signal distribution system while the mobile phone jammer is turned on and used.