The principle of mobile phone (radio communication) is as follows: within a certain frequency range, the mobile phone and the base station are connected by radio waves, and the data and sound transmission is completed with a certain baud rate and modulation method. In view of the above communication principle, the Adafruit Cell Phone Jammer scans from the low-end frequency of the forward channel to the high-end at a certain speed during the working process. This scanning speed can cause garbled interference in the message signal received by the mobile phone, and the mobile phone cannot detect the normal data sent from the base station, so that the mobile phone cannot establish a connection with the base station. The mobile phone is manifested as a search network, no signal, no service system and other phenomena. cell phone jammer
Now the classrooms installed Adafruit Cell Phone Jammer are all full frequency bands, which can shield all the 2G 3G 4G signals, 2.4G WIFI signals and Bluetooth signals under the three operators of China Mobile, China Unicom and China Telecom. Some posts say that after turning off the automatic selection of the mobile phone network operator, it will not be blocked if the network is manually selected. In fact, this is not correct, because the mobile jammer is aimed at all mobile phone frequencies under the three operators. It is shielded, so no matter how it is switched, it will be shielded, which means that no matter what the mobile phone card is, it is within the shielding range of the shielding device. This cannot be evaded by cracking the number and band,
