The working principle of mobile phone signal jammer:

In a certain frequency range, the mobile phone and the base station are connected by radio waves, and the data and sound are transmitted at a certain baud rate and modulation mode. The shield scans from the low-end frequency of the forward channel to the high-end at a certain speed during operation. The scanning speed can form garbled interference in the 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, and the purpose of shielding the mobile phone signal is achieved, and the mobile phone is displayed as a search network, no signal, No service system and other phenomena.

Generally speaking: when the mobile phone signal shielding device works, it will issue a frequency to interfere with the downlink signal of its base station. If the power of the shielding device is greater than the power of the local base station signal, then the mobile phone will have no signal if the power of the shielding device is less than the local power. The power handset of the base station signal will have a signal.