Mobile phone signal communication and interference principle

Communication principle: within a certain frequency range, the mobile phone segment and the base station are connected by radio, and the data, voice, text, image and other electrical signals needed to be transmitted are modulated on the radio wave and transmitted to the other party through space or ground. The coverage of the signal base station is limited. If you are just at the edge of the coverage, there will be signal attenuation.

Signal shielding principle: When the mobile phone signal shielding is working, it sends out interference signals to interfere with the channel frequency band of the base station. The interference signals increase the error rate of the channel, reduce the signal-to-noise ratio of the channel, and make the mobile phone unable to decode the information sent by the base station normally, thus making the mobile phone unable to establish a normal connection with the base station. When the mobile phone cannot determine its service area after many attempts, the mobile phone will display no signal, Search the network, not in the service area and other phenomena.

The signal shield also emits electromagnetic interference signals. The carrier frequency of this signal is the same as that of the base station signal. Therefore, it can form garbled interference when the mobile phone receives the signal. The mobile phone cannot detect which is the normal data sent by the base station and which is the interference signal, effectively blocking the normal operation of the mobile phone signal.