The working principle of mobile communication is that within a certain frequency range, the mobile phone jammer and the base station communicate through radio waves, and complete the transmission of data and sound with a certain baud rate and modulation method. When the mobile phone communicates, it communicates with the base station through the uplink frequency, and then transfers the signal to the mobile service switching center to realize the call. In the standby state, the mobile phone communicates with the base station through the broadcast control channel. Once there is a call demand, it will be allocated to the mobile phone service channel according to the specific conditions of the channel near the terminal through the request, so that the mobile phone can jump to the service channel to realize the call and data transmission . At the same time, wireless communication must ensure a sufficient signal-to-noise ratio in order to receive effectively and complete the communication.
According to the above working principle, the mobile cell phone signal jammer is generally composed of power supply, electronic scanning control unit, segmented radio frequency module unit, amplifier unit, transmitting antenna unit and other parts. The scanning signal generated by the signal generator passes through the inverter, enters the oscillator and modulates it to the mobile communication working frequency band, and then is amplified by the power amplifier and the voltage regulator tube controls the power. The amplified frequency sweep signal is transmitted into the air in the form of radio waves. Because the frequency sweep signal forms garbled interference in the message signal received by the mobile phone (increasing the proportion of noise and noise signals to the device threshold), the mobile phone cannot receive the normal data sent by the base station, which prevents the mobile phone from establishing a normal connection with the base station, thereby causing the mobile phone to disconnect Base station communication network. The mobile phone exhibits the phenomenon of no signal and no service system in the search network, which achieves the blocking effect.
The interference power of the mobile phone signal jammer is fixed, and the shielding radius of the unblocked space is determined by the path attenuation and the signal level of the receiving base station. To realize interference from mobile phone signal jammers to mobile networks, it is necessary to ensure that the signal field emitted by the mobile phone signal jammer is stronger than the mobile signal field strength of the interference area. The closer the interference location is to the base station, the stronger the field strength and the smaller the effective interference area. On the contrary, the farther the interference location is from the base station, the weaker the field strength and the larger the effective interference area.
It can be seen that within a certain transmission power, the interference range depends on the field strength in the interference area. No matter how powerful the mobile phone signal jammer is, as long as the transmission power is a fixed value, as the distance increases, the interference signal strength will gradually attenuate , Thereby losing the ability to interfere. The following table shows the comparison table of distance and path attenuation. Then the output channel power of the mobile phone jammer, the signal level of the base station, and the coverage line gain can determine the theoretical coverage radius with reference value.