Many users who use cellphone wifi jammer do not understand the principle of operation and often exceed the frequency range when using it, resulting in poor usage.
The working principle of mobile communication is that wireless devices (cell phones, etc.) communicate with the base station via radio waves within a certain frequency range and complete the data and sound transmission with a certain baud rate and modulation method. The mobile phone communicates with the base station via the uplink frequency and then transmits the signal to the exchange of the cellular service in order to make the call. In the standby state, the mobile phone communicates with the base station via the broadcast control channel. Once there is a call request, it is assigned to the cellular service channel according to the specific conditions of the channel near the terminal by 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 be able to receive and terminate the communication effectively.
According to the above working principle, the cell phone signal jamming transmitter generally consists of a power supply unit, an electronic scanning control unit, a segmented high-frequency module unit, an amplifier unit, a transmitting antenna unit and other parts. The sampling signal generated by the signal generator passes through the inverter, enters the oscillator and modulates it in the working frequency band of mobile communications, and is then 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. Since the frequency sweep signal forms garbled interference in the message signal received by the cell phone (increasing the amount of noise and noise in the device threshold), the cell phone cannot receive the normal data sent from the base station, so the cell phone cannot connect normally with the base station, whereby the mobile phone separates the communication network of the base station. The mobile phone has the phenomenon that there is no signal and no service system in the search network, thereby achieving the blocking effect.
The interference power of the jammer is fixed and the shielding radius of the free space is determined by the path attenuation and the signal level of the receiving base station. In order to realize interference from cell phone signal jammers to cell phone networks, it must be ensured that the signal field emitted by the jammer is stronger than that of the cell phone signal in the interference range. The closer the interference location is to the base station, the stronger the field strength and the smaller the effective interference range. The further away 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 area depends on the field strength in the interference area. Regardless of how strong the jammer is, the jamming signal strength is gradually attenuated and loses the ability to interfere as long as the transmit power is a fixed value and the distance increases.