The working principle of mobile communication is that within a certain frequency range, wireless devices (mobile phones, etc.) and base stations communicate through radio waves to complete data and sound transmission with a certain baud rate and modulation method. When the mobile phone communicates, it contacts 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 need for a call, the mobile phone will first be assigned to the mobile phone business channel according to the specific conditions of the channel near the terminal, so that the mobile phone can jump to the business channel to realize the call and data transmission. . At the same time, wireless communication must ensure a sufficient signal-to-noise ratio to effectively receive and complete the communication.
According to the above working principle, the wifi signal jammer is generally composed of a power supply, an electronic scanning control unit, a segmented radio frequency module unit, an amplifier unit, and a transmitting antenna unit. After the signal generator generates a scanning signal and passes through the inverter, it enters the oscillator to be modulated to the mobile communication working frequency band, and then is amplified by a power amplifier and a voltage regulator tube to control 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 (increase the ratio of the noise signal to the device threshold), the mobile phone cannot receive the normal data sent by the base station, so that the mobile phone cannot establish a normal connection with the base station, so that the mobile phone is disconnected. Base station communication network. The mobile phone shows the phenomenon of no signal and no service system in the search network, so as to achieve the blocking effect.
The working principle of the signal jammer is to scan from the low-end frequency of the forward channel to the high-end frequency at a certain speed during the working process. The scanning speed can cause garbled interference in the received message signal of the mobile phone. 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, so as to achieve the purpose of shielding the mobile phone signal. No service system, etc.
The interference power of the wireless wifi bluetooth jammer is fixed, and the shielding radius of the unobstructed space is determined by the path attenuation and the signal level of the receiving base station. To realize the interference of the mobile phone signal jammer to the mobile network, it must be ensured that the signal field emitted by the jammer is stronger than the field strength of the mobile signal in 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, and vice versa. , the farther the interference site 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 wifi 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 table below provides a comparison table of distance and path attenuation. The theoretical coverage radius with reference value can be determined by the output channel power of the masker, the signal level of the base station, and the gain of the coverage line.