With the development of society and the advancement of science and technology, almost every one of us has a mobile phone, and other wireless devices such as Bluetooth headsets and tablet computers are also widely popularized. So, how do wireless signals propagate and how are they shielded?
How wireless communication works
When a wireless communication device such as a mobile phone works, it communicates with the base station through radio waves within a certain frequency range, and completes 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 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 sufficient signal-to-noise ratio in order to effectively receive and complete the communication.
How Signal Jammers Work
According to the above working principle, the mobile phone 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 working frequency band of mobile communication, and then is amplified by the power amplifier and the voltage regulator tube controls the power. Because the frequency sweep signal forms garbled interference in the received message signal (increase the ratio of the noise signal to the equipment threshold), the normal data sent by the base station cannot be received, and a normal connection with the base station cannot be established, thus leaving the base station communication network. It is manifested in the phenomenon that the search network has no signal, no service system, etc., to achieve the blocking effect.
The interference power of the shield 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. In order to realize the interference of the wifi signal jammer to the mobile network, it must be ensured that the signal field strength sent 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. 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 shield is, as long as the transmission power is a fixed value, as the distance increases, the interference signal strength will gradually attenuate, thereby losing Interference ability.