The essence of the wireless wifi signal jammer is to implement electromagnetic interference to the wireless network on which mobile phone communication depends, so that the mobile phone cannot access the network, and thus cannot receive information from the mobile network, and cannot send information through the network. But it has no effect on the signal generated by the phone.
Signal jammers are mainly aimed at all kinds of examination rooms, schools, gas stations, churches, courts, libraries, conference centers (rooms), theaters, hospitals, governments, finance, prisons, public security, military centers and other places where the use of mobile phones is prohibited. It is understood that the wifi signal jammer on the market can limit the mobile phone signal beyond 500M meters from the transmitter, for example, the range radius of Jinyuda's P501 jammer is > 20 meters. The shielding radius can be adjusted, and the coverage can reach more than 30 square meters. The mobile phone signal blocker can only shield the mobile phone signal without affecting other electronic equipment. Save electricity, the power is 12W--480W.
Working principle
Use the sawtooth wave to control the voltage-controlled oscillator to generate a frequency sweep signal of the working frequency band. The pulse (caused by the reverse travel of the sawtooth wave) destroys the data exchange between the mobile phone and the base station in the coverage area. The mobile phone cannot get the base station data, and can only display no signal, and of course it cannot communicate.
The frequency of the sawtooth wave used in the measured CDMA frequency band is about 30KHz, and the frequency of the sawtooth wave used in the other three frequency bands is 10KHz. According to analysis, the sawtooth wave is not used for measurement here, but it can only make the voltage-controlled oscillator work, without any precision, it can be generated by a relatively simple circuit as shown in the figure below.
Circuit diagram
The circuit is simple, the components are easy to obtain, and the precision is not high, but it is enough to meet the requirements. Here, maybe a sawtooth wave with less precision and longer return would be better? Both the VCO and the RF amplifier have relatively high operating frequencies and have a lot in common.
Instructions:
1. Select the area where you want to cut off the cell phone signal, and place the cutter on the table or wall in this area.
2. After the installation is complete, turn on the power of the disconnector and turn on the power switch.
3. After the device is connected, press the power switch disconnector to work. At this time, all the mobile phones on the site are in the state of searching for the network and lose the base station signal. Neither the calling party nor the called party can establish a call connection.
basic skills:
1 Slow start function
After the shield is energized, the working power rises from zero to stable within 4 seconds.
2 Shield function
After the activation is completed, the mobile phones within the range are blocked for 35 seconds.
