With the approach of the college entrance examination, many test centers have begun to install full-band cell phone signal jammer in the test room in order to prevent candidates from cheating through mobile phones and other communication devices. As a good helper that can effectively eliminate and prevent cheating. Schools and teachers are not unfamiliar with it, but if there is a base station in the school and it is not very far from the examination room, will the effect of the full-band jammer be affected?
First of all, we need to understand the working principle of the full-band jammer. When the mobile phone is working, within a certain frequency range, the mobile phone and the base station are connected by radio waves to complete the transmission of data and sound with a certain baud rate and modulation method. Most of the full-band jammers are made by sending
Radio interference signal to achieve mobile phone signal shielding. By transmitting a high-power signal of a certain frequency, the surrounding electromagnetic environment is severely damaged, and the mobile phone cannot obtain and analyze the signal from the base station normally, so as to achieve the purpose of shielding the mobile phone signal.
If there is a communication base station in the school, the strength of the transmitted signal is stronger and more stable, and it is less likely to be shielded by the signal jammer. The shielding effect of the full-band jammer will naturally be greatly reduced. The impact is very large, so what should we do to achieve a stable and reliable shielding effect?
(1) Because the examination room needs an absolutely quiet environment, the high-power machine has a large transmission power, and a better heat dissipation environment is required, and the noise is relatively large. Therefore, it is not realistic to replace the high-power full-band jammer. You can add machines on the basis of the original low-power full-band shielding device to meet the shielding requirements.
(2) Most of the full-band shielding devices used in the examination room use omnidirectional antennas. The shielding distance can be improved by changing the directional antenna, which has met the shielding requirements of the entire examination room.
(3) Contact the base station operator through the school, and adjust the direction of the directional antenna of the base station. The front of the antenna should not face the examination room. The signal strength of the base station has been reduced. Or temporarily shut down the operator's base station when taking the test.
How big is the range of the mobile phone signal jammer? This may be a question that many people will consider when purchasing a mobile phone signal jammer. But the answer is not certain, we need to look at the specific situation and analyze it in detail.
The principle of the signal jammer is like this, the jammer scans from the low-end frequency of the forward channel to the high-end at a certain speed during operation. The scanning speed can form garbled code interference in the message signal received by the mobile communication, and the mobile communication cannot detect the normal data sent from the base station, so that the mobile communication cannot establish a connection with the base station. Mobile communication is manifested as searching the network, no signal, no service system and other phenomena.
For example, the radio we usually listen to is FM88.3, which tells the frequency of your city. Then, I can also get one with the same frequency, but my frequency is illegal if it is not reported to the local Radio Regulatory Commission. To interfere with your normal radio frequency.
The shielding radius of high-power signal jammers used in prisons can reach hundreds of meters, while the shielding radius of low-power jammers suitable for examination rooms and conference rooms is generally between 1-10 meters, depending on the strength of nearby signal base stations. .