How to break the cell phone signal sign of the exam room? What is the basis for shielding the signal?
In the past, shielding devices were used in the test room. The method of shielding the mobile phone signal is to send a base station-like signal, covering the base station signal in a short distance; The mobile phone cannot find the base station signal.
However, due to the relatively high signal strength of the shield, it affects the human brain. Later it was no longer allowed.
Even if there is no mobile phone signal shielding function, other more secure and environmentally friendly detection methods can be used. Therefore, it is better not to fight this idea.
Crack the cellphone signal sign first, so that the cellphone signal understand its principle first:
Cell phone blocker are divided into omnidirectional and directional types according to the shape of the shield. The omnidirectional type is an olive shape, and the directional type is a fan shape, so the omnidirectional nameplate is better than the directional type. The shielding area is large;
Cell phone signal shielding is designed to generate certain electromagnetic waves and interfere with the downlink of your cell phone signal. If the shielding power is greater than the local cell signal power, the cell phone will not have a signal. If the shielding power is less than the local cellular signal power, a signal is issued.
The way to crack the shielding is to install a cell phone signal booster.
one. It has a specific scope
Even though the cell phone signal blocker name is called blocker, it doesn't block the signal but looks like a signal jammer. In general, the connection between the mobile phone and the mobile phone is passed through the base station, that is, the path of mobile phone, base station and mobile phone, and the signal shielding interferes with the communication path between the mobile phone and the base station, resulting in abnormal transmission. However, the base station is a common mobile phone within a certain range, so there are often situations where the mobile phone signal is not used normally in the test room.
Second, it is not a panacea
Cell phone signal blockers on the market now can limit the cell phone signal from the launch station 500m away and radius>. 20 metres. The shielding radius is adjustable. It only shields the mobile phone signal without affecting other electronic devices.
If your cell phone signal isn't good near the testing room lately, don't blame the signal blocker, it could be your own cell phone problem.
Third, the interference frequency band has regulations
The entire frequency band of electromagnetic waves is very wide, from the smallest a few Hz to the largest tens of hundreds GHz, and any segment can be used. In general, the following are commonly used:
The reception frequency band of GSM is 885 to 960 MHz;
The receiving frequency band of CDMA is 869-894MHz;
The receiving frequency band of DCS is 1805-1880 MHz.
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