The test uses the mobile phone signal jammer in the test room to prevent the signal from "chaotic entry"
In school, exams are naturally indispensable; exams in the information age are naturally indispensable to the addition of mobile phone signal jammers in the examination room. With this device, at least it is almost impossible to cheat by using a mobile phone. So what kind of device is it?
As far as we know, the cell phone blocker in the examination room is mainly aimed at various examination rooms and places where the use of mobile phones is prohibited in schools. In such an occasion, the signal will no longer be transmitted with it.
The mobile phone signal jammers currently on the market can limit mobile phone signals that are 200 meters away from the launch pad and have a radius of >20 meters. The shielding radius is adjustable, it only shields the signal of the mobile phone, and does not affect other electronic devices. Save power, the power is 20W.
When the mobile phone works, it is within a certain frequency range. The mobile phone and the base station are connected through radio waves, and the data and sound transmission is completed with a certain baud rate and modulation method. According to this communication principle, the mobile phone signal jammer in the examination room scans from the low-end frequency of the forward channel to the high-end at a certain speed during the working process. This scanning speed can form garbled code interference in the message signal received by the mobile phone, and 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. The mobile phone shows phenomena such as searching the network, no signal, and no service system.
There are many common mobile phone signal jammers on the market, such as the mobile phone signal jammer-818B series independently developed by our company, which adopts advanced shielding technology. Can control a range of about 40 meters in diameter, use DC-DC converter input voltage, 5V output voltage; each frequency band channel works independently, effectively shielding: DCS, CDMA, WCDMA, GSM, FDD, TD-SCDMA, TD-LTE, WIFI /Bluetooth and other mobile phone signals;
(1) The 818B stand-alone version can be used continuously for a long time after being connected to the power supply;
(2) The 818B2 network intelligent version can realize functions such as remote power on and off, timing, free grouping and sub-area control and management through network, power carrier, wireless communication and other communication methods;
Shielding is only carried out for the frequency band defined by the equipment, without affecting and interfering with the normal operation of other electronic equipment; under normal circumstances, ideal shielding effects will be obtained only when used at a place 300 meters away from the base station;
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