The test signal jammer has a radius of about 1.3 kilometers, which may have an impact. The mobile phone signal shielding device uses the latest Israeli interference technology to generate stable electromagnetic signals, covering mobile communication GSM, CDMA, GPRS, local calls, and PHS frequency bands, so that mobile phones cannot be used in certain specific places, thereby solving some problems in life. negative effects due to cell phone signals.
Relevant test supervisors will turn on wireless wifi signal jammer in each test center, which will seriously affect the normal communication of mobile phones in the test center area and surrounding customers, which is manifested as inability to make and receive calls, inability to access the Internet, and unsuccessful information transmission and reception.
The principle of blocking mobile phone signals
The mobile phone signal jammer scans from the low frequency band of the forward channel (the channel from the base station to the mobile phone) to the high frequency band at a certain speed during the working process, causing interference in the process of receiving the message signal by the mobile phone, so that the mobile phone cannot detect the signal from the base station. The normal data sent out, so that the connection with the base station cannot be established, and there is no signal and no service state.
For example, when the mobile phone communicates with the base station, the signal jammer is like a troublemaker, deliberately making noise around you. The noise signal is so large that the mobile phone can't hear what the base station is saying, and the base station can't hear what the mobile phone says. In fact, this is not to shield the mobile phone signal, but to bury the signal sent by the mobile phone in a large number of noise signals, so as to achieve the purpose of interference.
At present, the mobile phone signal blockers used in the examination room are all frequency bands, which can interfere with all frequency bands of 2G/3G/4G/5G of the three operators, and can also block all WIFI signals and Bluetooth signals. The above is the principle of mobile phone signal jammer. However, the frequency band of electromagnetic waves ranges from several Hz to tens of hundreds of GHz, and each segment may be used as a signal for communication.
In this context, radio communication tools with dedicated frequency bands "came into being". The operating frequency band of these devices is selected outside the frequency range covered by the cell phone jammer, and the cell phone jammer does not work on them. For this special radio communication tool, the examination room is specially equipped with a monitoring vehicle equipped with a radio monitor for real-time monitoring of radio wave signals of unknown origin.
So how exactly do radio detectors work? Because electromagnetic waves have the characteristics of "closer and far smaller", by constantly moving the detection vehicle, the monitoring equipment can locate the position of the signal transmitter according to the distance and the strength of the signal, and capture the offenders who use these radio communication tools on the spot. Nowadays, drones have also appeared in the college entrance examination room, which can perform signal positioning faster.
Therefore, neither mobile phones nor these special radio equipment can play a role in the college entrance examination room.
