Signal jammer can really block all signals?

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Although this year’s college entrance exams have been postponed to July 7-8 due to the epidemic, the corresponding measures to ensure information security in the exam rooms have not been reduced in any way. Carriers have issued an announcement that they will turn on wireless signal blockers during the exam period in accordance with the Education Bureau’s requirements, which will affect the quality of communication for cell phone users around the school. It will not return to normal until the exam is completed. What is the impact of turning on the signal blocker during the college entrance exams? The invigilator at the entrance of the examination hall is wielding a metal detector. Does it really work?

To know what is the effect of shielding cell phone signals, we first understand the task principle of mobile communication. Cell phone as a mobile communication device, in communication needs to establish a connection with the base station near the left, and then access the core network to find the communication destination. In the above process, all information is carried and transmitted through electromagnetic waves. The electromagnetic wave band used by cell phones is related to the fragmentation of cell phones and operators. But in general, the three operators use the electromagnetic wave band scattered in the 850-4900MHz range. If the organizers of the college entrance examination want to shield the cell phone signal in the examination room, can not let the examination room near the 2G/3G/4G/5G base station does not work, otherwise all the communication devices in the area can not communicate normally. Then the only way is to shield the cell phone signal in the examination room.

When it comes to shielding cell phone signals, the first thing that comes to mind is metal shielding, which means that the phone is placed in a blocked metal box, blocking electromagnetic waves through the metal transmission. However, it is obviously impractical to turn all the classrooms in the examination room into metal blocked classrooms. So what do we do? It’s complicated. All you need is a small cell phone signal blocker to block all cell phone signals in the exam room.

Cell phone 5g jammer work process from the forward channel (base station to the cell phone channel) of the low frequency band at a certain speed scan to the high frequency band, when the cell phone to accept the SMS signal constitutes a disturbance, so that the phone can not detect the data sent from the base station normal, can not establish a connection with the base station, showing no signal, no service form. For example, when the phone communicates with the base station, the signal jammer is like a messenger, deliberately creating music around you. The noise signal is so loud that the phone can’t hear what the base station is saying, and the phone can’t hear what the base station is saying. In fact, this is not to shield the cell phone signal.

The current examination room use of cell phone signal shields are full-band, can stir the three major operators 2G/3G/4G/5G all bands, WIFI signal and Bluetooth signal can also be shielded. The above is the principle of cell phone signal shield. However, the frequency range of electromagnetic waves from a few Hz to several hundred GHz, each segment can be used as a communication signal. Will there be some special frequency bands used in the examination room? The same is true about other radio communication tools, radio communication tools with a common frequency band in this context “emerged”. These devices have been chosen to operate in the frequency range outside of that covered by cell phone jammers.

About this special radio communication tools, the examination room is specially equipped with a radio monitor monitoring vehicle, used to monitor the radio waves from unknown signals in real time. So how is the task of the radio detector? Because electromagnetic waves have a “near large and far” characteristics, after moving the detector car from time to time, monitoring equipment can be based on the interval and signal strength to locate the signal transmitter, and the application of these radio communication tools to capture criminals on the spot. Nowadays, drones are also presented in the college entrance examinations, which can stop signal positioning faster. Thus, neither cell phones, nor these special radio devices can play a role in the college entrance exams.