Install a mobile cell phone signal detector in the examination room to prevent cheating
It's the time of the annual college entrance examination again. Why are there such situations around the exam site during the college entrance examination that "cannot make and receive calls, cannot access the Internet, and send and receive unsuccessful information"? This starts with the cell phone signal detector for the college entrance examination.
Since there were precedents of using communication equipment to cheat in the college entrance examination in the past few years, in order to completely eliminate the occurrence of such phenomena, the test center used the big trick of cell phone signal detector.
So, what is the principle of the mobile cell phone jammer currently used in the college entrance examination? In fact, it is equivalent to when your mobile phone is sending and receiving information, the mobile phone jammer acts as a super loud speaker, releasing "noise signals" so big that your mobile phone "inaudible", "mouth" can't be more than mobile phone interference The "sound" of the device is bigger. Simply put, the working principle of a cell phone signal detector is not to block the mobile phone signal, but to block the mobile phone signal. It is equivalent to obliterating useful electromagnetic wave signals in a large number of useless signals, so as to achieve the purpose of interfering and blocking mobile phone signals.
Although a mobile phone is a wireless communication device that is used wherever it goes, there are actually invisible wires dragging it, that is, the communication base station built by the operator. Whether our mobile phone is making a call or answering a call, the first step is to establish contact with a nearby communication base station. If you hold a mobile phone in each of your left and right hands, use the mobile phone in your left hand to dial the mobile phone in your right hand, the electromagnetic wave of the mobile phone is not as simple as transmitting directly from the left hand to the right hand, but will travel from the left hand mobile phone to several hundred meters away. Communication base station, and then take a big circle and send it back to the right-hand mobile phone (except for Bluetooth function).
This is why not only the examinees in the examination room are blocked by cell phone signal detector, but also the wireless signals around the examination room are also interfered, which seriously affects the normal communication of users in the surrounding areas of the examination room, resulting in the inability to make and receive calls. Internet access, unsuccessful sending and receiving of information, etc. So, once again warmly reminded, for the flowers of the motherland, please bear with me for two days.