Due to previous fraud on communication equipment during previous college entrance exams in recent years, in order to completely eliminate the occurrence of such phenomena, the signal jammer has been used as a big move.
So, what is the principle of the barrier used in the college entrance examination? In fact, which equates to time your phone to send and receive information, cell phone jammer like a super horn super, the output of ‘noise signal’ too big for your phone can not hear, ‘mouth’ but also call jammers. To put it simply, the work of the shield is far from blocking the signal from the cell phone, but blocking the signal. Equivalent to the use of electromagnetic signals useful in a large number of undesirable signals.
Although the phone is used whenever wireless communication devices, but there is also slip the invisible line than the mobile base stations. The first step for a mobile phone to make a phone call or answer a phone call is to first establish a connection with a nearby mobile phone base station. If you are left-handed and right handed each a mobile phone, a mobile phone to call the right hand with his cell phones in the left hand, electromagnetic mobile phone waves are not transmitted directly from the left hand the right hand so simple, but will be a roundabout road passes a few hundred meters from the phone to the left hand The base station of the mobile phone, then a large circle to the right phone (except Bluetooth).
This is why the signals in the examination room were disrupted, which seriously disrupted the call of mobile phone users around the examination room and the quality of the call became very bad. For the flowers of the homeland, everyone please support for a few days.
However, is this mask really effective? The entire frequency range of the electromagnetic wave ranges from the smallest Hz to the largest one several hundred GHz, and the range is very large.Each segment can be used as a communication signal.But with the exception of a few devices very specialized, the usual protection devices are “The trick is not big enough” and “the five sounds are incomplete” A shield can block only a small part of the frequency band Communication tools can use bands unshielded frequencies to communicate.
So increasing the number of jammers is an imminent thing and trying to keep all areas covered.