It is also a special place for some special industries. On a plane, for example, when the plane is ready to take off, the radio and on-board staff will tell passengers to fasten their seat belts and turn off their phones (or turn on airplane mode) to make sure the plane can work without interference from other signals. There are also units such as gas stations or petroleum and petrochemical plants, which also indicate that telephone calls and open flames are prohibited. So why can't gas stations make calls to cell phones? Because a large number of gasoline molecules are mixed in the air of the gas station, gasoline is easy to volatilize, so when it encounters an open flame or other substances, it will cause a spark explosion, and the mobile phone we use will release it when you fuel. Call or text. Electromagnetic waves, which collide with ions in the air, also produce sparks. Because mobile phones have the functions of transmitting information, video, recording and other functions, it is easy to cause the leakage of important information of the state and related institutions. Many countries have relevant methods and laws to restrict the use of mobile phones by some important departments or important persons. Wireless communications equipment to protect national interests. For example, some places that require high confidentiality of information, such as government office buildings, military combat command agencies, financial centers such as banks or securities, and examination rooms. The most contact is the examination room. Basically every school will install Cell Phone Blcoker Alarm System to prevent candidates from cheating. At the end of the term, simulation, college entrance examination or some qualification examinations, as long as the mobile phone enters the shielding range, it cannot be received. Signal or signal is weak.
Cell phone jammers, also known as wall mounted smartphone signal detectors and cell phone radio frequency jammers, can generate specific electromagnetic signals that cover both GSM frequency bands. The three main frequency bands of a frequency band of CDMA limit the use of mobile phones in some specific areas that need to be shielded, such as within ten meters to forty meters, while other areas that do not need to be shielded will not be artificial. However, is this Cell Phone Blcoker Alarm System really that effective? The entire frequency range of electromagnetic waves ranges from a minimum of a few hertz to a maximum of several hundreds of GHz, and each segment can be used as a communication signal, but except for a few very professional devices, ordinary signal jammers "sound" is not loud enough" and " Five tones are incomplete". Signal jammers can only shield a small part of the frequency band, and communication tools can use the unshielded frequency band to communicate. Of course, the 2G, 3G, and 4G mobile phone services of several domestic communication companies are all concentrated in a few small frequency bands. cell phone jammer in the examination room can still be concentrated on these frequency bands.
