Mobile phones bring unlimited communication convenience and high office efficiency. At the end of November 2004, the number of mobile communication users in China reached 324 million, surpassing the fixed number of users (316 million) for the first time. A must-have item that many people have in their lives.
However, as people's awareness of environmental protection has increased, the electromagnetic radiation of mobile phone base stations has become a growing concern. Some residents do not know much about the working principle and radiation situation of mobile phone base stations, and even ignore the relevant laws and regulations of the national protection communication facilities, deliberately destroy the power supply and transmission equipment of the base station, forcibly obstruct the communication department for repairs, seriously affecting the mobile communication department. The mobile communication base station is normally erected and installed. The Supreme People's Court issued the "Judicial Interpretation of Unauthorized Destruction of Public Communication Facilities" on August 26, 2004 for similar issues.
The country has established strict technical standards1.1 Relevant technical standards promulgated by the state
In order to prevent electromagnetic radiation pollution, protect public health, and promote the scientific application and development of electromagnetic technology, the State Environmental Protection Administration and the Ministry of Health have issued the "Public Exposure Derived Limits" (GB8702-88) and the "Environmental Electromagnetic Wave Allowable Radiation Intensity Grading Standards". (GB9175-88) Two major technical standards, and promulgated the "Electromagnetic Radiation Protection Regulations" and "Environmental Electromagnetic Hygienic Standards" two technical standards. In March 1997, the National Environmental Protection Act No. 18 and the “Administrative Measures on Environmental Protection of Electromagnetic Radiation†were issued. The above standards are more stringent than the standards set by the industrialized countries in Europe and the United States. According to the above standards, the current frequency of the 900MHz frequency bandwidth used by mobile communications is less than 40 volts per meter or the power density is less than 40 microwatts per square centimeter. .
1.2 Mobile base station radiation values ​​meet the standard
In the face of all kinds of speculations and doubts caused by the electromagnetic radiation of mobile communication base stations, the Liaoning Provincial Environmental Protection Bureau conducted a comprehensive scientific monitoring and evaluation of the electromagnetic radiation of the base stations built by Liaoning Mobile Communications Corporation Dalian Branch in accordance with the standards set by the state: During the uncompleted period of the base station, the bottoming test is carried out to predict the radiation value, and the pollution prevention countermeasures and suggestions are put forward. Then, after the base station is opened, the current situation monitoring is carried out, and the problematic base station immediately stops the station rectification; finally, the base station is checked and accepted. Issue electromagnetic radiation certificate. After testing, the pass rate of the base station for online operation exceeded 98.5%, and the individual points passed the acceptance after the rectification. All of them obtained the electromagnetic radiation environmental evaluation certificate issued by the Liaoning Provincial Environmental Protection Bureau. At the same time, the provincial and municipal radiation environmental monitoring and management stations and the competent offices of mobile communication engineering construction have carried out scientific monitoring of the base stations according to the standards issued by the state. The test conclusions have the following three common points: First, the comprehensive electric field strength of any base station test points. In the 900MHz frequency band of mobile communication, the public exposure derivation limit is lower than 12V/m; the second is that the base station meets the requirements of the first-level strength safety standard of electromagnetic radiation allowable radiation field in GB9175-88; the third is the “hot spot area†that the masses reflect more strongly. The field strength test values ​​are in line with engineering technical requirements and electromagnetic radiation design safety values.
Relationship between base station density and radiation intensityThe mobile phone holder can connect to the phone at any time during the "mobile" process, and maintain a clear and stable call effect, because the mobile phone communicates with the base station and the base station controller via the wireless channel, and transmits communication information and control signals. Test signal. In order to ensure the quality of the call, the mobile phone and the base station automatically follow the agreed computer control program to dynamically adjust the call channel, electromagnetic radiation power and receiving sensitivity, and also realize intelligent registration of international and domestic roaming, switching between local and base stations, and recording call duration. Various functions such as fees. According to the above control principle, the farther the mobile phone in the BTS base station covering the radius of 500 meters to 700 meters is from the base station, the stronger the peak power of the corresponding channel and the mobile phone is. The test shows that when the GSM mobile phone talks in the building about 700 meters away from the base station, the transmitting power of the corresponding channel of the base station is about 13W, and the peak of the transmitting of the GSM mobile phone is about 2W; when the mobile phone moves to a distance of 1 to 200 meters from the base station When the base station and the GSM mobile phone corresponding channel transmission power will be automatically adjusted to about 0.1W.
It can be inferred that the higher the density of the mobile communication base station, the lower the electromagnetic radiation intensity of each base station; the closer the GSM mobile phone is to the mobile communication base station, the lower the electromagnetic radiation amount to the caller during the use of the GSM mobile phone.
Environmental protection of mobile communication base stationsThe mobile communication tower is covered with BP antennas, microwave antennas, mobile communication antennas, UHF antennas, etc., and the corresponding equipment room is filled with various modern communication equipment. However, from the statistical distribution of occupational diseases in the country, there are no signs of relatively concentrated communication technicians. Moreover, the height of the antenna of the GSM base station is generally between 35 meters and 55 meters, and the electromagnetic wave propagates rapidly in the air. Tests have shown that a power base with a transmit power of 20 watts has a power density of 0.6 μW/cm 2 in front of the antenna, which is much lower than the national standard of 40 μW/cm 2 . In addition, the electromagnetic wave is attenuated by about 6 dB when passing through a general brick wall, and the wall passing through the reinforcing bar is attenuated by about 20 dB. Therefore, when the GSM base station antenna is built on the roof of a general residential building, the residents in the house should be safe. In addition, the Chinese government is very responsible for environmental protection of electromagnetic radiation, and the mobile communication operation department also strictly controls various technical parameters in accordance with national standards.
There has always been such a misunderstanding among the majority of residents. The more the number of base stations, the greater the radiation intensity, so a contradiction is formed: on the one hand, mobile phone holders want more mobile communication base stations, and the electromagnetic coverage is as tight as possible. The more the number of channels, the better, to ensure the quality of their own calls; on the other hand, people are too sensitive to the electromagnetic radiation of the base station, worry about affecting health, and prevent the communication department from conducting communication construction. In fact, this kind of worry is not scientifically based. At present, the mobile communication network system has changed from the small-capacity large-area system in the past to the current large-capacity cell system. The transmission power required by the large-area base station is large, and the cell system has a small transmission power due to the large number of base stations. That is, the density of the base station of the cell system is higher and the radiation intensity is lower. According to experts' calculations, the electromagnetic wave of the base station of the Gaochun building is emitted horizontally, and the intensity in the vertical direction is almost zero.
summaryThe electromagnetic waves emitted by mobile communication devices are within safe limits, and the public does not have to worry about this. As long as you understand and understand electromagnetic radiation with a realistic and scientific attitude, you will find that it is not terrible. At the same time, it is believed that mobile communication companies will make a solemn commitment to public health and assume their due social responsibilities.
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