2012年6月28日星期四

The school has to ensure cell phone jammer they provide

The real running state of  cell phone jammer  can provide much information
GSM900/1800 dual-band between the switching time is short, the success rate, the signaling load. Dual-band handsets a high proportion of the balance of the business of the GSM900 and GSM1800 double-layer gateway is easy to implement. The limitations of this networking, basically do not use the existing network. GSM1800, on the other hand, the operating frequency is higher than GSM900, radio propagation attenuation is greater than the GSM900, which brought new difficulties to the operation and optimization of dual-band network. Digital cellular system in the 1800MHz band typical path loss than the 900MHz band more than 8dB, the same 50 m long antenna feeder loss of about 1.5dB more than 900MHz, so under the same conditions, GSM1800 coverage will be less than GSM900. The school has to ensure cell phone jammer they provide.
Based on conventional GSM1800 experimental reports in the urban environment: to ensure good call quality within a radius of one kilometer, 1 km (attenuation greater than 30dB) showed a higher rate of dropped calls. The European Telecommunications Standards Institute ETSI recommendations related to the performance of the GSM900 and GSM1800 table. Different frequency bands of the radio wave propagation path is different, for the 900MHz band wireless communication systems, radio propagation mode is the space wave, namely, the direct wave, reflected wave synthesis wave. The phone constantly to be around (within a few meters to tens of meters) of different geometry and size of buildings, trees and other obstacles or terrain undulating, its reception field strength changes are quite complex.  cell phone jammer can meet the needs and requirements caused by the specific features of the school.
Combination of multi-path, the shadow on this propagation path due to scattering, reflection, diffraction, or the straight path because of obstacles to reach the mobile phone signal amplitude, phase and angle of incidence are random, thus the phone is sometimes only move a few meters, the receiver field may be large fluctuations in the rate of change of these fluctuations and Mobile speed, waves long. 1800MHz wavelength of the waves was half of 900MHz, and thus suffered multipath fading and shadow effects will become more apparent. In theory, GSM180O the high-frequency signals should be improved ability to penetrate buildings more than GSM900. However, in 1998, China's GSM1800 network test, the experimental results reflect the slightly higher than the GSM900 GSM1800 indoor loss. For example, during the class, the use of the cell phone is not allow to ensure the normal implementation of the class so that cell phone jammer is needed to stop use of the cell phone.

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