Since the invention of the telephone, the phone tools enable mankind to fully enjoy the convenience of a modern information society, but this is only a beginning after the acquisition of housing, and universal scope is not wide, as the wireless telegraph and the invention of radio, people We hope to have a way to carry, without phone line. Shoulder Scientists hope of mankind, mobile phones have made unremitting efforts. Due to the need of the two world wars, the early prototype of mobile phones has been developed out as walkie-talkie, walkie-talkie. Among them, the walkie-talkie in 1941, the US Army began the equipment, then the use of the band is shortwave band, the device is tube. From the beginning of the 1950s, and later developed using 150 92 400 qe, there followed 60 years of the transistor, private wireless phone systems have emerged, used in public security, fire, taxi and other industries. However, these can be used only in a few special populations and carry inconvenient, so people look forward to smaller, more convenient for the public to use personal mobile phone appears. With deep electromagnetic research, the advent of large scale integrated circuits, placed in front of one scientist's hurdles have been cleared, the mobile phone is first produced. It mainly consists of the handset, the control means, the antenna and the power supply 4 parts. On the handset, in addition equipped with a microphone and headphones, as well as numbers, letters, display, control keys and dial keys and so on. Control unit has a number of important functions modulation, demodulation. Since handheld mobile phone use is on the move, thanks to self-contained battery power required to supply, then the use of nickel-cadmium batteries Samsung A7 case after the acquisition can be recharged. Mobile phone manufacturers out how to plan a network is a problem. Scientists first thought honeycomb structure, architecture, on the honeycomb structure is a cost-effective manner, the mobile network can be taken in the same way, then use different frequencies in adjacent cells, the cells in the far distance on the same frequency. This will not only effectively avoid frequency conflicts, but also make the same frequency used multiple times, saving frequency resources. This theory neatly solves the conflict and cross-channel service coverage area automatic conversion problems limited radio frequency and number of high-density user demand first-generation mobile phone system, a typical representative of the United States six 1 ^ 1? 3 system and later Ding eight Improved system 08, as well as small and XV \ Tintin and the like. Advanced Mobile Phone System) use analog cellular transmission 'lose 800 bands, are widely used in the Americas and parts of the Pacific Rim countries; DING eight people omnidirectional Mobile System) is a 1980s European standard analog mobile phones, but also China 80 analog mobile phone standard to acquire a large number of mobile phone shell after years of use, the use of 900 bands. Nordic Sweden also opened a small XV ('out mobile phone) system, the German opening 0-450 system. The first-generation mobile phone system is analogue, with eight technology. Second-generation mobile phone system based on the transmission of voice and data-based digital mobile phone system, a typical system has 031 ^ 1 (using small 0X4 eight eight eight ways ... ??, 13-95001 ^ VIII and Japan is now renamed ? 00 other digital mobile phone system .20 In addition to providing voice phone service outside can also provide low-speed data services and short message service. Global System for Mobile> series are 031 ^ 1900,0031800 and? 031,900 three parts, between the three The main difference is the difference between operating band of its characteristics can be summarized as follows: ^ high spectral efficiency: As a result of efficient modulators, channel coding, interleaving, equalization, and speech coding technology, the system has a high spectrum efficiency professional original phone after shell Acquisition | shell after the acquisition of Hunan | Obo Obo electronic is supplied by Shenzhen Electronic Technology Co., Ltd. Shenzhen City Aobo Electronic Technology Co. (www.aobodz.com) strong, credible, in other industries in Shenzhen, Guangdong has accumulated a large number of faithful. The client company better work attitude and continuously improve innovative ideas will lead Obo electronics into the brilliant and you work for a better future!