[PART - 2] Electromagnetic Pollution [RU]

A mobile phone allows calls into the public switched telephone system over a radio link. Early mobile phones were usually bulky and permanently installed in vehicles; they provided limited service because only a few frequencies were available for a geographic area. Modern cellular "cell" phones or hand phones make use of the cellular network concept, where frequencies are re-used repeatedly within a city area, allowing many more users to share access to the radio bandwidth. A mobile phone allows calls to be placed over a wide geographic area; generally the user is a subscriber to the phone service and does not own the base station. By contrast, a cordless telephone is used only within the range of a single, private base station. A mobile phone can make and receive telephone calls to and from the public telephone network which includes other mobiles and fixed-line phones across the world. It does this by connecting to a cellular network provided by a mobile network operator. In addition to telephony, modern mobile phones also support a wide variety of other services such as text messaging, MMS, email, Internet access, short-range wireless communications (infrared, Bluetooth), business applications, gaming and photography. Mobile phones that offer these more general computing capabilities are referred to as smartphones. The first hand-held mobile phone was demonstrated by Dr Martin Cooper of Motorola in 1973, using a handset weighing 2 1/2 lbs (about 1 kg).[1] In 1983, the ...

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