History of Mobile phones
IN THE EARLY 19908, THE MOBILE PHONE (or cellphone) was a rare luxury, but in recent years it has outsold almost every other electrical gadget -as a professional tool, domestic convenience, and even a fashion accessory. Mobile phones have also generally shrunk in size, due to improvements in rechargeable batteries, which now store more electricity for longer in a smaller package, and to smaller, more efficient electronics that use less electricity. A “mobile” is basically a low-power radio receiver-transmitter, plus a tiny microphone to convert sounds into electrical signals, and a small speaker that does the reverse. When the mobile phone is activated, it sends out a radio signal that is answered by nearby mast transmitter receivers. The phone locks onto the clearest signal and uses this while within range (the range of each transmitter is known as a cell). The phone continuously monitors signal strength and switches to an alternative transmitter when necessary. The phone’s liquid crystal display (LCD) shows numbers, letters, symbols, and colour pictures. Newer models have a larger screen for more complex colour images, and commonly incorporate a camera, radio, and MP3 functionality. Smartphones, which are increasingly widespread, contain additional software and more may be downloaded. Smartphones typically offer Internet and email access, PDA-like functions , and may even contain GPS navigation software.
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