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How a cell phone works?

Today almost everyone is using cell phones but do we know how it works?
Cell phone is basically the combination of two technologies or inventions. One is the telephone and other is the radio. Telephone was the invention of Graham Bell in 1876 and radio by Nikolai Tesla in 1880’s which made a way for the wireless communication. Cell phones are much like a radio which receives the signals from towers.

Before the invention of cell phones people who want to have the wireless communication uses a radio device in their cars with an antenna on the top of car that receives the analog signals.

The working of cell phones are based on the technique of “frequency reuse” through the “cells”. A particular city is divided into small cells and the two individuals communicate through these cells. Frequency reuse is a technique in which one cell works on the previous cell frequency. These different cells have transistors which are required for the transmission of information from one cell to another. So transistors controls the different cells of an area and these transistors are further controlled by the towers.

In the whole process the service provider companies set stations and towers that cover a particular area. This station or cell is connected to other cell and forms a network for the transmission of information. All these small cells or station is controlled by the main network where the information or call is sent to another area or service provider. For e.g.:- when we call a person the number is sent to these station and then signal goes to the nearest cell of the receiver then the cell of the receiver send back the information to the nearest cell of the caller that the particular person has received the call. This seems to be a complex process but it does not take much time.

This information goes through electromagnetic waves which are received by antennas of the tower at the base station. These signals can be sent even through obstacles like wall. It does not require the sight of station for communication.

Cell phone of 2nd generation uses the network technologies that are:-

FDMA (frequency division multiple access)
It is used for analog transmission and is not taken as capable of digital transmission. FDMA puts each call on different frequency like every station of radio send signals using different frequencies within the particular bandwidth.

TDMA (time division multiple access)
It divides the frequency in time slots. It has narrow bandwidth of 30 kilohertz and 6.7 milliseconds in length are divided according to the time in three time slots.

It works with SIM card but some companies lock the phone so that it can use only their services. It works within the frequency 900 megahertz and 1800 megahertz in Asian and European countries, 850 to 1900 megahertz in U.S.

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