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Mobile Phones |
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| New age Digital phone |
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| With the advent of digital technology mobile phones took a big leap forward. |
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| The biggest advantage of the digital technology is that any data whether it is a voice or a text or a picture can be converted into bits and bytes. Earlier the difference between various signals whether radio or TV was that of different frequencies and modulations. These signals were what we call as Analog signals. The characteristic feature of an analog signal is that it is in the shape of a Sine curve, that is; it rises and falls in the shape of a bell. Thus you could not have used the TV signal to be sent over a computer, or a radio signal over a TV etc. |
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| Digital Mobile Phone |
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| Digital mobile phone use what is known as frequency shift keying. The 1s and os are sent using two frequencies. It is the complex circuits inside the mobile phone that convert the analog information to digital and vice versa. |
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| There are three universal technologies used by Digital mobile phone networks for transmitting information. |
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Frequency division multiple access (FDMA) |
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Time division multiple access (TDMA) |
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Code division multiple access (CDMA) |
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| The first word defines the access method is. The second word, division describes how the calls are split based on the access method. |
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FDMA puts each call on a separate frequency. |
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TDMA assigns each call a certain portion of time on a designated frequency. |
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CDMA gives a unique code to each call and spreads it over the available frequencies. |
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| The last part of each name is multiple access. This simply means that more than one user can utilize each cell. |
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| We have discussed the various technologies for communication; let us now look inside the cell phone. |
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