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The Computer Revolution/Networks/Digital and Analog Cell Phones

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Digital Cellphones

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"Digital cell phones are the second generation (2G) of cellular technology. They use the same radio technology as analog phones, but they use it in a different way. Analog systems do not fully utilize the signal between the phone and the cellular network -- analog signals cannot be compressed and manipulated as easily as a true digital signal. This is the reason why many cable companies are switching to digital -- so they can fit more channels within a given bandwidth. It is amazing how much more efficient digital systems can be. Digital phones convert your voice into binary information (1s and 0s) and then compress it (see How Analog-Digital Recording Works for details on the conversion process). This compression allows between three and 10 digital cell-phone calls to occupy the space of a single analog call.

Many digital cellular systems rely on frequency-shift keying (FSK) to send data back and forth over AMPS. FSK uses two frequencies, one for 1s and the other for 0s, alternating rapidly between the two to send digital information between the cell tower and the phone. Clever modulation and encoding schemes are required to convert the analog information to digital, compress it and convert it back again while maintaining an acceptable level of voice quality. All of this means that digital cell phones have to contain a lot of processing power."

retrieved from http://electronics.howstuffworks.com/cell-phone5.htm on Feb 27, 2007

Digital cellphones can run on 4 different networks and they are: TDMA, FDMA, GSM, CDMA and how they work can be found from this link http://electronics.howstuffworks.com/cell-phone7.htm.

The digital phone has revolutionized from second generation (2G) to (2.5) and to what is now the third generation (3G) of digital technology. These 3G digital phones possess greater capabilities and increased speed to handle new features such as video, gaming and internet connection.

Advantages of Digital Cell Phones

  • better quality of sound and service
  • more security, eavesdropping protection
  • ability to support next generation services
  • stronger battery life
  • more resistant to noise
  • increased capacity

Analog Cellphones

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Analog was the first technology used in cell phones and uses a range of frequencies, 832; two frequencies made up a channel. 30kHz was determined to be the width of the analog voice channel because it provided the closest quality to that of a landline. Each carrier has 395 voice channels and 21 data channels. While innovative at the time they are accompanied by numerous disadvantages. The battery life and talk time is short, they are more susceptible to dropped calls and interference due to outside noise, analog is unable to provide much of the multimedia characteristics of digital phones and they require larger sources of power and therefore have a high frequency of interacting and disrupting medical devices. One of the positives of analog technology is that the coverage is superior to that of digital, in the US 95% of the country is compatible with analog. As digital cell phone technology increases, analog will become extinct due to every disadvantage of analog being solved through digital with few new draw backs.

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