Home     
 
 


   Top Subjects

Batteries
CDs
Cell Phones
Digital Cameras
Home Networking

Sponsored By:

   Categories
  
Building Blocks
Computers
Gadgets
Home Theater
ShortStuff
Telecommunications
Browse the Electronics Library

    
Main > Electronics > Telecommunications

How Cell Phones Work
by Marshall Brain and Jeff Tyson


 Introduction to How Cell Phones Work
The Cell Approach
From Cell to Cell
Cell Phones and CBs
Inside a Cell Phone
AMPS
› Along Comes Digital
Cellular Access Technologies
Cellular vs. PCS
Dual Band vs. Dual Mode
Problems with Cell Phones
Cell-phone Towers
Lots More Information

Along Comes Digital
Digital cell phones 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!

Lowest Price
1.Sprint Samsung SPH-i500 Mobile Phone $549.99
2.Handspring TREO 600 GSM/GPRS COMMUNICATOR CELLPHONE PALM ORGANIZER WIRELESS $499.00
3.Handspring Treo 270 Communicator - Phone & PDA - No Service $99.00
4.Sony Ericsson P900 (unlocked) $500.00
5.TREO 600 PDA/PHONE SPRINT PCS NETWORK ONLY WIRELESS CDMA $599.95

 

 
<< Prev Page    Intro    Next Page >>

  HSW Home


Table of Contents:
Introduction to How Cell Phones Work
The Cell Approach
From Cell to Cell
Cell Phones and CBs
Inside a Cell Phone
AMPS
› Along Comes Digital
Cellular Access Technologies
Cellular vs. PCS
Dual Band vs. Dual Mode
Problems with Cell Phones
Cell-phone Towers
Lots More Information


 
Search Google:
powered by Google  
Rate this Article!
 


Copyright � 1998-2003 Howstuffworks, Inc. All rights reserved.

Lycos (R) s a registered trademark of Carnegie Mellon University.

Privacy Policy | Children's Privacy Notice | Terms and
Conditions |  Standard Advertising Terms and Conditions