Microwaves and Information Transfer
Country: United States
Date: April 2006
How do microwaves carry messages from one mobile
phone to another? How is the message kept intact, and why can the
persons voice still be recognised at the other end?
The transmission from any one cell phone is not a continuous, clear signal.
Instead, the signal has been modified by the phone to shift
frequencies slightly, or even pulse on and off rapidly. (modern
cell phones tend to use the latter, but I will explain both)
This process of putting the informaiton on a signal is called "Modulation".
In the first case, where the frequency is being shifted, that change
is equal to the tones in your voice. Once recieved by another cell
phone, that phone removes the original carrier wave, (the particular
microwave frequency that is carrying the information), and all that
is left is the tones that were spoken into the first phone.
In the second case, the voice of the person speaking is first
reduced to a digital signal, (a seiries of ones and zeros), much
like Things you find on the internet, or the music on a CD. This
string of ones and zeros is then used to turn the carrier tone on
and off. The recieving phone then reverses this process, and uses
those ones and zeros to re-create the original sounds.
I have simplified this explination just a little bit, as cell phones
actually do not talk directly to eachother. Instead, they talk to
the nearest cellphone tower, which connects tot he regular phone network.
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Update: June 2012