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Name: Jesse
Status: Student
Age: 9-12
Location: N/A 
Country: United States
Date: April 2006


Question:
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?



Replies:
Jesse,
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.

Ryan Belscamper



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