|MadSci Network: Computer Science|
Hi Abe: Most of the phones do use some kind of coding method to positively identify themselves. In the case of wireless telephones (usually digital communication), the base and the handset must know each others codes. If the handset and base station recognize the code, they respond, otherwise they ignore it. That is how they distinguish a 900MHz signal from the handset and not get it confused with a noise signal from a 900MHz computer. Also, the signal strength from the phone handset is much much much stronger than the signal strength from the processor. But the interference is still there and it appears as noise. The best example is if you are in a crowded room and there is a lot of noise from foreign speaking people. You don't know what they are saying, so you ignore them just as the phone will ignore the 900MHz PC. Then someone yells your name and says something to you in English. Normally you would have ignored everything, but as soon as you heard your name (your code), you knew to listen to what was being said, and that it was meant for you. The coding methods they use is an art in itself. If you want to take a peak into this world, go to the library, and pick up any book on 'electronic communication' and just browse through it. I hope this helps. Abtin Spantman
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