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froten
Joined: 17 Jun 2006
Posts: 20
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 05 Jul 2006 10:38 Data transmision on the telephone line |
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| I would like to know how data (didgital data specialy) are sent on the tephone lines? is it sent as analog or digital or some sort of modulation?
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m_llaa
Joined: 12 Mar 2006
Posts: 272
Helped: 23
Location: My Love Iran
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| 06 Jul 2006 17:43 Re: Data transmision on the telephone line |
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Salam
It depend on u. It is looklike another transmision line. u can send data with analog or digital modulation, but digital is common today. for example broadband internet connection like ADSL use telephone line and use digital modulation i think QAM.
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zolam
Joined: 03 Oct 2005
Posts: 102
Helped: 9
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| 08 Jul 2006 20:52 Re: Data transmision on the telephone line |
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it depends what do you understand by digital data transmission
usually phone lines are long ones and the copper tiles are interrupted by some kind of trafos so you cannot look at them like to "bus" logical data
usually we send defined frequencies for, discret or in packets - each frequency representing some coded information.
from the early days of 103 standard or telegraph when we sent two frequencies, one for 0 and one for logic 1 (usually about 2020 and 2220 Hz), nowdays we use different coding methods and packets, and in VDSL transmissions you can get over 8MBPS (megabit per second) using modulation techniques of course
if you want more info, just let me know and i ll be more specific
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