Asymmetric Digital Subscriber Line
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ADSL (Asymmetric Digital Subscriber Line) is one of the leading methods of providing high-speed Internet service to subscribers. ADSL is a variant of DSL, with the A standing for Asymmetric, not Asynchronous as many people incorrectly believe it to be. The service is said to be asymmetric because the available upstream bandwidth is much less than the downstream bandwidth. Though there are some limitations imposed on the technology such as maximum bandwidth, and maximum distance from the Central Office, ADSL continues to be a competitive force in the Internet service market.
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History
Historically internet was served to people's homes through the use of voice frequency data modems connect to the existing copper telephone line network. This network consists of twister pair copper wires which run back to the telephone company's central office. The voice frequency data modem made use of the same frequencies as human speech, up to about 3.4kHz, and as such was only able to achieve speeds of up to 56Kbps. This also had the disadvantage of tying up the phone line whenever the modem was in use. ADSL makes use of other frequencies which are not needed by traditional telephony services, allowing an ADSL signal to exist on a copper line in addition to a voice signal.
Functionality
The Future of ADSL
See Also
References
--Durandal 10:47, 9 April 2008 (EDT)
