Asymmetric Digital Subscriber Line

Asymmetric Digital Subscriber Line
From Wikipedia, the free encyclopedia
Jump to: navigation, search
Please wikify (format) this article or section as suggested in the Guide to layout and the Manual of Style.

Remove this template after wikifying. This article has been tagged since October 2006.ADSL standards
ADSL
ANSI T1.413-1998 Issue 2

G.DMT
ITU G.992.1

G.Lite
ITU G.992.2

ADSL2
ITU G.992.3/4
ITU G.992.3/4 Annex J
ITU G.992.3/4 Annex L

ADSL2+
ITU G.992.5
ITU G.992.5 Annex L
ITU G.992.5 Annex M

Asymmetric Digital Subscriber Line (ADSL) is a form of DSL, a data communications technology that enables faster data transmission over copper telephone lines than a conventional modem can provide. It does this by utilizing frequencies that are normally not used by a voice telephone call, in particular, frequencies higher than normal human hearing. This signal will not travel very far over normal telephone cables, so ADSL can only be used over short distances, typically less than 5 km. Once the signal reaches the telephone company's local office, the ADSL signal is stripped off and immediately routed onto a conventional internet network, while any voice-frequency signal is switched into the conventional phone network. This allows a single telephone connection to be used for both ADSL and voice calls at the same time.

Contents [hide]
1 Explanation
2 How ADSL works
2.1 On the wire
2.2 Modulation
3 ADSL standards
4 Installation issues
4.1 Footnotes
5 See also
6 External links



[edit] Explanation
The distinguishing characteristic of ADSL over other forms of DSL is that the volume of data flow is greater in one direction than the other, i.e. it is asymmetric. Providers usually market ADSL as a service for people to connect to the Internet in a relatively passive m