Introduction to ADSL

Asymmetric Digital Subscriber Line is a form of DSL. ADSL is a data communications technology (modem technology) that enables faster data transmission over copper telephone lines than any conventional modem can provide.

ADSL is transforming the existing public network from a network that was limited to voice, text and low resolution graphics to a powerful network capable of bringing multimedia, including full motion video, to everyone's home. Another important advantage of ADSL is that it allows the plain old telephone system (POTS) signal to co-exist with the ADSL data signal. The service is 'always on' and is usually charged at a flat rate regardless of time on-line or data used.

ADSL characteristics:

1. Asymmetric – The data can flow faster in one direction than the other. More precisely, Data transmission is faster downstream (to the user) to the subscriber than upstream (from the user). Costumers do not need a high bi-directional transmission speed. They actually connect to the internet in a relatively passive mode because the amount of data they download is enormously higher than the amount of data they transmitting.
2. Digital – No type of communication is transferred in an analog method. All data is purely digital, and only at the end, modulated to be carried over the line.
3. Subscriber Line – The data is carried over a single twisted pair copper loop to the subscriber premises
   

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