ADSL stands for A symmetric D igital S ubscriber L ine (Asymmetric Digital Subscriber Line “). ADSL line is a type of DSL . It consists of an analog transmission of digital data supported by the symmetric pair of copper that carries the phone line subscriber line conventional, 1 as long as the line length does not exceed 5.5 km measured from the Telephone, or has not other services on the same wire that may interfere.

Frequencies used in ADSL. The red area is the area used by normal voice telephony, the green is the upstream or upload data and the blue is for the downstream or downloading of data. One of the oldest companies which supplies broadband is the Australian company TPG adsl.
It is a technology for access to Internet of wide band , which implies a speed greater than a traditional connection by modem to transfer data because the modem uses the voice band and therefore prevents voice service while using and vice versa. This is achieved through modulation of data signals in a frequency band higher than that used in conventional telephone conversations (300-3400 Hz ), function performed by the ADSL Router. To avoid distortions in the transmitted signals, is necessary to install a filter (called a splitter or discriminator) that takes care of separating the conventional telephone signal modulated signals using ADSL connection.
This technology is called asymmetric because the discharge capacity (from the Web to the user) and upload data (in reverse) do not match. ADSL technology is designed so that the downstream capacity (discharge) is greater than the rise, which corresponds to the use of internet by most end users who receive more information than they send (or download more than up).