ADSL is one of the most common digital Internet connection (DSL) technologies today based on telephone communications. The abbreviation ADSL stands for Asymmetric Digital Subscriber Line - asymmetric digital subscriber line.
Just yesterday…
It would seem that quite recently, while still few in number, the first owners of personal computers were content with the speed of the Internet connection via a telephone line at 16 or even 8 kbps. The maximum speed of the dial-up connection, through which access to the global network was carried out, did not exceed 56 kbps. Suffice it to recall that this speed made it possible to receive mostly Web-pages and view them, patiently waiting for the next one to open on the monitor. It took two to three days to download a movie in AVI format. DVD movies took even longer.
DSL technologies
But then DSL technologies appeared. These are technologies for high-speed digital Internet access via telephone lines. They appeared in the mid-90s as an alternative - also digital - ISDN subscriber termination. DSL has made it possible to significantly increase the throughput of the subscriber telephone line through the use of line codes and the latest methods of correcting the arising distortions. They were developed with the expectation of the ability to operate on existing telephone lines, providing a constant connection to the Internet and without interfering with the work of other subscriber devices: telephone, fax.
Today the DSL family includes more than a dozen technologies. The main ones include: ADSL, HDSL, IDSL, MSDSL, PDSL, RADSL, SDSL, SHDSL, UADSL, VDSL.
ADSL connection
The peculiarity of ADSL technology is asymmetric distribution of channel bandwidth between outgoing and incoming traffic. Basically, when working with a computer, the user receives information, so the incoming traffic is provided with a wider frequency band - from 138 kHz to 1.1 MHz (from the selected interval from 26 kHz - 1.1 MHz.
ADSL technology provides the maximum speed of reception and transmission of 24 and 3.5 Mbit / s, respectively, with a maximum distance from the PBX of no more than 5.5 km. The quality of the telephone cable also plays a role.
The use of ADSL modems requires the installation of special equipment on each PBX; nevertheless, this technology is the most widespread in the world today. In some European countries (Finland, Great Britain), it is the standard and provides the general population with inexpensive and fairly fast Internet.
