What Is DSL?

Date First Published: 19th April 2022

Subtopic: Data Transmission Technologies

Article Type: Computer Terms & Definitions

Difficulty: Medium

Difficulty Level: 5/10

Learn more about what DSL is in this article.

Short for digital subscriber line, DSL is a broadband technology that is used to transmit digital signals over telephone lines. DSL provides point-to-point public network access and the DSL connection is established between the ISP and the home or building.

Users must connect to a DSL ISP in order to access the internet using DSL. The ISP will then provide them with a modem, which can be connected to a router or computer. There are some DSL modems that have built-in wireless routers which allow them to be connected to each other using Wi-Fi.

Note:

DSL is a slower broadband option because it uses copper wires.

How Does DSL Work?

Every time a telephone call is made using a landline, the voice signal is transmitted through low frequencies which range from 0 Hz to 4 kHz. This range is known as the voiceband and it only uses a small part of the frequency range that is supported by copper phone lines. The higher frequencies are used by DSL to transmit digital signals, which range from 25 kHz to 1.5 MHz. DSL filters are used to ensure that the high frequencies do not interfere with the phone calls, since the frequencies can still interfere with phone calls even though they are higher than the highest audible frequency, which is 20 kHz.

History

Originally, DSL was part of the ISDN specification that was introduced in 1984. ISDN was originally being used for point-to-point connections for different types of data connections. ISDN provided a low data speed due to the increasing size of networks as well as interruptions in telephone lines. DSL was introduced after ISDN failed and it began to provide broadband connections over an analogue medium.