What is ADSL

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The ADSL (Asymmetric Digital Subscriber List that translates Asymmetric Digital Subscriber Line) is a type of technology for the transmission of digital data and access to the Internet, which consists of the transmission through symmetric pairs of telephone line copper. That is, a method of accessing the Internet through the telephone line (Switched Telephone Network, PSTN) that doesn't prevent the regular use of the line for calls.

ADSL is a type of Broadband connection, whose name comes from the fact that the download capacity (from the network to the computer) and the upload capacity (from the computer to the network) don't coincide, but rather that the former is greater than the second. After all, most Internet users receive more information than they emit.

For ADSL to work, it's necessary to have a telephone line and a modulation system that separates the frequencies of voice and data, by installing discriminating filters (called splitters, microfilters or DSL filters) and an ADSL router. provided by the company providing the service.

This type of urban copper cabling was traditionally implemented, but in the late twentieth century they were gradually replaced by fiberglass, a material that offered better conduction and performance, thus making room for even better digital information transmission methods, such as cable modem or Ethernet.

What is ADSL for?

Like other digital transmission systems, ADSL serves as a digital data transmission channel and connection to the Internet.

This means that it's a virtually unlimited source of information and services online, with all that that implies. This connection method was key in the massification of the Internet in homes and urban environments during the 1990s.

ADSL features

In an ADSL connection, three independent transmission lines are established:

- Data sending channel. Where the user's information will be sent to the Internet ( upload or upload).
- Data reception channel. Where the information will be received from the Internet ( download or download). It will be the widest of the three channels.
- Regular telephone service channel. Where the phone calls will be transmitted.

This separation allows a differentiated handling of data and transmission impulses, and can even be improved in the versions known as ADSL2 and ADSL2 +, in which a channel is also received for the transmission of subscription television (cable TV) and video. high quality (HD).

ADSL advantages

- It doesn't occupy the telephone line: This represents an advantage when installing the service in homes and companies, since it allows the autonomy of both services, something impossible with the dialing method.
- It uses the traditional infrastructure: It doesn't require new and extensive investments or large works, since it takes advantage of traditional copper wiring.
- Beats dial-up connection: It offers a much better speed / price ratio than dialing methods, which in addition to occupying the telephone line usually go to 56 kps, while ADSL can reach 4mbps (70 times faster).
- It allows central and personalized circuits: Since it uses telephone cables, each subscriber receives an independent and non-transferable service direct to their home or office.

Disadvantages of ADSL

- It doesn't operate on every phone line: It's not enough to have a telephone connection by copper cabling to use ADSL, as this technology has a maximum line length of 3km from the central station.
- It demands quality of copper: In countries where this material is expensive or scarce, the service may not be as economical as in others.
- It depends on external factors: The quality of the service is subject to the quality of the cables, the distance from the plant and fluctuations in the flow of the service.
- It's far inferior to fiber optics: Fiber optic connections far outperform ADSL in stability and speed.


VDSL or VHDSL ( Very High-bit-rate Digital Subscriber Line or Digital Subscriber Line with very high transfer rate) is a type of Broadband Internet connection with much higher performance than ADSL, representing its evolution or higher step.

This technology consists of the use of four channels for data transmission: two for downloading and two for uploading, substantially increasing the transmission power of the service.

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