We explain what ADSL is and the fundamentals of this technology. In addition, what is it for, characteristics, advantages and disadvantages.
What is ADSL?
ADSL (from the acronym in English Asymmetric Digital Subscriber List which translates Asymmetric Digital Subscriber Line) is a type of digital data transmission technology and Internet access, which consists of the transmission through symmetric pairs of copper telephone line. This is a method of access to Internet through the telephone line (Switched Telephone Network, PSTN) that does not 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 (of the net to the computer) and charging (from computer to the network) are not coincident, but rather the first is greater than the second. Ultimately, most of the users They receive more information from the Internet than they emit.
For ADSL to work, it is necessary to have a telephone line and a modulation system that separates the frequencies of the voice and the data, by installing discriminating filters (called splitters, microfilters or DSL filters) and an ADSL router provided by the business that provides the service.
This type of urban copper wiring was traditionally implemented, but in the final decades of the 20th century it was gradually replaced by fiberglass, a material that offered better conduction and performance, thus making room for even better methods of transmitting digital information, such as cable modem or Ethernet.
What is ADSL for?
Like other digital transmission systems, ADSL serves as a digital data transmission channel and Internet connection.
This means that it is a virtually unlimited source of information and online services, with all that this implies. This connection method was key in the massification of the Internet in homes and urban environments during the 1990s.
Characteristics of ADSL
In an ADSL connection, three independent transmission lines are established:
- Data sending channel. Where the user information will be sent to the Internet (upload or load).
- 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 management 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 TV by subscription (cable TV) and high quality video (HD).
Advantages of ADSL
Each subscriber receives an independent and non-transferable service direct to their home.
- It does not occupy the telephone line. This represents an advantage when installing the service in homes and businesses, as it allows autonomy of both services, which is impossible with the dial-up method.
- Use the infrastructure traditional. It does not require novel and extensive investments or large works, since it takes advantage of traditional copper wiring.
- Outperforms dial-up connection. It offers a much better speed/price ratio than dial-up methods, which in addition to occupying the telephone line generally go at 56 kps, while ADSL can reach 4mbps (70 times faster).
- Allows core and custom circuits.Since it uses telephone wires, each subscriber receives a separate, non-transferable service direct to their home or office.
Disadvantages of ADSL
- It does not work on all telephone lines. It is not enough to have a telephone connection via copper wiring to use ADSL, since this technology It has a limit of 3km in line length from the broadcasting center.
- It demands copper quality. 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 exchange and fluctuations in the flow of the service.
- It is much inferior to fiber optics. Fiber optic connections far exceed ADSL in stability and speed.
VDSL
VDSL or VHDSL (from the acronym in English Very High-bit-rate Digital Subscriber Line or Very High Transfer Rate Digital Subscriber Line) is a type of Broadband Internet connection with much higher performance than ADSL, representing its evolution or superior 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.