According to abbreviationfinder, ADSL stands for Asymmetric Digital Subscriber Line (“Asymmetric Digital Subscriber Line”). ADSL is a type of DSL line . It consists of an analog transmission of digital data supported by the symmetrical pair of copper that carries the conventional telephone line or subscriber line, as long as the length of the line does not exceed 5.5 km measured from the Telephone Exchange, or there are no other services on the same cable that may interfere.
It is a Broadband Internet access technology, which implies a higher data transfer speed than a traditional modem connection, since the Modem uses the voice band and therefore prevents the voice service while it is being used and vice versa. This is achieved by modulating the data signals in a higher frequency band than that used in conventional telephone conversations (300-3400 Hz), a function performed by the ADSL Router. To avoid distortions in the transmitted signals, it is necessary to install a filter (called a splitter or discriminator) that is responsible for separating the conventional telephone signal from the modulated signals of the ADSL connection.
This technology is called asymmetric because the download capacity (from the network to the user) and the data upload capacity (in the opposite direction) do not coincide. ADSL technology is designed so that the download (download) capacity is greater than the upload capacity, which corresponds to the use of the internet by most end users, who receive more information than they send (or download). more than they go up).
Advantages and disadvantages of ADSL technology
ADSL presents a series of advantages and also some disadvantages, with respect to the telephone connection to the Internet through a modem.
- It offers the possibility of talking on the phone while browsing the Internet, since, as indicated above, voice and data work in bands separated by the ADSL technology itself and by physical filters (splitters and microfilters).
- It uses an existing infrastructure (that of the basic telephone network). This is advantageous, both for the operators who do not have to face large expenses for the implementation of this technology, and for the users, since the cost and the time it takes to have the service available is less than if the operator had to undertake works to generate new infrastructure.
- It offers a connection speed much higher than that obtained by dialing up the Internet. This is the most interesting aspect for users. In the vast majority of scenarios, it is the technology with the best speed/price ratio.
- Each Circuit between subscriber and exchange is unique and exclusive for that user, that is, the copper cable that leaves the subscriber’s home arrives at the exchange without having been added, and therefore avoids shared channel bottlenecks, which does occur in other technologies such as cable.
- Not all telephone lines can offer this service, because the quality requirements of the pair, both noise and attenuation, due to distance from the exchange, are stricter than for the basic telephone service. In fact, the theoretical limit for acceptable service is 5.5 km of line length.
- Due to the fact that these lines are required, the service is not cheap in countries with few or poor infrastructures, especially if we compare it with the prices in other countries with more advanced infrastructures.
- The quality of the service depends on external factors such as cable interference or distance from the central unit, as there are no signal repeaters between it and the end user’s modem. This causes the quality of the service to fluctuate, causing in some cases outages and/or a decrease in flow. There are thousands of sources of electromagnetic interference from water to electric motors through the customer’s internal installations of power cables or piped music. This problem does not exist in optical fiber where light is transmitted protected by an opaque cover, so there is no interference.