DSL, also known as a Digital Subscriber Loop or a Digital Subscriber Line, is one of the more common methods of accessing the Internet through a broadband connection. DSL connections are accessed through telephone lines and, in almost all cases, set up by local telephone providers. Though DSL generally does not require special wiring in order to operate correctly, there are some occasions where new wiring must be run or special filters used in order to prevent a bleed-over between the telephone line and data of the DSL connection, which would result in interference for both components.
History
DSL originated in the late 1980s as a result of work done by Bellcore (one of the "Baby Bell" companies, now known as Telcordia Technologies), although the basis for DSL technology was actually created much earlier. Claude Shannon wrote the scientific paper, "A Mathematical Theory of Communication," in 1948, describing the basis for information transfer by electronic means and laying the groundwork for information technologies that would follow. The work that Bellcore did based upon this paper placed a digital signal over the standard analog signals transmitted by their telephone lines, using a twisted pair of cables to transmit this digital signal. As twisted-pair wiring became more common and phone lines began converting to the more modern lines in use today, the availability of DSL spread rapidly to large cities and then to smaller cities and towns.
Function
DSL wiring uses two matching sets of wires, though it is possible for a DSL connection to operate over a single set of wires, provided a filter is used to separate voice communication from the digital packets sent through the connection. These wires are set up the same as standard telephone wires, although they exist in twisted pairs so that the digital signal of the DSL connection can be sent through one pair while telephone communications can be sent through the other.
Features
DSL's twisted-pair wiring is designed to transmit both voice and data communications without the bleed-over effect that occurs when trying to use a single set of wires. When possible, the wire connected to the DSL modem is done as a single line from the house or apartment's main telephone connection; this is done to prevent a weakening of data signals that can occur if there are too many splits in the line the DSL connection travels. A strong DSL connection can produce Internet connection speeds many times faster than a standard dial-up connection, with speeds that may match or exceed those offered by some cable Internet connections.
Benefits
The main benefit of a DSL connection on twisted-pair wiring is a fast Internet connection without the need for special filters to separate voice and data signals. Other benefits include having an Internet connection that is "always on" instead of needing to connect each time and being able to rely get reliable Internet service from a company with whom you already have a relationship. In most cases you will not need to have any additional wiring run, since many houses and apartments already feature the twisted-pair wiring that DSL providers recommend.
Considerations
Not all homes and apartments have twisted-pair wiring, so in order to use DSL you either need to have new wiring installed or you use a filter for your phone connection to keep telephone conversations from interfering with your Internet connection. Another consideration is exactly how far your home is from the closest telephone trunk line. The farther away you are, the slower your DSL connection will be, due to what's known as "data degradation." Depending on where you live and the telephone service that you use, DSL might not even be available as a broadband option as yet (since not all telephone companies offer DSL connections.)
Tags: twisted-pair wiring, Internet connection, digital signal, sent through, data signals