How Does DSL Work?
DSL turns your existing phone line into a three-channel data delivery system One channel transmits voice and fax services, regardless of whether you are accessing the Internet. The remaining downstream and upstream channels carry information to and from the Internet. There are modems at each end of the phone line. One modem is in your location, while the other is in the telephone company central office. Working together, the modems provide a dedicated connection that avoids the need to dial-up for access. The modem in the Verizon Central Office points your Internet traffic to the DSL network and on to the Internet. You just click on the desktop browser icon to get online!
• A: DSL is based on Asymmetric Digital Subscriber Line (ADSL), a super-fast modem technology that can provide data transmission at significantly higher speeds than your standard 56K modem. DSL transforms standard twisted-pair copper telephone wires into a high-speed digital pipe. Since this wiring is already in place in most homes and offices, millions of users can switch to DSL service without the need to run new wires to your location. DSL is designed to take advantage of the portion of the bandwidth not used for voice calls. DSL technology splits your phone line into three information channels. One carries data at high speeds from the Internet to your home computer. Another channel transports data at moderate speeds from your home computer to the Internet. The third channel handles regular phone calls and faxes. You’ll be able to surf the Internet while making phone calls or sending a fax. Your regular phone line will continue to work in the event that a power failure affects your
How a DSL connection works is quite similar to how a telephone works it also makes use of a copper wire. These telephone copper wires have extensive space, and it can carry more than your telephone conversation. It has a large bandwidth, or a range of frequencies, than that is required for a voice telephone call. DSL then makes use of these spaces to bring information visible on the line without disturbing the conversations on the telephone. The complete plan of DSL is just to match specific frequencies to tasks at hand. To understand how DSL works, you must need to understand how a telephone line works first or to telephone professionals, the POTS or Plain Old Telephone Service. Traditional phone service was created to let you exchange voice information with other phone users and the type of signal used for this kind of transmission is called an analog signal.
DSL utilizes more of the bandwidth on copper phone lines than what is currently used for plain old telephone service (POTS). By utilizing frequencies above 3200Hz, DSL can encode more data to achieve higher data rates than would otherwise be possible in the restricted frequency range of a POTS (Plain Old Telephone System) network. In order to utilize the frequencies above the voice audio spectrum, DSL equipment must be installed on both ends and the copper wire in between must be able to sustain the higher frequencies for the entire route. This means that bandwidth limiting devices such as loading coils must be removed or avoided.
Voice uses only a small fraction of the range of frequencies that a copper wire carry. Using frequency ranges outside of that used by voice (e.g. ADSL) or even using the whole frequency range of the wire (e.g. SDSL), can considerably increase the bandwidth of the circuit. By using special frequency filters at the local telephone exchange, and sometimes at the customer’s end too, two or more additional data bands can be detected and separated to create an “upstream” data signal and a “downstream” data signal.
