History of Computers - DSL
Page created by Kate Clarke
DSL[1] is a high-speed Internet service like cable Internet. DSL provides high-speed networking over ordinary phone lines[2] using broadband modem technology. DSL technology allows Internet and telephone service to work over the same phone line without requiring customers to disconnect either their voice or Internet connections.[3] DSL is an internet system used mainly in homes and small businesses. DSL is also called xDSL and is used to refer to the different #Types of DSL In order for DSL to work properly, the router needs to be close enough to a telephone company which offers DSL services. If this is the case, a user may be able to receive data at rates up to 6.1 megabits (millions of bits) per second (of a theoretical 8.448 megabits per second), enabling continuous transmission of motion video, audio, and even 3-D effects.[4]
Contents
Overview
How it Works
A traditional phone service (or POTS[5] is able to connect one's home or small business to a telephone company office through copper wires called "twisted pairs"[6] The traditional phone service was initially created to allow a person to exchange voice information wither other phone users, using an analog signal.analog signal. A phone works by converting acoustic signals and converting them into an electrical equivalent in terms of volume[7] and pitch[8] Since a telephone company's signaling is already set up for this type of analog wave transmission, it is easier to exchange information with the telephone company. This is why a computer needs a modem, so it is able to demodulate[9] the analog signal.
The copper wires used to connect a phone line have a lot of room and can support more than telephone conversations -- they are capable of handling a much greater bandwidth[10] than that demanded for the voice. DSL takes advantage of this "extra capacity" in order to carry information through the wire without disturbing a telephone conversation. This entire process is based off of matching particular frequencies to particular tasks. Digital Subscriber Line is a technology that assumes digital data does not require change into analog form and back. Digital data is transmitted to your computer directly as digital data and therefore is able to take advantage of the leftover space on the copper wire.
Types of DSL
ADSL
The variation called ADSL[11] is the form of DSL that will become most familiar to most users. Many homes and small business users are connected to an ADSL line. ADSL divides up the available frequencies in a line on the assumption that most Internet users look at, or download, much more information than they send, or upload. Under this assumption, if the connection speed from the Internet to the user is three to four times faster than the connection from the user back to the Internet, then the user will see the most benefit most of the time. See more about ADSL
CDSL
CDSL[12] is a variation of DSL, trademarked by Rockwell International Corporation that is somewhat slower than ADSL. CDSL has the advantage of not requiring a 'splitter' on the user's end of the DSL. However, Rockwell no longer provides information about CSDL at its Web site and does not appear to be marketing it.
Significance
Links
- DSL Wiki
- History of DSL
- Fast Guide to DSL
- How Stuff Works Article
- About DSL
- Types of DSL
- Rockwell Corp Definition
References
- ↑ Digital Subscriber Line
- ↑ Specifically, copper telephone lines that exist in today's phones.
- ↑ Definition found at About DSL
- ↑ Information found at Fast Guide to DSL
- ↑ Plain Old Telephone Service
- ↑ Copper wires that are wound around each other
- ↑ Signal amplitude
- ↑ Frequency of wave change
- ↑ Converting analog signals back into digital signals
- ↑ Range of frequencies
- ↑ Asymmetric Digital Subscriber Line
- ↑ Consumer DSL
