xDSL – digital subscriber line
xDSL provide digital subscriber line (DSL) connectivity in a system-on-chip platform. The term xDSL refers collectively to all types of digital subscriber lines. An xDSL chip is a generic term for all forms of DSL service spanning transmission speeds from 128 kbps to 52 mbps. DSL service connection takes place between equipment of the subscriber and the telephone exchange. A protocol is used between the exchange and an internet service provider. A broadband DSL enables the delivery of services at higher data rates and enhances the value for the individual or corporate user. Selection of the DSL provider is based on a combination of a number of factors such as price, dependability and service, DSL hardware, email accounts, and networking. DSL router chips enable connections of shared communication between different computer equipment where computers attached to the shared routers can access the same printers, files, or an internet connection. There are many types of xDSL chips. Examples include SDSL, HDSL, and ADSL. SDSL is a single-line version of HDSL, transmitting T1/E1 signals over a single twisted pair, and able to operate over the plain old telephone service. HDSL is simply a better way of transmitting T1/E1 over copper wires, using less bandwidth without repeaters. It transmits two separate data streams with much more bandwidth devoted to the downstream leg to the customer than returning. ADSL provides greater volume of data flow in one direction. Its downstream rates start at 256 kbit/s and typically reach 8 Mbit/s within 1.5 km. Other xDSL chips are commonly available.
xDSL chips use the same copper-based lines that are used in making and receiving telephone calls. To send data at high speeds carriers use the lines at higher frequencies that telephone service does not need. DSL modems are connected at both ends of the line. The modems digitally divide a telephone line into three channels for telephone traffic, for upstream data from a computer to the Internet, and for downstream data traffic from the Internet to a computer. The modem transmits duplex (transferring data in both directions simultaneously) at DSL speed of 160 kbps over copper lines of up to 18,000 feet. DSL modem uses twisted-pair bandwidth from 0 to approximately 80 kHz, which precludes the simultaneous use of analog telephone service. xDSL chips are installed at both ends of a line, to convert a telephone line into a high speed DSL.