What is DSL

What is DSL?
DSL stands for Digital Subscriber Line. Digital Subscriber Line technology allows for the transmission of information (voice, video and data), over existing copper telephone lines at incredible speeds. DSL provides dedicated bandwidth that can be up to 4 times faster than a T1 connection. DSL uses your ordinary phone line and you are always connected. There's no dialing up or waiting caused by busy signals. There are various forms of DSL, which are as a group referred to as xDSL.

ADSL (Asymmetric Digital Subscriber Line) is quickly becoming the most popular form of xDSL. ADSL supports up to 8 Mbps bandwidth for downloading and up to 1 Mbps for uploading. The asymmetrical nature of ADSL technology makes it ideal for Internet/Intranet surfing, video-on-demand, and remote local area network (LAN) access. Users of ADSL typically download more information than they send.

ADSL requires a voice/data splitter, commonly called a POTS Splitter (Plain Old Telephone Service) to be installed at the consumer's home or business location. The splitter separates voice from data transmissions. For simultaneous use of the telephone and data access, additional phone wires may need to be installed at your location. Full rate ADSL provides service up to a maximum range of 12,000 feet (about 2.0 miles) from the telecommunication provider company's central office to the end-user.

ADSL Lite technology often called Splitterless, G.lite or Universal ADSL and now also known as G.992.2 does not require a POTS splitter to be installed at the consumer's home or business. ADSL Lite provides bandwidth downstream up to 1.5 Mbps and upstream up to 512 kbps. ADSL Lite provides service up to a maximum range of 12,000 feet (about 2.0 miles) from the central office.

SDSL (Symmetrical Digital Subscriber Line) delivers high-speed data networking over a single-pair of copper phone lines, at the same speed in both the upstream and downstream directions. Speed ranges from 160 Kbps up to 1.544 Mbps at a maximum range of 15,000 feet (about 2.8 miles). SDSL is ideal for business applications that require identical downstream and upstream speeds such as video conferencing or collaborative computing as well as similar applications appropriate for ADSL technology. SDSL uses the same kind of line-modulation technique employed in ISDN, known as 2B1Q.

HDSL (High bit-rate Digital Subscriber Line) delivers high-speed data networking up to 1.544 Mbps over two copper pairs and up to 2.048 Mbps over three pairs at a maximum range of 20,000 feet (about 3.8 miles) from a central office. It is similar to SDSL and has symmetrical transmission capabilities. Most T1 lines installed today utilize this technology.

IDSL (ISDN Digital Subscriber Line) provides symmetric download and upload speeds from 64 to 144 Kbps on a single pair of copper wires. The maximum range of IDSL from a central office is 39,600 feet (about 7.5 miles), but this can be doubled with a mid-span "U" loop repeater. IDSL uses 2B1Q line coding, the same kind of line-modulation technique employed in SDSL, and ISDN.

VDSL (Very high bit-rate Digital Subscriber Line) is the fastest xDSL technology, delivering downloads up to 13-52 Mbps and uploads at 1.5 to 2.3 Mbps over a single pair of copper wires. However, VDSL is limited to a maximum range of 1,000 to 4,500 feet (about .2-.9 miles) or 1.6-7.2km from the central office, depending upon the speed.

DSL connections utilize a bandwidth of up to 1.2 MHz and enable data speed from 128 Kbps up to 6.144 Mbps.

DSL stands for Digital Subscriber Line. Local Exchange carriers currently use a single unshielded twisted pair of wire for transmitting voice, which requires 300-3,400 Hz of bandwidth on the local loop (between Central Office and Customer Premises). The wires are, however, capable of carrying information at much higher rate when modern digital processing techniques are deployed. The same pair of wires are used successfully worldwide to provide ISDN services yielding up to 128 Kbps. The explosive growth in Internet access, remote LAN access and telecommuting demand data rates that are a lot higher than what is available today over the existing pair of wires.

Back to top