Type of DSL And Modem
Type of DSL And Modem
DSL uses the existing phone line and in most cases does not require an additional phone line. This gives "always-on" Internet access and does not tie up the phone line. There won't be any more busy tone from phone line, no more dropped connections, no more waiting for someone in the household to get off the phone. DSL offers users a choice of speeds ranging from 144 Kbps to 1.5Mbps. The DSL speed is 2.5x to 25x times faster than a standard 56Kbps dial-up modem. This digital service can be used to deliver bandwidth-intensive applications like streaming audio/video, online games, application programs, telephone calling, video conferencing and others high-bandwidth services within smaller time frame.FPRIVATE "TYPE=PICT;ALT=DSl - Network "
DSL Modem
ADSL (Asymmetric Digital Subscriber Line) - ADSL has data rate of .544 to 6.1 Mbps downstream; 16 to 640 Kbps upstream. And the distance limit for this type of DSL is 1.544 Mbps at 18,000 feet; 2.048 Mbps at 16,000 feet; 6.312 Mpbs at 12,000 feet; 8.448 Mbps at 9,000 feet. ADSL is normally used for Internet and Web access, motion video, video on demand, remote LAN access
HDSL (High bit-rate Digital Subscriber Line) - HDSL is the earliest version of DSL to be used for wideband digital transmission within a corporate site and between the telephone company and a customer. The main characteristic of HDSL is that it is symmetrical: an equal amount of bandwidth is available in both directions. For this reason, the maximum data rate is lower than for ADSL. HDSL can carry as much on a single wire of twisted-pair as can be carried on a T1 line in North America or an E1 line in Europe (2,320 Kbps).
IDSL (ISDN Digital Subscriber Line) - IDSL is somewhat of a misnomer DSL modem since it's really close to ISDN data rates and service at 144 Kbps than to the much higher rates of ADSL. IDSL is usually not sold by ADSL providers, is symmetric ("duplex"), with the biggest advantage being the distance it can travel (5-6 miles). Similar to ISDN (128 Kbps) but uses the control channel to increase data rates to 144 Kpbs.
RADSL (Rate-Adaptive DSL) - is an ADSL technology from Westell in which software is able to determine the rate at which signals can be transmitted on a given customer phone line and adjust the delivery rate accordingly. Westell's FlexCap2 system uses RADSL to deliver from 640 Kbps to 2.2 Mbps downstream and from 272 Kbps to 1.088 Mbps upstream over an existing line.
SDSL (Symmetric DSL) - is apparently the same thing as HDSL with a single line, carrying 1.544 Mbps (U.S. and Canada) or 2.048 Mbps (Europe) each direction on a duplex line. It is considered to be the "business grade" DSL because of its symmetric speeds. SDSL is slower than ADSL but usually marketed with Service Level Agreement (SLA) such as the network will be guaranteed up for 99.5%, and there will be a 24-hour response time for every problem.
UDSL (Unidirectional DSL) - is a proposal from a European company. It's a unidirectional version of HDSL.
VDSL (Very high data rate DSL) - is a developing technology that promises much higher data rates over relatively short distances (between 51 and 55 Mbps over lines up to 1,000 feet or 300 meters in length). It's envisioned that VDSL may emerge somewhat after ADSL is widely deployed and co-exist with it. The transmission technology (CAP, DMT, or other) and its effectiveness in some environments are not yet determined. A number of standards organizations are working on it.
xDSL - Refers collectively to all types of Digital Subscriber Lines, the two main categories being ADSL and SDSL.
x2/DSL - is a planned modem from 3Com and US Robotics that supports 56 Kbps modem communication but is upgrade-able through new software installation to ADSL when it becomes available in the user's area. 3Com calls it "the last modem you will ever need."
DSL uses the existing phone line and in most cases does not require an additional phone line. This gives "always-on" Internet access and does not tie up the phone line. There won't be any more busy tone from phone line, no more dropped connections, no more waiting for someone in the household to get off the phone. DSL offers users a choice of speeds ranging from 144 Kbps to 1.5Mbps. The DSL speed is 2.5x to 25x times faster than a standard 56Kbps dial-up modem. This digital service can be used to deliver bandwidth-intensive applications like streaming audio/video, online games, application programs, telephone calling, video conferencing and others high-bandwidth services within smaller time frame.FPRIVATE "TYPE=PICT;ALT=DSl - Network "
DSL Modem
ADSL (Asymmetric Digital Subscriber Line) - ADSL has data rate of .544 to 6.1 Mbps downstream; 16 to 640 Kbps upstream. And the distance limit for this type of DSL is 1.544 Mbps at 18,000 feet; 2.048 Mbps at 16,000 feet; 6.312 Mpbs at 12,000 feet; 8.448 Mbps at 9,000 feet. ADSL is normally used for Internet and Web access, motion video, video on demand, remote LAN access
HDSL (High bit-rate Digital Subscriber Line) - HDSL is the earliest version of DSL to be used for wideband digital transmission within a corporate site and between the telephone company and a customer. The main characteristic of HDSL is that it is symmetrical: an equal amount of bandwidth is available in both directions. For this reason, the maximum data rate is lower than for ADSL. HDSL can carry as much on a single wire of twisted-pair as can be carried on a T1 line in North America or an E1 line in Europe (2,320 Kbps).
IDSL (ISDN Digital Subscriber Line) - IDSL is somewhat of a misnomer DSL modem since it's really close to ISDN data rates and service at 144 Kbps than to the much higher rates of ADSL. IDSL is usually not sold by ADSL providers, is symmetric ("duplex"), with the biggest advantage being the distance it can travel (5-6 miles). Similar to ISDN (128 Kbps) but uses the control channel to increase data rates to 144 Kpbs.
RADSL (Rate-Adaptive DSL) - is an ADSL technology from Westell in which software is able to determine the rate at which signals can be transmitted on a given customer phone line and adjust the delivery rate accordingly. Westell's FlexCap2 system uses RADSL to deliver from 640 Kbps to 2.2 Mbps downstream and from 272 Kbps to 1.088 Mbps upstream over an existing line.
SDSL (Symmetric DSL) - is apparently the same thing as HDSL with a single line, carrying 1.544 Mbps (U.S. and Canada) or 2.048 Mbps (Europe) each direction on a duplex line. It is considered to be the "business grade" DSL because of its symmetric speeds. SDSL is slower than ADSL but usually marketed with Service Level Agreement (SLA) such as the network will be guaranteed up for 99.5%, and there will be a 24-hour response time for every problem.
UDSL (Unidirectional DSL) - is a proposal from a European company. It's a unidirectional version of HDSL.
VDSL (Very high data rate DSL) - is a developing technology that promises much higher data rates over relatively short distances (between 51 and 55 Mbps over lines up to 1,000 feet or 300 meters in length). It's envisioned that VDSL may emerge somewhat after ADSL is widely deployed and co-exist with it. The transmission technology (CAP, DMT, or other) and its effectiveness in some environments are not yet determined. A number of standards organizations are working on it.
xDSL - Refers collectively to all types of Digital Subscriber Lines, the two main categories being ADSL and SDSL.
x2/DSL - is a planned modem from 3Com and US Robotics that supports 56 Kbps modem communication but is upgrade-able through new software installation to ADSL when it becomes available in the user's area. 3Com calls it "the last modem you will ever need."
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