xDSL Description

"ISDN, HDSL, ADSL, VDSL and SDSL are all DSL modem technologies designed to operate on telephone wires intended originally for voice-band communication (300Hz to 3.4kHz)....". The ISDN signals reside above the voice band. Upload signaling in the band just above POTS followed by Download signaling above that. The phone is required to have a Low-Pass filter installed to block the DSL information. The rates vary depending on the type of DSL service, and all require a Central Office location near the service. Both sides of the service require a DSL modem.

DSL; Digital Subscriber Line. Or xDSL which refers to any of the DSL types.
ADSL; Asymmetric Digital Subscriber Line [one speed for download and another for upload. ADSL can run up to 18,000 feet [1.544 Mbps (T1)]]
SDSL; Symmetric Digital Subscriber Line. [same speed for upload or download. Uses one wire pair, with no analog phone on the line. SDSL is a single pair version of HDSL. One pair of wires can run up to 9,000ft at 768kbps.]
HDSL; High Data Rate DSL [Same speed for up-load or download. May be 1 or 2 wire pair, with no analog phone on the line. HDSL can run up to 12,000 ft [384 Kbps and 2 Mbps]]
VDSL; Very high-speed DSL [type of ADS, used with incoming fiber to copper junction. VDSL can run at 12.96 Mbps (1/4 STS-1) 4,500 feet.]
RADSL; Rate Adaptive DSL [type of ADS, the rate changes depending on line quality]
IDSL; ISDN DSL [Same speed for up-load and download. Uses one wire pair, with no analog phone on the line. Faster than normal ISDN. IDSL; Basic Rate ISDN can run up to 18,000ft at 144 Kbps.]
ISDN [Integrated Services Digital Network] is a communication standard for sending Voice, Video, and Data over digital or analog telephone lines. Basic Rate (BRI) ISDN consists of two 64-Kbps B-channels and one D-channel for transmitting control information. Primary Rate ISDN consists of 23 B-channels and one D-channel [U.S.] or 30 B-channels and one D-channel [Europe]. The ISDN 64kps rate is based on sampling analog voice lines at 8000 times per second with 8 bits per sample. The 64Kbps channels are called B channels. The 16Kbps channels are called D channels. ISDN is a switched, end-to-end network that allows for simultaneous transmission. With two full duplex digital channels, Basic Rate Interface (BRI) ISDN provides high-speed. 128 kilobits per second (kbps) is typical, up to 512kbps with compression. Primary Rate Interface (PRI) ISDN bundles twenty-three channels together, to provide speeds of up to 1,544 kbps.

DSL Standards Info

ITU; International Telecommunication Union, www.itu.int

ETSI; European Telecommunications Standard Institute, www.etsi.org

Related standard; Ethernet-over-VDSL (EoVDSL)

xDSL Interface IC Vendors

Analog Devices {DSL Products}
Broadcom Corp. {DSL-ADSL/VDSL IC Manufacturer}
Intersil {ADSL xceviers}
LSI Corporation {DSL Products}
Texas Instruments {DSL Line Drivers/Receiver IC Manufacturer}
Transwitch

Digital/Specialized Logic
Refer to Telecom Device Manufacturers

IC Manufacturers {All other device types}

Home
Distributors	Components	Equipment	Software	Standards	Buses	Design	Reference