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Windows on the Web
New on the Net
Speedy ADSL Is Slow to Arrive

-- by James E. Powell

Think isdn is fast? Wait till you see Asymmetrical Digital Subscriber Line (ADSL) modem technology.

Unfortunately, "wait" is the operative word. A standards war may prevent you from boarding this data communications bullet train, as may the steep fare.

ADSL uses existing copper telephone line. The service can provide data-transmission rates of 6Mbps downstream and 640Kbps upstream. That translates to downloads that are nearly 47 times faster than ISDN, and 208 times faster than a 28.8Kbps modem.

Cable modems may offer speeds up to 27Mbps, but your connection speed declines as more users share access to the system. ADSL avoids this problem by using individual telephone lines. ADSL also allows for simultaneous data, voice and fax communications over the same line. Moreover, an ADSL modem is always "on"-you don't have to dial in order to connect to the Internet or to your company's LAN.

Now for the bad news. There's a standards problem: Carrierless Amplitude/Phase Modulation is battling Discrete Multitone for universal acceptance as the line coding standard. And no single modem can support both.

Several trials are being conducted, but companies remain vague about dates for a general roll-out.

One thing's for sure: Speed ain't cheap. Efficient Networks' list price for adapters is expected to be $595; modems with the Ethernet port will cost $1,195. Internet access is also pricey: In the Chicago area, InterAccess will charge $180 per month after a $200 installation fee.

Windows Magazine, August 1997, page 238.

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