ADC Repeater Doubles Distance of HDSL2 Modem

WASHINGTON (01/27/2000) - ADC Telecommunications is doubling the distance its two-wire, high-bit-rate digital subscriber line technology can reach, which will enable more customers to get HDSL2 services.

The company announced last week at ComNet 2000 a repeater for its Sonoplex HDSL2 customer gear and carrier switching-office equipment.

The repeater sits in the middle of a long line between HDSL2 modems and regenerates the dying HDSL2 signal, which peters out as lines lengthen. Without a repeater, customer sites must be within 12,000 feet of the switching office.

The repeater pushes that distance to 24,000 feet.

That is key to customers interested in the T-1 replacement technology because a T-1 can also be repeated. HDSL2 must have the extended reach to compete, says Ron Westfall, an analyst with Current Analysis in Sterling, Va. He says customers and carriers should be attracted to HDSL2: customers because HDSL2 is virtually indistinguishable from T-1 service, and carriers because it requires just two wires compared to a T-1's four.

HDSL2 will also help make high-bandwidth dedicated services more available because it doesn't disrupt other services on nearby wires in carrier cables.

Symmetric DSL (SDSL), a symmetric service like HDSL2 that operates at 768K-bps compared to HDSL2's 1.5M-bps, is disruptive to asymmetric DSL (ADSL), which operates at a top speed of 8M-bps. "So far disruption hasn't shown up as a problem because DSL has not reached critical deployment levels with multiple DSL services in the same cable," Westfall says.

The ADC gear can be powered over the phone line that carries the service, so if the customer suffers a power failure, the HDSL2 service should still work, just as a regular phone keeps working when the electricity goes out.

To make its gear more attractive to carriers, ADC plans to participate in an interoperability forum at the University of New Hampshire. The goal is to produce HDSL2 modems made by different vendors working together on the same phone line.

Also chasing interoperability in New Hampshire, Adtran, Inc. says its HDSL2 gear, H2TU-C switching office gear and H2TU-R customer site equipment, have proven interoperable with a prototype HDSL2 modem built around chips made by Globespan. Adtran uses the Globespan chips.

Vendors say it is easier to develop interoperability among products that are based on the same chips.

ADC makes its HDSL2 gear with Level 1 chips, but plans to switch over to Globespan chips in its next product release, according to Sean Martin, ADC's vice president of marketing.

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