Coming full circle: Vendors, telcos revive DSL video strategy

With high-speed Internet access as the latest Holy Grail in the telecom industry, digital subscriber line technology appears to be telcos' clearest path to the promised land.

However, a number of vendors and small Independent telcos are bringing DSL back to its original purpose as a platform for delivering video over copper. One of the most recent attempts comes from mPhase Technologies. The Norwalk, Conn.-based company recently completed a demonstration with DTC Communications that transmitted broadcast-quality, MPEG 2 full-motion pictures over 9000 feet of a single twisted pair.

Using a digital video disc player as the source, DTC, a 17,000-line Independent operating in DeKalb County, Tenn., chose a random copper pair on which to send video while simultaneously operating its normal switching gear.

"We found a loop that was about 4500 feet, so we looped it out and back so we could look at the screens from two points," said Wayne Gassaway, general manager of DTC, which has been working with mPhase for about two years on the video project.

With two televisions to monitor picture quality, the demonstration proved DSL could transmit very high-quality pictures over copper, Gassaway said. "The only thing I could tell was when the picture shifted from one scene to another, there was a fraction of a second delay. And we wouldn't have noticed if the televisions weren't side by side."

Although DTC isn't offering cable service yet, the demonstration may open the door to new business, Gassaway said. In particular, the company's service territory includes many areas not reached by traditional cable providers. "It's not just a temporary or patch network to get to cable. It's part of a strategic plan to expand broadband," he said.

During the test, mPhase also used an Apple Newton to perform an on-line credit card transaction.

"The reason we did that is we wanted an extended time frame within Wayne's facilities so he could watch the screen to see if there were any artifacts," said Thomas Murphy, chief technical officer of mPhase. "The bandwidth separation was excellent."

Born out of defense contractor Microphase, mPhase is still testing the platform and is using the Georgia Tech Institute for its manufacturing expertise and as a consultant on some network architecture issues. Combined, the companies expect to have a platform that will allow telcos to deliver up to 256 channels of video, high-speed Internet access and voice over a single twisted pair. Just as important, the company claims the platform will be able to deliver service beyond 18,000 feet.

Key to the technology is the use of sophisticated filters that pick up degraded signals and essentially reconstitute them.

"In early designs, that's an area where other people had faltered," Murphy said. "We did things that are proprietary but that will still fit into the standard. Our whole approach originally was to design something that would work on DS-3, realizing the [asynchronous transfer mode] facilities would not be available to every company."

The company also is using repeater technology that borrows from the defense industry. The result is a platform that can push the capability of DSL well beyond the current 18,000 foot limit. "In this case, our ultimate goal is probably that we will have a repeater capability that will exceed 30,000 feet. And based on the techniques we're using, I don't see a problem exceeding that by 5000 feet."

For now, mPhase is concentrating its efforts on demonstrating the system to telcos and proving it can use existing infrastructure to transmit high-quality video. "Frankly, we don't think people realize the opportunity this provides," said Murphy.