Slow and Steady Wins in Simulcasts


Cable operators on the front lines of digital-simulcast conversions had plenty of free advice for their brethren during a recent CED magazine Webcast, including some on how to gradually implement the new technology while keeping an eye on plant-quality issues.

“A mass cut-over is not a good idea,” because of the potential spike in service calls, Charter Communications Inc. vice president of advanced engineering Pragash Pillai said.

Implementing a limited geographic or limited quadrature amplitude modulation cut-over makes more sense. “Doing both at the same time is much more efficient,” he said. “You can segment field operations.”


Added Comcast Corp. senior vice president of engineering operations John Donahue: “Plant issues affect digital pictures differently than analog.”

Like Charter, Comcast is using 256 QAM to implement digital simulcast.

But what appears as tolerable “lines” or “snow” in analog results in “tiling” or “freezing” in digital transmissions, he said.

“Marginal issues now become perceptible,” he said.

The good news is most of these issues are related to drops or inside wiring problems that can be fixed quickly and easily, he said. “The impact is relatively predictable.”

Donahue said Comcast is on track to get 75% of its “plumbing” ready for digital simulcast by year-end. The Philadelphia system, where the MSO is now installing low-cost digital set-tops, has already launched.

Pillai said Charter has added Madison, Wis., and St. Louis to Long Beach, Calif., as the MSO’s initial simulcast markets, and to plans to have 7 million homes passed (about 60% of its base) by the end of 2006.

Pillai estimated that simulcast will cost Charter about $20 per home passed. The MSO is creating two fully redundant master encoding facilities for national networks for both its West Coast and East Coast markets. Regional and local services are being encoded locally, he said.


The company is using Gigabit Ethernet transport to remote sites, and uses digital transport throughout its plant, switching back to analog at the edge. That will allow Charter to implement a single digital ad-insertion platform, he said.

In addition to the spectrum savings, Charter has enjoyed other benefits. Digital simulcast allows for a consistent audio level across all channels, Pillai said. Subscribers often complain that channel audio levels vary, sometimes to an annoying degree, as they scroll through the lineup.

“It’s very easy to create programming tiers,” he added.