The problems with HDTV..........................................
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High-Definition TV Issues Rattle Engineers
By LESLIE ELLIS
San Antonio -- While as many as 25 broadcasters are gearing up for high-definition television transmissions this year, cable-television engineers are grappling with a long list of technical issues that will face them if they're forced to carry those digital signals.
At the Society of Cable Telecommunications Engineers' recent Conference on Emerging Technologies here, representatives from cable MSOs, the Federal Communications Commission and the National Association of Broadcasters spent the better part of a day on the subject of HDTV, resolving that more questions will exist than answers until must-carry legislation is decided.
Tom Elliot, a visiting executive with Cable Television Laboratories Inc., said one of the many potential issues relates to simple viewership.
"The intelligence that we've gotten is that the consumer-electronics industry expects to build about 100,000 high-definition sets this year, and therein lies a problem," he said. "There's not going to be enough of these sets out there to make meaningful economic sense for anybody."
With fewer eyeballs watching what will likely be a mix of primetime HDTV and multiple standard-definition TV signals from broadcasters, even the broadcasters are faced with a daunting economic challenge, said Art Allison, senior engineer for the NAB.
"It is clear that the additional revenue opportunity doesn't compensate for the [HDTV] investment within a short time, like under five years," Allison said.
Allison added that he has not seen any return-on-investment proposals that look good for broadcast HDTV unless time frames are extended to a 20- to 25-year period. "But without it, we'd become technological dinosaurs -- we'd go out of business completely if we didn't go to digital."
That's why broadcasters in the top 10 markets are scurrying to fill the extra 6-megahertz channel granted to them by the FCC with a mix of HDTV and multiplexed SDTV signals.
It's also why cable operators are already worrying about whether they'll have enough room for the broadcasters' digital load, even on their upgraded networks.
"The question that I need answered is: How much bandwidth do I need in metro markets where I know HDTV is coming? Is 750 MHz enough for a metro market?" asked Tom Jokerst, chief technical officer for Charter Communications Inc.
Other engineers here for the two-day confab echoed Jokerst's sentiments. "In a major market, if we're required to carry broadcasters' HDTV signals, that's at least four 6-MHz channels, or 24 MHz, that I have to set aside," lamented one MSO engineer, who asked not to be identified.
FCC executives on the panel said must-carry decisions will come out later this year. Until then, "I would hope that the broadcasters would talk to the cable operators and make it a dual learning experience on both sides," said John Wong, chief of the engineering and technical services division of the FCC's Cable Services Bureau. "Hopefully, they'll reach some agreement between themselves."
Technically, however, there are already major differences. The broadcasters modulate their digital signals using the 8-VSB (vestigial sideband) method, while cable operators settled on a digital modulation standard known as quadrature amplitude modulation, in either 64-QAM or 256-QAM variations.
If cable operators are required to carry the HDTV signals of the broadcasters -- as opposed to letting owners of HDTV sets place an antenna on top of their home to receive the signals directly -- operators will have to deal with how to reformat the HDTV signal in the headend and through digital set-tops.
Or, as Elliot pointed out, if operators simply pass the HDTV signal through the set-top to an HDTV receiver inside the TV set, content owners will likely worry about "the last 36 inches" of cable between the set-top and the TV.
"They'll be unhappy about the possibility of pirate copies" that could be captured from the data stream over the last, three-foot ride to the TV, Elliot said.
Allison suggested one way to work around cable's potential bandwidth conundrum: placing the few early HDTV signals coming from broadcasters in the "roll-off" region of the cable spectrum.
"That could be a way to stick an 8-VSB signal in a market in the early stages, without having to do much of anything else," Allison said.
But cable engineers grimaced at the idea. "That's been the `don't go there' region for the past 40 years," said Ted Hartson, president of Scottsdale TV Laboratories Inc. and moderator of the digital television panel.
There was one area of consensus about the looming HDTV situation: The must-carry decision will be one that is hotly fought as the year unfolds.
"This is going to be a very complex and, I suspect, very contentious round of negotiations," said Doug Watts, vice president of government affairs for Tele-Communications Inc., who added that TCI would "hotly and vigorously oppose" must-carry regulations for broadcast HDTV and SDTV.
Steve Ross, an attorney with Ross & Hardies, agreed. "It's going to be a bruising battle," he said. |
