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Tech Hurdles Remain for Digital Switch

The switch to digital TV coming Feb. 18, 2009, was sold to Washington policymakers in part on the promise of those ultra-sharp HD pictures. But as the deadline for the conversion of the nation's 1,700 or so full-power TV stations to that digital system draws near, the focus is on ensuring that viewers can get a DTV signal at all.

HD is “second base,” says David Donovan, head of the Association for Maximum Service Television, which advocates spectrum policy issues for broadcasters. “We're still trying to make sure this transition happens.”

Donovan says the mobile unlicensed device issue—dubbed either “white spaces” or “interference zones,” depending on whom you talk to—is a big threat to those pretty HD pictures. He says testing has shown that the devices can interfere with both cable and broadcast HDTV reception.

A majority of FCC commissioners have said they favor allowing the devices, but want assurances they won't interfere with broadcasters. The FCC is still testing the so-called “spectrum-sensing devices,” which include laptops and PDAs, while broadcasters continue to lobby hard against them.

Conversion Confusion

One potential regulatory knot that is slowly getting untangled is how cable will retransmit and downconvert a broadcaster's HDTV signal. In September, the commission ruled that cable operators must carry broadcasters' HD signals in HD, and in at least as high a resolution as they carry other programming, which ensures that cable operators do not favor their own HD programming over that of broadcasters. Operators also must make those digital HD signals viewable to analog subscribers by converting them, though just how they do that is one of those devilish details.

The FCC set cable's mandatory carriage requirement to sunset in three years, mirroring a voluntary three-year carriage agreement the cable industry was prepared to offer. The FCC has indicated that cable operators will be responsible for providing the downconverted signal until 2012 and are thus required to buy any necessary decoding equipment. But according to both broadcast and cable engineers, some stations may wish to perform the downconversion themselves, for quality reasons, and then pass it along via fiber to cable operators.

Another question is what aspect ratio the downconverted content will appear in: the 4:3 aspect ratio commonly found on analog sets, or the 16:9 widescreen aspect ratio used by HDTV broadcasts. A 16:9 image would appear as a letterboxed picture on an older 4:3 set, which could inspire consumers to buy a new HDTV set—or simply anger them by leaving the top and bottom of their TV screen blank. A 4:3 image would fill their existing screen, but would never give a hint of HDTV's promise.

“We're no longer worried about the HD signal getting to home,” notes Ira Goldstone, chief technology officer for Tribune Broadcasting. “The question is, What is the best way to present to non-HD homes? That's still unclear, and there are a lot of questions there.”

How to implement the downconvert isn't just a must-carry issue. It is also being discussed by cable operators who carry local broadcast signals under retransmission-consent agreements, which are common among large stations.

“It's a point of serious concern and conversation, and it is and will be part of retransmission agreements underway,” says Ardell Hill, SVP of broadcast operations for Media General. Hill adds that cable operators and broadcasters are on the same page in wanting to avoid angry phone calls come Feb. 18, 2009.

“Neither the cable MSOs nor the broadcasters have anything but a desire to not irritate the consumer with a picture that is less than satisfying,” says Hill. “If a guy has a 12- or 13-inch set sitting in his kitchen or on the bar, and all of sudden we drop a 16:9 picture into that set that is going to be letterboxed, he is going to be looking at an 8-inch picture. He's not going to be thrilled and happy with that type of arrangement, and I don't think cable operators want him angry any more than broadcasters do.”

The National Cable & Telecommunications Association declined to comment on the downconversion issue, noting that the FCC still hasn't released its digital must-carry order. The commission should rule soon.

Testing in Boston

Figuring out which aspect ratio to go with isn't easy, says Marty Faubell, VP of engineering for Hearst-Argyle Television. WCVB, the Hearst-Argyle station and ABC affiliate in Boston, has been producing its newsmagazine Chronicle in HD for years, and has experimented with—and debated over—offering both 4:3 and letterboxed 16:9 downconverted versions for analog broadcasts. Both aspect ratios resulted in disgruntled SD viewers.

“It's not that you can win, but which way you lose less,” quips Faubell.

While the FCC has yet to issue detailed rules on digital must-carry, how broadcasters and cable operators work out the downconvert issue may have more to do with their existing infrastructure. A number of large-market stations already provide fiber feeds of their standard-def signals to cable operators and could theoretically continue to do so, though they would no longer be broadcasting that signal after Feb. 17, 2009. Other stations might be content to simply broadcast a single, over-the-air HD signal and let cable handle the downconversion.

About half of Media General's 21 stations currently provide fiber feeds of their analog signals to local cable headends. Maintaining the status quo, at least initially, might make sense, says Hill.

“It would be great post-transition if we would be in the mode, for some period of time, where we continue to provide what we do today,” he says.

A high-quality downconverter that a broadcaster would buy might cost $8,000, while a capable headend downconverter might cost $1,000. Goldstone says there are professional off-air receiver decoders available for around $1,500 that could output both HD and downconverted SD signals. Theoretically, an operator might be able to perform the downconvert with a simple, consumer-grade $80 off-air digital-to-analog converter box, though engineers aren't optimistic about what the quality of such a picture would be.

Dave Converse, VP of engineering for the ABC Owned Television Stations, says he has been approached by cable technology consortium CableLabs to discuss the “end-of-analog scenario” and options such as continuing to provide a 4:3, standard-def picture to headends, either via fiber or microwave link. But Converse says the technical details of how stations and headends handle the downconvert will have to wait until the FCC rules.

Says Converse: “We can't solve the technical questions or answer the question of who's going to pay for it until we figure out what are the rules of engagement.”