Public TV Broadcasters Face Deadline

Multicasting, datacasting foretell new role for stations


Not quite half of the nation's 357 public television stations made the May 1 deadline for digital broadcasting. But in many ways, public broadcasters are at the fore of the digital revolution.

They're among the nation's innovators and leaders in HDTV, datacasting, multicasting, distribution and automation. Armed with a mandate to serve the public-instead of just stockholders-they've turned a struggle for survival of the digital transition into opportunities to re-connect with their communities and break technological trails.

Association of Public Television Stations (APTS) President and CEO John Lawson said 194 public broadcasters (about 54 percent) are asking the FCC for waivers to the May 1 deadline. But Lawson said these are mostly "just-in-case" measures. Many delays will be the result of late equipment and late tower construction, much of it caused by the tough winter.

"We think that by the end of 2003, the number of public station on the air [with digital signals] could be over 300," he said.

Some stations are held back by adminstrative delays or financial problems. In an FCC filing, APTS cited foremost "a critical lack of funding" in its plea for flexibility in granting waivers to the deadline.


Some of those that are on the air are setting examples for their commercial colleagues to follow. WETA, the PBS affiliate for Washington, D.C., for example, beat out commercial broadcasters to grab the local DTV station award from CEA at this year's HDTV Summit.

WETA provides HDTV four hours a day and multicasts four channels the rest of the day; it's been digital so long (since 1998) that it's outgrown some of its earlier equipment.

Now, it continues incremental upgrades, with more server space and new asset management tools.

"One of the things about being a pioneer is that you don't always have the latest and greatest at the later moments in time," said Ed Kennedy, director of technology and engineering at WETA. "Here we are, four years of being on the air officially [plus a couple of years before that doing testing] and our equipment is showing its age. So we're probably one of the first to be forced into a replacement cycle while other folks who are later adopters have the latest greatest and are able to do things [with a little more agility]."

For example, when broadcasting HD, WETA also sends out two "barker" channels to the otherwise unused multicast channels, directing viewers to the channels currently on air. The older encoder can't split the signal into slices smaller than 1 Mbps; Kennedy would like to find a way to reduce that, buying him some robustness on the HDTV signal.

WETA has found other ways to push the limits. "We're probably stressing the Harris automation [system] in ways that none of us thought we ever might," Kennedy said. "Between Harris and us we've discovered new problems and also new solutions. Remarkably, it works very well."


Public broadcasters continue to explore datacasting, which offers new uses of the digital bitstream and appeal to state legislators, the federal government and other sponsors.

Just before NAB2003, New Jersey's NJN completed a test broadcast of emergency messages to public safety agencies near a nuclear power plant. Elsewhere, broadcasters are experimenting with applications such as blasting information to schools and public health agencies.

Whatever the application, public broadcasters have found a technology that can help differentiate the stations from their commercial counterparts and also return to their public-service roots, away from the ivory tower that some see defining public broadcasting.

Digital datacasting has not yet found widespread profitability. But in the analog world, PBS National Datacast remains a leader in datacasting over the vertical blanking interval (VBI) of the NSTC signal. The company, a for-profit venture indirectly owned by PBS, has been doing it for 20 years.

The data from the company's customers piggyback on the PBS satellite transmissions from Alexandria, Va., are picked up and retransmitted by affiliates and received by end users, typically at their PCs. Some of the revenue goes to the affiliates.

"Right now, our customers feel that there is a lot of value remaining in the analog spectrum and that these transmitters really are not going away anytime soon," said PBS National Datacast President Jacqueline Weiss. "So that continues to be our main focus."

Looking ahead, the company is experimenting with Kent, Wash.-based Dotcast Inc. on using the signal at a bit-rate of a few Mbps-far above the dozen or 15 Kbps it can squeeze onto the analog signal. The so-called dNTSC technology is already being tested by a few stations and by ABC, with more deployments planned this spring.

"We're always excited to be working with stations helping them figure out opportunities for themselves on the local, regional as well as national level and we try to do that," said Weiss.

Like their commercial counterparts, public broadcasters continue to pursue their regulatory agenda, namely mandatory cable carriage of both analog and digital channels during the transition and of the multicast channels thereafter.

Public broadcasters have struck system-wide deals with Time Warner Cable and Insight Communications for carriage, and Comcast carried WETA's HD offerings in the Washington market. But those agreements cover only a small fraction of the U.S., Lawson said.

APTS had pitched the FCC a new carriage plan, calling for cable operators to carry digital and analog signals only up to 28 percent of their capacity; cable operators have dismissed the proposal as a rehash of earlier plans and a waste of their carriage capacity.

"Cable carriage is the last remaining piece of the puzzle," said Lawson.