So Soon? Next-Gen Broadcast TV In Works

It’s been less than two years since TV broadcasting switched off the last analog transmitter and went all digital. But the actual digital broadcast standard — ATSC DTV — is actually a lot older than that.

In fact, it’s 15 years old if you start counting from when the FCC adopted it, 16 if you start counting from when the consortium of technology companies — the so-called Grand Alliance — put the system together and a few years older still if you go back to when the various components of the system were actually invented.

That’s a long, long time ago given the lighting speed with which electronic media evolves these days. And that’s why far-sighted broadcasters and technologists, under the aegis of the Advanced Television Systems Committee, have begun work on the next-generation TV broadcasting standard.

Even as some viewers still fiddle with DTV converter boxes, next-gen proponents say a new system is needed within the next several years so that TV stations can broadcast more programming, more reliably to more places and explore new business opportunities.

“At some point, broadcasting, like everything else, has to move to the next stage of technology,” says Mark Richer, president of the ATSC, whose board is expected to take the next step toward a next-gen standard when it meets in Washington in two weeks.

Jim Kutzner, chief engineer, Public Broadcasting Service, and chairman of ATSC’s next-gen planning committee, agrees that it’s time. “If you don’t start now, many years down the road you’ll be in the same place.”

Kutzner also sees the effort as a hedge against the FCC’s proposal to take big swatches of spectrum from broadcasters and make it available to wireless broadband providers. The FCC is pushing the plan, despite stiffening opposition of broadcasters.

“If the broadcasters are consolidated down into a smaller amount of spectrum, then we will have far less spectrum to transition from where we are today to where we want to be in the future,” he says.

To be determined is the urgency. While some proponents would like to put it on the fast track and bring the standard home within five years, others are looking at five to 10 years.

Whenever it comes, next-gen TV will not be backward compatible with DTV as color TV was with the original black-and-white TV in the 1950s. This will mean another traumatic transition similar to one leading up to the final June 2009 switch from analog to digital.

“Sometimes to build a better mousetrap, you have to start over,” said Richer. “That’s what we are going to do.”

The standards-setting work is still in its early stages, but already there seems to be a consensus that the third iteration of broadcasting — the first was 1941-vintage NTSC — should be far more efficient in its use of spectrum than today’s DTV system. Proponents talk of achieving it in a couple of different ways.

First, the standard would feature improved compression of video, audio and other content. “Broadcasters could use far fewer bits to deliver the same program at the same quality or deliver higher quality using the same bits we use today,” PBS’s Kutzner says.

And, second, it would allow stations to pump more bits through any given bandwidth. How many more Kutzner couldn’t say, but certainly, he says, “a substantial improvement” over the 19.4 mbps in 6 MHz now possible with DTV. “There are new techniques that approach Shannon’s Law, the theoretical limit of the ability to push bits through a channel,” he says.

The standards setters would also look for a marked improvement in the transmitted signal so it could be received on small indoor antennas and on mobile devices.

The current DTV transmission system — VSB — has been criticized for its poor propagation, especially in the VHF band. To receive it reliably, rooftop antennas are needed in most places.

And for mobile service, ATSC had to come up with a supplementary standard that forces stations to use up precious bandwidth to transmit a second signal that is suitable for viewing only on small screens.

“The ATSC is not tasked with figuring out how can we deliver broadcasting to a wider area, but they are thinking about, within the area that stations serve, how can we up the reliability in more diverse receiving configuration like indoor reception,” says Lynn Claudy, SVP, science and technology, National Association of Broadcasters, which is taking an active role in the next-gen push.

One option already under consideration for the standard is a multi-carrier OFDM modulation scheme that was considered, but finally rejected, for DTV in the 1990s, and which is widely used in other parts of the world.

ATSC may be feeling a little competitive heat to get going on a next-gen standard. NHK in Japan is developing a system, Richer says. And in Europe, some broadcasters are already on the air with a second-generation standard called DVB-T2.