Last November, the FCC approved the use of distributed transmission systems (DTx) by TV broadcasters to cover the area once covered by analog TV signals. Of course, this was a little late in the day for broadcasters facing an imminent deadline for analog TV shutoff, but, as the ATSC finalizes the new ATSC (M/H) standard, it's good timing for those broadcasters considering their mobile TV strategy.
Because mobile TV presents the same problem that DTx is designed to solve (ensuring coverage), the timing of the FCC's blessing is ideal for local broadcasters
"In the past, for broadcasters who have chosen to use it, it has been on a temporary or experimental basis," said Jack Wilson, marketing and business development director at Axcera, a company that has been manufacturing TV transmission equipment for more than a quarter of a century and deployed the first DTx system in 2005.
DTx is now recognized as a permissible solution, Wilson said, "a regulatory paving stone to U.S. broadcasters offering viable mobile TV service. U.S. broadcasters are using ATSC for terrestrial, and [the ATSC] handheld should be a standard in 2009. Those two things will dovetail together.”
"What do people have to watch 'right now'?" he said. "A lot of it is local content. For domestic broadcasters, it makes them suddenly relevant again. This is a whole other opportunity to capitalize on an ad-based service."
DTx is "absolutely essential" to deploying a commercial mobile TV network, according to Wilson. "When you have terrestrial broadcast to a fixed TV, you have an antenna outside. It's bigger so you have higher gain. But when you're trying to receive a signal on mobile devices, they're not outside and they have smaller antennas,” he said.
"To get in-building coverage, you need several lower-power transmission sites deployed in a single-frequency network," Wilson said. "Otherwise, if they're not synchronized, then the receiver picks them up as noise and doesn't receive anything. The latest generation of receivers picks up multiple paths of the signal from different sources and adds them together to make a stronger signal."
Anticipating that broadcasters will be gearing up for when the ATSC releases the new mobile standard, Axcera recently launched products specifically designed for mobile TV.
The new products include what appears to be the market's first ATSC M/H compatible exciter. Built on the company's established DTV exciter platform, the new technology can also retrofit existing ATSC exciters — regardless of manufacturer — in effect making any transmitter DTS and ATSC M/H compatible.
But Wilson cautions broadcasters not to take a piecemeal approach to DTx. "DTx is a whole solution — not just a box. It's a whole network." He advises broadcasters to look for partners with a comprehensive product line as well integration and coverage planning services. "Axcera has a complete portfolio of DTx solutions," he said. "I don't know anybody else who does. And we have a successful track record."
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