As the over the-air-broadcast industry seeks to establish its place in the future of television distribution, it is looking past high-powered, single-stick transmission to a distributed model of multiple lower-power systems that
ring a market, thereby ensuring better signal coverage for mobile video and other next-generation viewing applications.
However, such systems, also known as single-frequency networks (SFNs), are most successful when using a modulation scheme (OFDM) that is only approved by the FCC for specific applications. The mandated U.S. standard is one developed by the Advanced Television Systems Committee (VSB).
There are a few SFNs now deployed around the country in geographically diverse markets, providing extended reach from a single transmit site. Idaho Public Television uses a distributed transmission system or SFN. Basical
ly, a full-power origination site feeds a series of lower-power transmitters throughout the state.
Sinclair Broadcast Group, which has promoted OFDM for the use in the U.S. for at least a decade, was recently granted a six-month, temporary license to broadcast using the DVB-T2 European standard at WNUV-DT, the CW affiliate in Baltimore (where Sinclair is headquartered). Many will be watching the results of this test in comparison to what can be accomplished with the ATSC spec.
“I think it’s fairly obvious that the next digital broadcast system that gets adopted will be an OFDM- or multicarrier-based system,” said Jay Adrick, a long-time ATSC committee member who recently retired as vice president of Broadcast Technology for Harris and now serves as a technology advisor to the company’s Transmission business unit.
[Adrick has been named the recipient of the 2013 NAB Television Engineering Achievement Award, and will be honored at the 2013 NAB Show Technology Luncheon, Wednesday, April 10, in Las Vegas.]
Adrick was a key figure in the development of the current A/153 ATSC Mobile DTV system.
“We need this in order to accommodate mobility and because of the fact that broadcasters have to employ a more cellular approach in the future,” he said.
That cellular approach is part of the work being done within the ATSC on what will eventually be called “ATSC 3.0,” which is expected to be adopted by the U.S. government and the FCC in 2016.
“Through experiments like what Sinclair is doing, we're going to learn something,” Adrick said. “That’s good for the industry.”