RF Engineers Eye The Future Of TV Spectrum

Stations that need to change out their transmission facilities due to the spectrum “repack” that will occur as part of FCC’s incentive auction of broadcast spectrum would do well to look ahead to their ATSC 3.0 future, said top RF engineers at TVNewsCheck’s TV2020 ATSC conference during the NAB Show New York on Thursday.

Speaking at the “The RF Roadmap: 3.0, SFNs and the Repack” panel, RF consultant and industry veteran Jay Adrick reminded the audience of a “small distraction going on in the industry” — the TV spectrum auction that will eventually result in the UHF spectrum band being realigned and repacked. 

Of course, the auction process whereby stations have put their spectrum up for bidding by the FCC which will then subsequently sell it to wireless companies, has gotten off to a slow start. A high initial asking price from broadcasters coupled with weak demand from telcos has forced the FCC to lower its target of “cleared” spectrum from 126 MHz to 114 MHz, then to 108 MHz. 

Adrick noted that the auction is now in its third round and that he was not real confident that the third round will result in a successful conclusion, where the cost of the cleared spectrum is offset by the wireless companies’ payment. He said that such a closing might not happen until the fifth or sixth round.

“It’s the old story of the wheel goes round and round, and where it stops nobody knows,” he said. “But 84 MHz might be where it stops.”

At an 84 MHz clearance, between 1,020 and 1,164 stations would need to repack, according to research from DTC and the FCC.

Besides the uncertainty over when the auction will actually close, there are other “open issues” in the industry, said Adrick, including whether broadcasters can actually repack in 39 months, whether the $1.75 billion from the government will cover the cost and whether there will be enough transmitter and tower crews to do all the work. 

That said, broadcasters should start looking ahead to whether they will need a higher power transmitter to make up for a lower-gain antenna on their new channel, as well as whether they will need a higher-power transmitter to support OFDM operation under ATSC 3.0 in the future.

“You have to make sure you’re purchasing the right antenna to serve the future marketplace with ATSC 3.0, then a transmitter with the power and an upgrade path to 3.0,” Adrick said.

He noted that stations setting up single-frequency network (SFN) sites would be able to contain costs by sharing a lot of infrastructure including the transmitter building, tower, transmission line and antenna at each site. Stations would have to buy their own transmitter and mask filter and provide their own studio-to-transmitter link.

Cindy Hutter Cavell, senior engineer with RF engineering firm Cavell, Mertz & Associates, said that stations with “squirrelly antenna patterns” from the last repack should take another look at them, because they might not need them after the next channel change. She then walked through some of the considerations stations have to weigh if they want to eventually use a single-frequency network (SFN) architecture to boost coverage in the 3.0 world, and gave an example of how coverage would improve in the Washington, D.C., market when a single-stick station added from one to four repeaters.

“It’s all about signal density,” said Hutter Cavell. “You have to have good signal strength to reach those portable and mobile devices. I don’t care if it’s ATSC 1.0, 3.0 or 9.5, you need signal strength.”

Another fan of SFN architectures is Dave Siegler, VP of technical operations for Cox Media Group, who gave a general overview of 3.0’s capabilities and said broadcasters have to adopt the proposed standard to keep technological pace with their competitors and adapt to changing viewing habits such as increased mobile consumption.

“ATSC 3.0 is the glue to bring together broadcast and the Internet,” said Siegler. “These other platforms are out there eating our lunch, and we need to get there.”

Cox’s goal with ATSC 3.0 is not to launch with 15 new services but instead to focus on three or four and do them really well, said Siegler. Possibilities that seem to appeal to younger consumers would include 4K video, enhanced audio options and targeted advertising. But rolling out 3.0 successfully will likely require an unprecedented level of cooperation among broadcasters as they aggregate transmission resources to create SFNs, and perhaps share bits to launch new data businesses.

“This is going to be new to us,” said Siegler. “We’re going to have to forge relationships, and work together, and we don’t generally do that today.”

That said, Siegler conceded that the spectrum repack mandated by the FCC will already require significant cooperation among broadcasters to be done successfully, outside of a potential optional move to 3.0.

“There’s a lot [of cooperation] needed in the repack, so maybe the repack is the practice,” said Siegler.

Jason Effinger, chief digital and technology officer for Gray Television, said the robust reception of 3.0 combined with the reach of Gray’s 90-plus major network affiliates would give the group the opportunity to “serve corridors” across the U.S. with mobile and interactive services. 

Given the improvements in compression technology, said Effinger, in some markets all four or five big-network affiliates could do high dynamic range (HDR) HD programming and “still have plenty of real estate to bring to the table” in terms of available bandwidth.

One of the big opportunities in ATSC 3.0 that Gray sees is the ability to use data analysis to deliver targeted advertising on multiple screens. 

“It’s about predictive behavior,” said Effinger. “For example, we know that when it rains in ZIP codes around colleges and universities, pizza and beer sales skyrocket. The predicted delivery of advertising content in screen-specific ways is a big opportunity when you tie it into news and sports.”

See all of TVNewsCheck’s TV2020 coverage here.