Prompted by auction sales, moves to low VHF bring both challenges and advantages

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Big rooftop antennas could sprout again to receive TV stations transitioning to low-VHF channels.

Several public television licensees have opted to take a technological step backward in exchange for cash from the FCC spectrum auction that will help finance their stations’ futures.

Among the 28 licensees in the auction who operate public TV stations, eight chose to shift channels from the more commonly used UHF spectrum to VHF. Seven chose low-VHF — Channel 6 or below, which decades ago aired the earliest TV signals on tube transmitters.

In addition to grabbing big payouts, such as $161.7 million for WGBH in Boston and $94.4 million for Rhode Island PBS, the stations going to low-V will also save money on utilities for equipment that costs far less to power.

However, that VHF transmission equipment — until now considered legacy broadcasting technology — can be difficult to find. To fill the need, equipment manufacturer GatesAir this month debuted a transmitter that covers the entire VHF spectrum, including low-V.

Over-the-air viewers will need different — and larger — antennas.

Viewers tuning in to the low-V stations will also discover that, unlike UHF, the channels are prone to interference from anything run by electricity: microwave ovens, computers, even fluorescent lights.

And although operating on low-V doesn’t stop stations from upgrading to the new ATSC 3.0 protocol, it does preclude transmitting content to mobile devices due to the larger receiving antennas necessary.

“There’s a whole litany of physical challenges” for mobile, said Bill Hayes, director of engineering at Iowa Public Television. Those issues “are less about transmitting and much more about receiving.”

Despite the challenges, Rich Redmond, chief product officer at GatesAir, was not surprised that moving to VHF was a viable option for public stations, several of which are his clients.

“They could get almost as much money for moving to low-band as for totally selling their spectrum,” Redmond said. “Plus, there’s significantly lower operations costs. So it was a good opportunity to still meet their public-service mandate and serve their community as well as change up their game financially.”

Auction proceeds, plus savings

Before the FCC auction began last May, the majority of public TV stations — 258 — were broadcasting on ultra–high-frequency (UHF) channels between 14 and 51.

A smaller number of public stations, 105, used very high frequency (VHF) spectrum. That spectrum is divided into low-V, channels 2 to 6, and high-V, 7 to 13. Prior to the auction, all but five public stations were high-V.

“When we were analog broadcasters, the technology was more stable and had better market penetration in the lower channels,” said David Piccerelli, president of Rhode Island PBS. “Now with digital, it’s the opposite — higher channels are much more stable.”

Wireless providers bidding in the auction wanted to acquire UHF spectrum to reach mobile devices. So broadcasters earned the biggest payouts by either selling off that bandwidth or moving from UHF to VHF spectrum.

A portion of the payouts will go to equipment costs. “Everything from the encoders to the broadcast antenna will be changed,” said WGBH CTO Stacey Decker. “Where possible we will repurpose anything we can.” Another of the station’s channels, WGBY in Springfield, Mass., is moving to high-V Channel 13. The broadcaster will continue to operate UHF channel WGBX, which covers nearly the same area as WGBH’s current UHF signal, according to station spokesperson Jeanne Hopkins.

VHF equipment is cheaper than UHF, said Bob Gehman Jr. of Kessler and Gehman Associates, a telecom engineering firm consulting with some 50 public broadcasters.  “low-V is even less; transmitter powers are lower,” Gehman said. “If you want to go for broke and maximize your power, you can spend money on an antenna. But even then you’re looking at $100,000 for a low-V antenna versus $300,000 for UHF.”

Piccerelli estimated that Rhode Island PBS will spend $2 million on equipment and engineering costs to move from Channel 21 to Channel 2. At WQED in Pittsburgh, which earned $9.9 million in the auction, Engineering Director Paul Byers said he’s estimating $1 million for equipment including a transmitter, antenna replacement and new encoders.

Once station transitions are complete, savings kick in. “Channel 4 uses a lot less power to cover the same area than, say, Channel 40,” Redmond said. “If you needed to run a 40-kilowatt transmitter on Channel 37, and went to Channel 3 or 4, you might be running a 5-kilowatt transmitter. Much lower power. So then you can reinvest those savings as well.”

For that reason, WQED requested to return to its original high-V Channel 13 after the 2009 transition to digital placed it on Channel 38, Byers said. “Power bills on the high-V transmitter were exponentially less,” he said. “It cost $10,000 a month to run Channel 38 and about $1,000 a month for high-V.”

But broadcasters have tended to avoid low-V due to manmade noise interference. Anything electrical radiates noise, Hayes said. “In the old days on analog low-V, you’d see on the TV screen sparkling or black noise spots when someone drove by with a bad spark-plug wire. You could see that flashing on the TV. That’s just physics.”

“And now,” Hayes added, “there are a lot more noise sources.”

Gehman said stations need a higher-power signal to cover the noise. “You want to maximize your facilities to get more power,” he said. “Not a larger coverage area, but a better signal within it.”

“Bump up the power,” Gehman said. “It’s just a little more money for the transmitter. Even if you go from 1 kilowatt to 4 kilowatts, it’s a small cost increase.” The increase should cover annoying electrical interference from things like car engines, appliances and electrical power lines.

Byers said WQED will most likely request an increase in power. The FCC is opening a special filing window for stations to apply for a power hike.

Another challenge for stations is that low-V antennas are much larger than those for UHF. “So engineers will be figuring out, is there space on our tower? How can we move things around?” Redmond said.

Consumers need bigger antennas as well. “Rabbit ears and loop antennas that work fine inside for UHF won’t work well for low-V,” Redmond said. “If you happen to have a rooftop antenna leftover from the analog days, those will probably work pretty good.”

The relatively small sizes of stations’ over-the-air audiences also figured into their discussions of moving to low-V. In Rhode Island PBS’s market of Providence, R.I. and New Bedford, Mass., 94 percent of the audience receives the station by cable or satellite. “That was a big part of the decision,” Piccerelli said.

And not all over-the-air households will experience impaired reception, Piccerelli said. “We’ll deal with it on a case-by-case basis,” he said.

Pittsburgh’s WQED also has a “very high cable penetration rate, more than 90 percent,” Byers said. “But that doesn’t mean we don’t care about our over-the-air audience.”

Those viewers might get a bit of help. During WQED’s auction planning discussions, “we talked specifically about the need for antennas and how we might facilitate that,” said President Deborah Acklin. Details are still being considered, she said.

Clarification: This article has been updated to clarify that WGBH’s UHF coverage area will remain largely unaffected with the continued broadcast of UHF signal WGBX. 

  • Brad Deltan

    It’s not just electrical noise. The 8VSB transmission system that the current ATSC1.0 schema uses is incredibly intolerant of multipath interference. This is why a lot of over-the-air TV viewers near wind turbines have suddenly discovered they can’t get TV reception worth squat anymore.

    https://en.wikipedia.org/wiki/Multipath_interference

    The effect is markedly more problematic in VHF than it is in UHF, and the lower you go (lo-VHF, channels 2-6) the worse it gets.

    Fortunately ATSC3.0 uses a CODFM transmission system, which is not dissimilar to HD Radio and is far, far more multipath resistant. In fact, in some cases it performs BETTER in multipath because it’s ultimately getting more signal into the receiver. But we’re not at ATSC3.0 yet and won’t be for a few years at least.

  • wt_hayes

    While I agree that bumping up the power would increase signal density and improve reception, I would still be concerned about over the air reception in the presence of man made noise sources. If we assume an outdoor antenna on the roof and that the television receiver is properly shielded then the additional 6 dB of signal will help. However, many of the man made noise sources are located in close proximity to the television. Most televisions are not that well shielded. It is also unlikely that the receive antenna is mounted outside and certainly not at the 10 meter elevation above ground level that is used for predicting coverage.

    I am also not sure everyone will be able to bump up their power to as great a degree. I ran a quick study of KVCR using their existing site and then replicating their existing UHF coverage with a low band VHF service and then modeled a 4 times power increase which extends their principal community contour an additional 35 or so kilometers which I know isn’t the target but it is a result of the power increase. I suppose the position could be made to the FCC that while the calculated contour is significantly extended the actual coverage area is not due to terrain in this particular case. However, I expect this change would have to be approved by the Mexican government due the border proximity.

    I’m not throwing stones here about any station’s decision to move to low-VHF. As a business decision it may be a good one based on the plan and vision of the station involved. It will definitely be a lot less expensive to power the transmitter and if implemented properly it will protect the station’s must carry rights and carry one-carry all rights with MVPD’s. I just think we need to be realistic about the over the air reception of low band VHF. In the above example of KVCR, the reason there are low band VHF channels available in that area is that at the end of analog, KCBS, KNBC, and KTLA in Los Angeles all opted to stay on their UHF DTV assignments rather than go back to their low band VHF assignments. I have to believe that reception, especially indoor reception was part of their reasoning for opting to pay the higher power bills.

  • Terry Douds

    I believe it’s a combination of all of these points – the opportunity to get a windfall in the move to low-V, as well as the lower electricity costs AND the upcoming move to ATSC 3.0. Admittedly 8-VSB has not fared well in low-V; many stations who elected to return to their original channels after analog cutoff were not happy with that decision. Upping the power level of the transmitter can definitely help, but as Bill pointed out, it comes with extended range issues that can be a sticking point. In our situation at WOUC, we have to protect Altoona, PA (209 miles to our East), while we’re wide open North/West/South. We are anticipating applying for a power bump to help with the mobile reception issue (and hopefully overcome any noise issues), but as digital vs. analog, the noise affects the situation differently. The resultant audio “whirr” & whine from sparkplug issues affects the digital signal differently, and if the signal level provides enough “oomf” to allow error correction to still help out, the effects will be minimal; bulb noise from CFL’s is diminishing as LEDs are replacing them; and in our geographic scenario, we primarily broadcast into the “valley” formed by I-77 going N-S across eastern Ohio. We are of the opinion that our coverage area will not be significantly affected by the change, and we’re counting on our consultants and Antenna design personnel to help us affirm that belief. Once we can transition to ATSC 3.0 however, I feel the effects will be minimized to a greater extent, and the benefits of the new system will help the viewers to see the station in this new manner. Other issues abound of course, such as getting the wireless folks (who just paid for the Auction) to begin implementing TV reception in their smartphones! This would help everyone immensely in my opinion, as we would gain viewership from those on the go who currently utilize their data plans to see streaming video from program providers – the Wireless folks want us to use data, but then they’re all going to “unlimited” data plans anyway – why not alleviate some of the overhead and let the viewers watch the OTA signals? Just my 2 cents…