A critical part of the commission's push to find more spectrum for wireless broadband is to improve the quality of TV signals in the VHF band that were weakened in the digital transition. Among its suggestions are boosting transmission power and setting reception standards for home antennas. Broadcasters are skeptical of the plan's viability and are worried that they may be forced to move from the UHF band to VHF, requiring expensive equipment while potentially lessening their coverage and alienating their viewers.
FCC Plan Makes VHF A Very High Priority
As part of its plan to shift 120 MHz of spectrum from TV broadcasting to wireless broadband, the FCC wants to pack TV stations more tightly together in the remaining 180 MHz of spectrum to free up some for auction.
To do that most efficiently, it must make the VHF portion of that remaining spectrum (chs. 2-13) more hospitable to broadcasting.
That process got underway on Tuesday, when, as part of a larger rulemaking on TV spectrum reallocation, it proposed increasing the power of VHF stations and imposing minimum performance standards on VHF receive antennas. It also called for other ideas for making VHF work better.
The initiative is badly needed. After the final transition from analog to digital in June 2009, the VHF band, particularly the lower end (chs. 2-6), was exposed as a digital weakling.
As the FCC pointed out in its rulemaking, viewers who happily watched analog signals on VHF channels suddenly couldn’t get a picture when the stations switched to digital signals.
“Most of these reports involved situations where the consumer was using an indoor antenna,” the rulemaking says. “In addition, earlier in the transition process it was recognized that use of the low-VHF channels 2-6 for digital service could be particularly difficult because of the generally higher levels of background noise on those channels.”
Just before casting his vote in favor of the rulemaking, FCC Commissioner Michael Copps said what many others believe: improving the VHF service would not be easy. “We looked everywhere we could during the DTV transition, and real remedies were few and far between. Let’s hope the months ahead lead us to some genuine innovation.”
In the rulemaking, the FCC floats two ideas for reinvigorating VHF broadcasting.
First, it proposes to raise the maximum transmitted power (effective radiated power or ERP) of VHF stations in its heavily populated Zone 1 (the Northeast and Upper Midwest). Stations in the low-V band could up their power to 40 kW, while those operating in the high-V band could go to 120 kW. If the broadcast antennas are higher than 305 meters above average terrain, the power limits would be somewhat lower.
The greater power “would help to compensate for some of the higher noise levels that tend to be present where consumers use indoor antennas,” the rulemaking says.
Second, the FCC proposes a standard for receive antenna performance, namely the ANSI/CEA-2032-A standard. It demands that antennas produce gain of at least -12 dBd on low-V channels and -8 dBd on high-V channels.
“While we have not regulated these products previously, we believe that we have authority to set standards to ensure that the performance of indoor antennas is adequate … under the All Channel Receiver Act,” the rulemaking says. The act first required UHF tuners and, later, digital tuners in all TV sets sold in the U.S.
The FCC also suggests that VHF stations looking to improve service add a vertically polarized element to their broadcast antenna if they don’t already have one.
“Stations … could achieve an increase in signal levels at indoor locations of perhaps 3 dB by using circular polarization,” the rulemaking says. “This step could also be combined with an increase in … horizontal ERP under the proposal to allow higher VHF maximum power levels.”
Two broadcast consulting engineers who earlier this year participated in the FCC’s Broadcast Engineering Forum were underwhelmed by the FCC proposals. The forum was aimed at addressing such problems as VHF reception.
Charles Cooper, at duTreil, Lundin & Rackley, said the four-times power increased proposed by the FCC can’t hurt, but that it will have limited application.
That’s because power, particularly in the Northeast, is constrained more by the need not to interfere with other stations than by the nominal power limits, he said.
“The stations would have to seek interference agreements with other stations, and most likely, these agreements could involve daisy chains involving multiple stations and perhaps those other stations having an issue with even other stations,” he said.
Cooper cited New York City as an example. The high-V stations there — WABC, WNET and WPIX — are now operating with ERPs of 12 kW or less, he said. In theory, under the FCC proposal, they could boost power to 50 kW, but, in fact, they couldn’t do that unless they negotiated multiple interference deals with stations in the surrounding markets.
Ross Heide, a consulting engineer at Cohen, Dippell & Everist, agreed with Cooper, noting that the rulemaking doesn’t “do anything to relax the interference constraints.”
Many of the troubled VHF stations have already gone to the FCC and gotten power boosts on an ad hoc basis, Heide said. “I think that pretty much everybody that was capable of doing that did so.”
But there may others who may still be able to take advantage of increased power “if they don’t have to go through a waiver or the experimental process,” Heide added.
Heide did not see anything new in the FCC’s suggestion that stations add vertical polarization. More stations would do it if they could justify the expense, he said. “Adding vertical polarization to your existing antenna is seldom a viable way to get to go. It can mean buying a whole new antenna.”
What might drive VHF broadcaster to circular polarization is mobile DTV, he said. If that service takes off, stations will have a real incentive to improve coverage. “And that will also help with indoor reception.”
Richard Schneider, of Ellisville, Mo.-based Antennas Direct, an online retailer of TV antennas, is skeptical about whether anything can be done to antennas to improve VHF service, particularly on the low-V channels.
The low-V band is plagued by too much “RF haze” from motors and other electrical devices, he said. “There is a lot of stuff that didn’t even exist 10 years ago — battery chargers, compact fluorescents, transformers.”
The high-V band is better because it is not as susceptible to the interfering noise, he said. But UHF is where everybody wants to be. “The UHF band is the cleanest,” he said. “We get the most consistent, reliable reception of those frequencies.”
Cooper also didn’t see an antenna with improved gain as a panacea. In boosting signals, antennas don’t discriminate between the good ones (TV) and bad ones (electrical noise), he said.
“As we found out after the DTV conversion, there is substantial electrical noise caused by unintentional radiators (such as DVD players, vacuum cleaners, leaf blowers, etc.) that cause reception failures,” he said.
Cooper noted that the FCC decided not to do anything to try to curtail the environmental interference to VHF.
Since the digital transition, most stations are now broadcasting in the UHF band. Some of them are worried that in trying to improve the VHF band, the FCC is signaling that it intends to force some UHF stations back to the VHF band.
Among them is Dan Ullmer, chief engineer at WECT Wilmington, N.C., which made the leap from VHF to UHF in September 2008 when it because the first station in the nation to switch to all-digital service.
“We have really good coverage along the coast now,” he said. “Going to VHF would be going backwards for us. We have built out all-new UHF facilities, UHF antennas. All that would have to be changed out. We’d have to enter another major transition in the market, which would likely disenfranchise our viewers. They’ve already been through a major transition here.”