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Proposed FCC Rules Give Fixed and Mobile Services Co-primary Status in all TV Bands

At Tuesday's Open Commission meeting, the FCC adopted its “Innovation in the Broadcast Television Bands: Allocations, Channel Sharing and Improvements to VHF” NPRM (FCC 10-196). While the notice discussed channel sharing in great detail, it didn't discuss spectrum repacking or answer any of the four items I was looking for in the FCC's spectrum plan.

Stations sharing a channel would have the same restrictions, rights and responsibilities for their broadcasts as if each station had its own channel. This includes responsibility for children's programming and carriage rights on cable and satellite. LPTV and Class A stations would also be able to share a channel.

There is a statement in the NPRM that is a little strange: “In allowing stations to share channels, we note that in some instances changes in the operation of television stations could raise the possibility of interference to radioastronomy operations on channel 37 or to services operating on frequencies immediately above channel 51. It is our intent that any channel or other facilities changes that might be requested as part of sharing agreements not result in increased interference to radioastronomy operations on channel 37 or to operations of other services above channel 51.” (Page 6, Paragraph 15).

At the present time, stations operating on channels 36, 38 and 51 have the same emission mask and ERP limits as UHF stations on other channels. To be in compliance with the ATSC standard, stations have to transmit 19.39 Mbps whether they are carrying one program or 10. Sharing a channel would not have any impact on the interference to channel 37 or channel 51, so does this indicate the FCC may propose tighter restrictions on ERP and out-of-channel emissions on stations that share channels 36, 38 and 51 than stations the operate on these channels now? That's the only logical conclusion as I can't believe the authors of this section thought the emissions from a channel shared by two stations using one 19.39 Mbps stream would be any different from the same channel used by one station. On a more positive note, does this emphasis on these channels indicate the FCC may be considering something less than eliminating broadcasting from a contiguous block of spectrum, say the 120 MHz from channel 31 to channel 51? This could potentially allow use of some broadcast spectrum for wireless broadband with waiting the year it would take to install the new broadcast antennas, transmitters, RF systems and perhaps towers necessary to move TV stations off their current channels.

One indication the FCC is keeping their options open is that the proposed change to Section 2.106 “Table of Frequency Allocations” adds fixed and mobile services to all five TV bands – 54-72 MHz, 76-88 MHz, 174-216 MHz, 470-608 MHz, and 614-698 MHz.

While the NPRM doesn't specifically say stations will have to move to VHF channels, a significant part of the NPRM is devoted to the topic of making VHF spectrum more desirable. FCC rules would be modified to allow increased power for VHF stations provided they protect other stations from interference or negotiate an interference agreement. Specifically, the FCC would increase the nominal maximum allowed ERP for low-VHF stations in Zone 1 to 40 kW and high-VHF stations in Zone 1 to 120 kW, for a height above average terrain (HAAT) of 305 meters. As is the case now, maximum allowed ERP is reduced at HAAT above 305 meters. The FCC encouraged VHF stations to use more power in the vertical polarization (elliptical or circular polarization).

The other proposal to make VHF more desirable is to extend all channel receiver rules to include indoor antennas by requiring all indoor antennas meet the ANSI/CEA-2032-A “Indoor TV Receiving Antenna Performance Standard” as measured using the procedures in ANSI/CEA-744-B. The FCC did not see any practical way to reduce the noise from electrical and electronic equipment at VHF frequencies, so it isn't clear that simply making indoor antennas more efficient at VHF will solve indoor VHF reception problems.

Commissioner Robert McDowell recognized this, saying, “I also will review with great interest the submissions we receive on the topic of potential technical improvements for digital broadcasting on VHF channels. As one of the two remaining veteran commissioners of the digital television transition, I have not forgotten the difficult and unanticipated challenges that we and broadcasters on those channels faced at the time of the analog shut-off. Both industry and FCC engineers scrambled throughout the spring and summer of 2009 to try to overcome interference and other reception problems associated with VHF channels. What had been prime real estate in the days of analog broadcasting sometimes became a rough neighborhood in the new digital era. Before the Commission takes action that might lead to more broadcasters moving back into those channels, I will want to fully understand the ramifications of such a decision.”

Commissioner Mignon Clyburn expressed concern about the impact on broadcasters, saying, “But I cannot stress enough that we must pay careful attention to those who are most vulnerable to the loss of broadcast television. We learned during the DTV transition that a large number of Americans, such as seniors and the very poor continue to rely on broadcast TV to stay informed. Those communities that heavily depend on broadcast programming should not have to sacrifice those benefits in order for our Nation to attain wireless broadband services.”

Commissioner Meredith Baker had some of the most interesting and innovative comments on the future of broadcast TV, saying, “In the future, there needs to be a fulsome discussion on additional innovative proposals to address sharing of broadband and broadcast in the TV bands, including the possibility of a broadcast transition from MPEG-2 to MPEG-4, the adoption of a more cellularized broadcast system, or a transition from ATSC to OFDM technologies. These are by no means the only potential approaches and may have their own weaknesses and strengths. And in all fairness, we also should ask additional questions about the future applicability of public interest obligations on broadcast licensees. If the TV bands are to shift towards a more flexible spectrum model, it is only right to ask whether those use restrictions should also be revisited.”

The proposed rules are in Appendix A of the NPRM. Comments on the rules will be due 45 days after the NPRM is published in the Federal Register. There is an additional 30 days allowed for reply comments.

Doug Lung is one of America's foremost authorities on broadcast RF technology. He has been with NBC since 1985 and is currently vice president of broadcast technology for NBC/Telemundo stations.