Doug Lung /
07.01.2010 02:35 PM
FCC Broadcasters Forum Yields No Magic Spectrum Solution

The FCC Broadcast Engineers Forum held last Friday consisted of some of the most experienced and skilled broadcast engineers in the country, although as each panel gave its report, it became clear that there was no way to eliminate all TV channels above channel 30 without a serious impact on TV broadcasting. For non-technical readers, it is important to note that the channels the FCC is proposing to eliminate are not the channel numbers you see on your TV set or program guide but rather the channels the station is actually transmitting on. For example, in Los Angeles KNBC, virtual channel 4 transmits on channel 36 and KCBS, virtual channel 2 transmits on channel 43. Both would lose the RF channel they use to transmit their signal over the air, although they may be able find a new channel and build a new transmission facility on another channel to continue to provide free over-the-air TV.

"Cellularization" of broadcasting would provide little if any new spectrum and be technically difficult and expensive. Changing stations' channels to more efficiently use the spectrum—"re-packing", even if protected coverage areas are reduced, will yield little extra spectrum. More stations will have to use VHF channels, and beyond some limited relief from power increases, there is no magic solution to making VHF as effective in reaching smaller antennas as UHF. The VHF reception panel suggested the best use for the low-VHF spectrum might be as a "technological innovation" band in areas that would not impact the few remaining low VHF DTV stations. The panel on compression explained that combining two or more stations on one channel will work only if one or both of the stations are willing to make compromises in HD quality, multicast offerings, mobile DTV capability—or all of the above. MPEG-4 promises better compression efficiency, but it could take 13 years to replace all the MPEG-2 TV sets and converter boxes now in use.

One of the interesting things I noticed during the forum question and answer periods at the end of each panel discussion was that there was little if any argument on the purely technical points made by the panel. If there was a point of disagreement, it was that the panels treated the National Broadband Plan recommendations to clear 120 MHz of the broadcast spectrum as if it would result in all broadcasters being forced to share spectrum or reduce coverage. Evan Kwerel, acting FCC Wireless Bureau Chief Economist said this would impact only 4th or 5th tier stations running mostly reruns, some in black and white, and not networks. This implies the reward would either be great enough or the penalty and costs high enough that many TV stations would voluntarily give up their channels.

I'm encouraged by the format the FCC used in the forum. The depth of material assembled by the panels in less than a day is amazing, although perhaps not surprising due to the caliber of panel participants. Julius Knapp did an excellent job as moderator and even managed to end the forum early. This work cannot be ignored as the FCC decides how to achieve its wireless broadband spectrum goals. If they do and focus solely on dollars as the measure of public benefit, the record will show the resulting fiasco and public outrage cannot be blamed on the broadcast engineering community. Unfortunately, viewers tended to blame broadcasters for the loss of analog TV even though that was mandated by Congress and the FCC. Of course most broadcasters were happy to stop maintaining and supporting the equipment to transmit on two channels.

Now that the President has supported taking TV broadcast spectrum for broadband (voluntarily, of course), there is little doubt this will impact all but the smallest stations and perhaps those on low VHF channels. The video and presentations presented in this forum are the best way for TV engineers to get an understanding of the implications of taking away TV channels above 30 so they can explain it to non-technical management. The FCC has made a video of the approximately two and one half hour FCC Broadcast Engineering Forum available at Reboot.FCC.gov/video-archives. Individual panel presentations are available as PowerPoint files on the FCC Broadcast Engineering Forum page.

To encourage you to download the presentations and, if possible view the video, I'll provide some short summaries of each panel's presentation:

Andy Setos from Fox Broadcasting delivered the Advanced Compression Technologies presentation. He showed that demands for broadcast bandwidth are still increasing—licensees are still migrating to HD and at some point won't be able to depend on SD material being available. Forcing stations to share channels will require picking winners and losers. This is the point that Evan Kwerel strongly disagreed with—the losers will pay less. In addition to Andy Setos from Fox, the panel included NBC's Glenn Reitmeier, David Converse from ABC, and Greg Coppa from CBS. These are people that know from practical experience what the limits are on quality and what viewers and advertisers want. Cox, ION, and Capital Broadcasting also had one of their top engineers on the panel, providing more real world experience. See the Agenda and Forum Participants for a complete list.

The Cellularization of Broadcast Architecture and Distributed Antennas Systems panel included Merrill Weiss, who I would call the "father" of distributed transmission for ATSC due to his work on the ATSC standard and his work with the FCC to make it available to broadcasters; and Dennis Wallace, who I think it is safe to say has done the most ATSC fixed, DTS and mobile DTV field measurements of anyone in the country.. Harris Corp., Sinclair, Sprint, CTB Networks, and Motorola had an engineer on the panel. Bob Seidel from CBS was on the panel and delivered its presentation. The presentation shows, step by step, why going to a cellularized broadcast network will provide little or no additional spectrum and will not work to provide stronger signals at the edge of a station's contour because of interference to adjacent markets. The presentation includes some very interesting maps showing the number of channels that can be received in locations around the country. The maps show there are many counties in the U.S. where viewers can receive more than 28 channels over-the-air and some in California and around Chicago, and many throughout the northeast where viewers can now receive more than 37 channels. It will be very difficult to find spectrum below channel 31 for all TV stations, even if some share channels.

The VHF Reception panel included Victor Tawil from the Association for Maximum Service Television (MSTV), Jeff Johnson from Gannett, and a trio of broadcast consulting engineers—Greg Best, Charles Cooper and Ross Heide. Dave Young from Antennas Direct and Will Belt from the Consumer Electronics Association provided expertise on receive antennas while Kerry Cozad from Dielectric covered transmitting antennas. The panel's presentation provided a short lesson on antenna theory, then addressed practical issues. The problems with VHF DTV reception have been widely reported and I won't repeat them here. Refer to the panel's presentation for one of the best summaries I've seen of the issue. The "Final Thoughts" slide sums things up nicely: "Improvement in VHF reception is difficult and limited by the laws of physics; RF environment; practical limitation of transmitting and receiving equipment design."

The last panel to present covered the methodology for repacking. This group had to look at ways of moving all of those stations above channel 30. Panelists included Bill Meintel, who worked with the FCC in writing the software it used to determine coverage, interference and DTV Tables of Allotments, Bruce Franca, an engineer in the FCC's Office of Engineering and Technology before MSTV, and Dr. Byron St. Clair, who most consider the father of translators and LPTV. They were assisted by the top engineers from Univision, PBS. Gray Television Group and Lin Broadcasting. Broadcast engineer Joe Snelson represented the Society of Broadcast Engineers. Mel Frerking from AT&T provided the wireless carriers' perspective.

The Repacking panel looked at the analysis in OBI Technical Paper No. 3 – Options for Broadcast Spectrum and outlined the short-comings and flaws in the analysis. The panel presented an industry study showing that if full power, land mobile, Class A and border stations are protected, 366 stations will not have a channel in 40 percent of the markets. Note that this doesn't mean that only 366 stations would have to share a channel, but rather it means a total of 732 stations would not have their own channel because those 366 stations without a channel would need another station to share with. Slide 12 in the presentation shows a map indicating areas where ALL stations must share a channel. They include western Washington, northern California, east central Florida, much of the Washington DC to Hartford corridor and much of the northeast border of the U.S. with Canada. Even Maine is impacted! One point the panel emphasized is that the FCC has to be very careful in relaxing interference requirements because interference ratio differences as small as 1 dB can make the difference between a watchable and unwatchable picture.

The presentations provide an excellent reality check for the OBI Technical Paper No. 3 – Options for Broadcast Spectrum, which I described as "biased, incomplete and in some ways, inaccurate" in a June 18 RF Report article.



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1.
Posted by: Brian Smith
Tue, 03-06-2010 07:03 PM Report Comment
Any talk of lossing channels 5 and 6 to radio?
2.
Posted by: Brian Smith
Thu, 17-01-2010 08:17 PM Report Comment
Doug Leng do you have an email I will send you a paper on spectrum efficient microwave
3.
Posted by: Brian Smith
Thu, 49-01-2010 08:49 PM Report Comment
The FCC and NTIA have papers going back as far as 1991 regarding efficient use of spectrum. Nothing has been developed to change that situation. Until real technical changes are made nothing will happen in broadband and TV network data delivery. Compression, delay and packet switching are only stop gap solutions. There are technical proven solutions but until the investment, and industry are prepared to listen and above understand the possibilities nothing will change regarding wireless spectrum solutions.




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