[opendtv] Re: Bolivia TV standard mystery

  • From: Craig Birkmaier <craig@xxxxxxxxx>
  • To: opendtv@xxxxxxxxxxxxx
  • Date: Wed, 20 Dec 2006 09:21:43 -0500

At 9:10 PM -0500 12/19/06, Albert Manfredi wrote:
But I choked on this paragraph, back in page 26:

"Mobile and Single Frequency Network Operation. COFDM has an advantage in its ability to support large single frequency network operation and mobile operation over large geographic areas. For example, this would allow use of a single channel to provide the same programming concurrently over a very wide area, perhaps an entire country, and in this way could better support mobile service. In this regard, such an approach would avoid the problem of leaving the service area of an individual station during a program while travelling. This is the approach that some European countries are pursuing. However, to implement this approach in the United States would necessitate a substantial change to structure of the broadcast industry and the way it is regulated."

That's insane. Maybe this is why so many people are laboring under such misconceptions regarding SFNs and COFDM.

Nothing insane here Bert. It is you who are laboring under misconception about the U.S. broadcast model.

The problem is not related to the transmission infrastructure. It is related to the market-based structure used in the United States, versus the country-wide infrastructure used in most European nations. You could argue that a country in the EU is somewhat equivalent to a market in the United States, but the geographic scale is usually quite different.

The FCC is simply saying that our TV (and radio for that matter) broadcast systems are based around serving distinct markets. According to the Television Advertising Bureau (TVB http://www.tvb.org) There are now 210 unique markets in the United States. Gainesville is now ranked 162.

Thus, while it is possible to create nationwide single frequency networks, the reality for the U.S. is that any replacement infrastructure for TV distribution will be market based. Perhaps this is why you cannot get it through your thick head that the infrastructure I am advocating is not only possible, but desirable, as it would provide much higher spectral efficiency. To be specific, by limiting the signals to coverage of a market, rather than radiating into adjacent markets, channels can be re-used without the same concerns for market-into market interference that we have with both NTSC and ATSC today.

In densely populated areas where markets are closely spaced, the infrastructure would rely on a few sticks at relatively low HAAT and power, with a larger number of on-channel gap fillers. In the wide open spaces, we could still use big sticks and gap fillers to cover the pockets that can't receive the main signals. And in all areas we could have a portion of the channels reserved for sub-markets, providing the ability to deliver content targeted at that sub-market, which we cannot do effectively today.

This is why I was so distressed by your recent ranting about the infrastructure used in Europe - it is largely irrelevant compared to what would be used here in the U.S.

Bottom line, it is VERY FEASIBLE to build market-based SFNs in the U.S. that would be capable much higher spectral efficiency, and thus able to carry more bits, than the current ATSC big-stick infrastructure.

That being said, this is not likely to happen. What is more likely is that a watered down version of what I am proposing will be built using the spectrum recovered from broadcasters. Broadcasters will still be wasting huge chunks of spectrum, with the only "value" being that this wasteful luxury will make it very difficult for new competitors to get enough spectrum to compete effectively.


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