Dale Kelly wrote:
However, if your maps had the necessary information, he could likely give it a good start. Your maps lack: 1. Transmitter site locations and FCC antenna pattern and field intensities. 2. Longley-Rice predicted coverage maps, which are very important for determining underserved/unserved DTV areas and how they might best be covered.
Thanks, Dale. But the simpler answer, IMO, is that large area SFNs are a singularly bad idea for OTA TV distribution, where you want to cover the widest area possible at the lowest possible cost. Even along the California coast, I don't see why broadcasters would deliberately want to disenfranchise anyone living just slightly to the East of the coast line, just to obsessively go after this large area SFN idea.
I think large area SFNs, e.g. that nationwide SFN mentioned in the FCC document I pointed out recently, are just one manifestation of the egregious over-selling of COFDM that occurred a few years ago. Much like ATM (asynchronous transfer mode) was oversold by overzealous marketing types and their disciples in the 1990s. There's nothing wrong with either scheme, of course, just way too many misinformed promises, and too many people eager to Believe.
So when the dust settles, and real functioning systems are implemented, you don't notice anywhere near the differences among these systems as the hype was promising. It is surprising that when this basic reality is proving to be the case in the real world, it remains difficult to disabuse people of their old notions.
You also espouse the position that all broadcaster should multiplex from the same sites and use the example of how that is commonly done in Europe.
I'm not sure what all the issues are on this, but there are examples here in the US where towers are shared among broadcasters. The Empire State Buidling is one example, but there are others too. In this market, according to the FCC, WETA-DT (the new one, at 90 KW ERP), WUSA-DT, and WJLA-DT share the same tower (these are all UHF, btw). So somehow or other, this can be achieved. I think it's a good idea, when feasible, because it reduces the number of unsightly towers and it makes reception easier.
However, even in this, the European model is not all that different. There are oodles of examples where not all of the multiplexes can be received from the same azimuth, in the Italian DGTVi network. It's the rule rather than the exception. But what you notice over there is fixed antennas pointing in more than one direction, more often than rotors.
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