[opendtv] Re: Seeing Ghosts on a Single Frequency Network

At 12:54 AM -0500 2/7/11, Allen Le Roy Limberg wrote:
What the Sinclair submission could have made clear to the FCC is that investing in SFNs for broadcast DTV is not a particularly good idea, even if the transmitters in the SFN make simultaneous multiple-carrier-signal transmissions. Frequency-diverse simultaneous multiple-carrier-signal transmissions are more practical than simultaneous multiple-carrier-signal transmissions over SFNs, insofar as receivers capable of top-notch reception are concerned. The time and money investments in transmitters for frequency-diverse transmissions have been substantially sunk already.
When the SFN red herring is discounted, the controversy between single-carrier-signal transmissions and multiple-carrier-signal transmissions reverts to pretty much what it was before considering the networking of transmitters for them.
Assuming that Allen is correct, that multicarrier SFNs are not the best solution, one must ask what kind of spectral efficiency (i.e. reuse) can be achieved when multiple frequencies (channels) are used to deliver the same content?
I can see that one could checkerboard the transmission sites to deal with on-channel interference from adjacent markets, but it seems that to be really useful the power levels and antenna heights for each "cell" would need to be reduced, or we are in the same boat as today with large dead zones (white spaces) between used channels.
If this is the case we would actually reduce spectral efficiency by requiring more channels in a market to build an SFN. If we can make it work with more transmission sites at lower HAAT and power, then we have the same problem as exists for multicarrier SFNs - i.e. significant infrastructure costs to build out all of the sites... 

What are the trade-offs here?

I'm not seeing the benefits of the approach Allen is suggesting...

Regards
Craig


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