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

  • From: Craig Birkmaier <craig@xxxxxxxxx>
  • To: opendtv@xxxxxxxxxxxxx
  • Date: Tue, 15 Feb 2011 07:16:04 -0500

At 5:49 PM -0600 2/13/11, Manfredi, Albert E wrote:

Craig Birkmaier wrote:
 > This is ONLY true if we are talking about a market that exists in

 isolation - that is, it is sufficiently distant from any other market
 that one does not need to consider the loss of white space channels
 in adjacent markets.
No. It is true whenever you have adjacent markets that require overlapping coverage, such as cities up and down the East Coast. With single market SFNs, you continue to require white spaces in these cases. Once again, pay attention to real-world SFNs, the ones actually in existence, to see that this is how they are built.
Sorry Bert but what I wrote is true. The big sticks ARE the problem in areas where spectral reuse is most important, like the Washington to Boston corridor. Yes, any new network design will still need to consider interference, but the whole point is that SFN provide the tools needed to attain higher levels of reuse - (less white spaces).
If big stick frequencies can't be reused for 200 miles up and down the East Coast, by other high power big sticks, it is because THAT'S HOW BIG THE MARKETS ARE that they need to cover. Between Baltimore and NYC, Craig, the only major market is Philadelphia. NYC and Wash/Balt share many of the same frequencies. Why wouldn't they? What would SFNs do differently?
How absurd. It's only 200 miles from DC to NYC, and Philadelphia lies in between, not to mention a bunch of smaller markets. Washington and Baltimore are different markets, although you are in a location that can receive both - not because that is what broadcasters intend, but rather because their transmission technology is incapable of limiting the coverage of stations in a market to that market.
SFNs would provide far greater spectral reuse in the NE corridor, which could possibly result in: 

1. The ability to deliver the same number of programs in less spectrum.
2. The ability to deliver more channels in every market with the same or less spectrum. 
3. The ability to serve sub markets with unique content.
4. Less overlapping coverage with emissions into adjacent markets.

I wrote:


 > In the case of using SFNs in dense urban areas, there is NO way that

 big sticks or MFNs can provide the spectral efficiency of properly
 designed SFNs.
That's false. If the big stick needs to be supplemented, e.g. for more even coverage for mobile devices, it can be supplemented either by low power DOCRS, aimed downstream of the big stick, or by low power translators whose frequencies can be reused in the adjacent market, and match or exceed the spectral efficiency of a SFN. And certainly can be done with fewer towers and fewer compromised locations.
We disagree. Yes, there are many ways to slice and dice this debate. But the big sticks cause unnecessary problems, especially with respect to out of market emissions. SFNs provide the ability to control emissions so as to concentrate the signals within a market while providing more uniform power levels and better mobile reception. 

Regards
Craig


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