[opendtv] Re: SFN response to Craig's post

The A-VSB demo didn't switch to SFN until we were close to those transmitters. 

TTFN,
Mark


Manfredi, Albert E wrote:

Craig Birkmaier wrote:


One thing that was not discussed much here was the SFN portion of
the AVSB demo.


Mark Schubin did talk about the SFN demo. He said that reception of the
signal from the three 100W transmitters in the SFN was as reliable as
reception from the big stick from Black Mountain, with the receivers in
use. Which is good news.

But the missing piece is, how did the coverage area differ? You can't
compare without that last bit of info.

Also, my guess is that the area covered by the 100W three-stick SFN was
very small compared with the area covered covered by the big stick. So
my reaction was, and is, that this is particularly good news for the big
stick. I mean, for the more typical broadcaster trying to cover a
typically huge US TV market, what better news than to say that the big
stick works just fine for mobile reception? As opposed to having to
deploy a forest of small sticks?

But really, you need coverage area comparisons, with ease of reception
as you move away from the big stick or from the SFN small sticks, to
draw any definitive conclusions. In Berlin and in Paris, there seems to
be no magic in terms of coverage area vs power of the SFN towers.

Maybe the lesson from DVB-T countries with DVB-H service is not mature
enough, and therefore invalid. It seems to me that it would be good to
improve mobile reception of regular 8T-VSB, e.g. using diversity
antennas, Doug's dynamic equalization from the data symbols (rather than
SRS), and perhaps even a truly backward compatible 1/3 rate turbo coded
stream for extra robustness in special cases. The fact that USB ATSC
receivers are somewhat popular is a pretty good indication that this
route would work. And is apparently echoed across the pond, with DVB-T
USB sticks, as opposed to DVB-H.

Another point not meant to offend anyone. If one is demoing a new
transmission mode of ATSC, e.g. MPH, is that organization going to be
incentivized to optimize 8T-VSB for mobility at the same time?

Bert
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