[opendtv] Re: Charles Rhodes on SFNs
- From: "Allen Le Roy Limberg" <allimberg@xxxxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Mon, 28 Jun 2010 13:00:37 -0400
8-VSB receivers located in the regions of overlapping coverage areas would
require spatial-diversity antennas if SFNs were employed. This is an
expensive proposition and is impractical for hand-held receivers, lap-tops,
etc.
The alternative is for the 8-VSB transmitters to stagger their transmissions
in times, which provides no better spectrum utilization than with
disparate-frequency networks or SFNs using COFDM.
Al
----- Original Message -----
From: "Albert Manfredi" <albert.e.manfredi@xxxxxxxxxx>
To: <opendtv@xxxxxxxxxxxxx>
Sent: Sunday, June 27, 2010 11:01 PM
Subject: [opendtv] Re: Charles Rhodes on SFNs
>
> Craig Birkmaier wrote:
>
> > The distances between antenna sites for SFNs that
> > use the same channel for different content can be
> > significantly closer than 100 miles based on power
> > levels and emission masks.
>
> Maybe you are saying something different from what I interpreted
previously? Maybe what you're saying is that two single-market SFNs on a
given frequency channel can be placed closer together than the contours of
two big sticks? Meaning, the interference zone between the two Ch X coverage
areas can be reduced, if coverage is provided by SFNs?
>
> I covered that already multiple times, and so did Doug Lung. Remember what
he wrote. The SFN power density at the edges of the market cannot be any
lower than what it is with the big stick, or you will simply lose
viewership. So in fact, an interference zone will still exist, exactly where
you cannot have one. In these congested corridors, there are no significant
unpopulated areas.
>
> And even more importantly, what you are saying requires a dense mesh SFN.
Not the Euro variety SFN. Dense mesh SFNs, aside from being costly, are
iffy. They don't work well, even with DVB-T. With DVB-T2, the advantage is
that the towers can be spread apart further, which negates any potential
cookie cutter, sharp pattern advantage.
>
> So, a losing proposition all around. As the broadcasters reported to the
FCC, there are no significant spectrum advantages to single-market SFNs.
Ease of reception maybe, and I think that DOCRs, even with 8-VSB, should
help in difficult places.
>
> Bert
>
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