[opendtv] Re: Could be embarrassing...
- From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
- To: "opendtv@xxxxxxxxxxxxx" <opendtv@xxxxxxxxxxxxx>
- Date: Fri, 28 May 2010 18:25:37 -0500
Mike Tsinberg wrote:
> I watched DVB-T in a car in Europe. We were traveling through
> busy city. The reception was perfect. I never saw a glitch for
> 30 min we used that system.
That's because if you have an adequate guard interval, you automatically have
very good dynamic echo tolerance. We've been over all of this before, but since
we are being nostalgic ...
The frustrating part of this is that you can get that same level of dynamic
echo tolerance even with plain old 8-VSB, if the receivers were designed to
keep the incoming spectrum flat by averaging on just a few incoming symbols (as
proposed by Doug McDonald, Al Limber, and CB Patel). Since 8-VSB symbols occur
much more frequently than 8K COFDM, the time windows for averaging would be
very short. So the equalizer could keep up with dynamic echo without having to
wait for the training sequence.
You'd also want two antennas, to compensate for the really deep nulls. No
change to the ATSC standard.
Problem is, this is too easy. Where is the IP? Who gets the windfall? How do
the journals hype this up?
Bert
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