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Re: [Discuss-gnuradio] atsc signal plots

From: Charles Swiger
Subject: Re: [Discuss-gnuradio] atsc signal plots
Date: Sat, 06 May 2006 10:16:15 -0400

On Fri, 2006-05-05 at 14:45 -0700, Matt Ettus wrote:
> > The 2.0 port isn't doing as well - a few eyes show up here
> > and there:
> > 
> > http://webpages.charter.net/cswiger/g2_eq_data-1.jpg
> > 
> > and that's with the NOP equalizer. The LMS eq is all noise
> > all the time.
> To me it looks like the symbol timing tracker is not tracking properly.
> As the sample time shifts relative to the correct sample time you come
> in and out of alignment.  As I recall, the equalizer comes after the
> timing sync, so it won't work.  It needs proper symbol timing, and
> without it will actually make things worse.

Yep - looking at the 0.9 bit-timing-loop output:


vs a 2.x port of it shows something going wrong, using
the same input data:


could be something to do with differences in buffering,
scheduling, etc between gr0.9 and gr2.x.

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