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Re: [Discuss-gnuradio] atsc_cpll finally works

From: Charles Swiger
Subject: Re: [Discuss-gnuradio] atsc_cpll finally works
Date: Tue, 20 May 2008 21:38:21 -0400

On Tue, 2008-05-20 at 21:00 -0400, Brian Padalino wrote:
> On Tue, May 20, 2008 at 8:52 PM, Charles Swiger <address@hidden> wrote:
> > 
> >  gr_complex IQ = input * gr_complex(a_cos,-a_sin);
> >
> > which would be necessary to handle negative frequencies I think.
> > 
> I don't know much about 8-VSB, but I was under the impression that
> it's a single sideband modulation scheme that benefits from being real
> only to avoid all the complex math associated with other modulation
> schemes.

The issue turned out to be jiggering the numbers that say "I strongly
suggest that you not mess with these..."   * by .707 for the bit timing
loop worked  ;)

We want a complex pll so it can take data directly from the usrp
centered on DC, w/o having to mix it up to 5.75e6 and converting to
real for the old fpll, which was just a trick to  look like the old
mc4020 adc boards.


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