Re: [Discuss-gnuradio] atsc_cpll finally works

[Eric Blossom]

On Tue, May 20, 2008 at 09:38:21PM -0400, Charles Swiger wrote:
> 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.
> 
> --Chuck

Cool!  Glad to hear that it's working.

While you're at it, can you have it work with a sample rate of 8 MHz?
As I recall, you're currently using something like 6.1 or such, which
seems a bit narrow, given the roll off on the edges.

Eric