Re: [Discuss-gnuradio] Question about carrier syncronization fordemodulating QPSK/BPSK signal.

[Matt Ettus]

Eric Blossom wrote:

> On Thu, Jun 01, 2006 at 08:54:28AM -0400, Tom Rondeau wrote:
>  
>
> > Set the
> > alpha value somewhere around 0.005 - 0.05 to get started (and play with it
> > from there). The beta value should be about an order of magnitude smaller
> > (it's been set to 0.25*alpha^2; I'm not sure where that comes from, though).
> > The next two arguments are the max and min frequency deviation in terms of
> > scaled frequency, so 0.05 and -0.05 work well. The final value of the
> > reference phase can just be set to 0. This block's been around for a bit of
> > time and used in BPSK.
> >
> >    
beta = alpha^2/4 gives a critically damped loop.

> > > From here, you'll need to worry about symbol synchronization. We build a
> > complex modified Mueller and Muller clock recovery circuit for this called
> > gr_clock_recovery_mm_cc (this file existed already, but we modified it
> > some). Set mu=0.05, omega is approximately the samples per baud,
> > gain_mu=0.05, gain_omega=0.25*mu^2, and omega_rel_limit=0.5. These values
> > will get you started.
> >    
Same way of setting beta here.

Matt