Re: [Discuss-gnuradio] first attempt at gnuradio - ssb phasing demod

[Bob McGwier N4HY]

I missed this question for 3 days.  Yes we do.  And here is how it works

It makes a real, low pass filter with cutoff

(H-L)/2

and then spins the coefficients to the correct frequency using a complex 
sinusoid.

It is used in a few places in usrp_wfm_rcv_pll.py

Bob



Charles Swiger wrote:

> On Sun, 2006-03-05 at 00:48 -0500, Robert McGwier wrote:
>  
>
> > Almost.  Translate the carrier to where you want it to be and then use a 
> > complex bandpass filter to pick off the sideband.
> >
> > make the filter edges    L  < H for your favorite bandwidth  (H-L)
> >
> > for USB,  make a complex filter   with edges  L, H
> >
> > for LSB, make a complex band pass filter with edges
> >
> > -H, -L
> >
> > Take the real part, make imaginary part = real part.
> >
> > send complex signal to sound card.
> >
> >    
>
> Do we have tools to make complex (negative freq) filter coeffecients?
> (other than externally in matlab etc).  I see 'optfir' but looks like
> it makes float taps too.
>
> --Chuck
>
>
>
>
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