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

[Robert W McGwier]

We are giving away all the secrets.  The only secrets in SDR DSP are how 
to make a complex filter and how to overlap-NNN based convolution of an 
FIR.  All the rest is glue logic.

;-)

Bob


Charles Swiger wrote:
> On Fri, 2006-03-10 at 11:40 -0500, Bob McGwier N4HY wrote:
>   
> > I missed this question for 3 days.  
> >     
>
>
> it took 3 days to hit the list
>
>   
> > 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
> >
> >     
>
> Oh - found it - cool. There it is in blksimpl/wfm_rcv_pll.py:
>
>     stereo_carrier_filter_coeffs = gr.firdes.complex_band_pass(20.0,
>
> can make this beautiful response:
>
>     http://webpages.charter.net/cswiger/filter_response.jpg
>     
> Voila, single-sideband.
>
>
> BTW I recently fixed a broken decimation rate (11 -> 16) in Mike's
> examples apps/hf_radio - now is sounds much better.
>
>
> tks
> --Chuck
>
>
>   


--
Robert W. McGwier, Ph.D.
Center for Communications Research
805 Bunn Drive
Princeton, NJ 08540
(609)-924-4600