Re: [Discuss-gnuradio] RDS demodulation

[mleech]

I'm not feeding it the stereo pilot.  I just use a fractional resampler to resample the few kHz at 19.0kHz/8 --this gives 4 samples/symbol into the DBPSK block.

The spectrum looks roughly correct--a double-humped structure either side of zero.

On Tue, 21 Feb 2012 12:27:54 -0500, Andrew Davis wrote:

> exactly 19.0kHz/8?
> Are you feeding it the stereo pilot or generating your own?
>
> Have you tried looking at the signal with an FFT scope to see if there
> is anything there or if it looks distorted or something?
>
> On Tue, Feb 21, 2012 at 10:35 AM,  <address@hidden> wrote:
> > I'm having trouble demodulating the RDS signal that comes along with a lot
> > of broadcast FM signals these days.  I know that there's "gr-rds" that has
> > already done this, but I wanted to do my own just for personal education.
> >
> > I spent a lot of time yesterday playing with it, and I can't get anything
> > but garbage bits out of the DBPSK demodulator in Gnu Radio.  I can't find a
> > freely-available version of the RDS standard, so I've been cribbing from the
> > nearly-impenetrable gr-rds implementation.
> >
> > What I've done is to carve off a few kHz around 57kHz out of the FM
> > demodulator, downconvert to zero Hz, and then resample to exactly 19.0kHz/8,
> > and feed that into a "Digital" DBPSK block, with symbols-per-sample=4.  I
> > get nothing but rubbish out the back side of this, even for a strong local
> > signal.
> >
> > Is there something I'm missing in the way the signal gets modulated?
> >
> > -Marcus
> >
> >
> >
> >
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