If I remember correctly, the original RDS feed the stereo pilot to the DBPSK block as it had the correct symbol phase. From this https://www.cgran.org/raw-attachment/wiki/RDS/rds.png it looks just like band passing the pilot and dividing to the correct rate.
On Tue, Feb 21, 2012 at 12:33 PM, <mle...@ripnet.com> wrote: > 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, <mle...@ripnet.com> 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 > > > > > _______________________________________________ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > > > _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
