It would be great to have the rds code inside the gnuradio tree instead of in a separate cgran project! ; )
I don't know why, but when I tried the cgran rds code, the grc example worked much better then the python one. Best regards, Rafael Diniz > > > Actually, I'm using the blks2 WBFM block, which I believe is a PLL > demodulator. > > Both of my "test" stations are actually roughly 100km > away from me, broadcasting from a high point in the Ottawa Valley. > > One > station comes in about 10dB stronger than the other, although both have > an ERP of about 100kW, and both are located on the same transmit tower. > > > I'll send you my 'stuff' once I'm more comfortable with it. The audio > quality is actually reasonably good, so I think the FM demodulator > portion is just fine. > > -Marcus > > On Fri, 24 Feb 2012 11:12:28 -0500, > Andrew Davis wrote: > >> I think the problems with SNR is with the FM > Demod, my car stereo can >> get RDS as the station fades 40 miles away, > but with my USRP has >> trouble picking up the stereo pilot from a 50kw > station one mile away >> ( -10dBm ). FM demod is hard for software ( I > think GNUradio just uses >> a zero-crossing detector ). >> >> Do you have > the code, I would love to test it. >> >> On Thu, Feb 23, 2012 at 11:33 > PM, Marcus D. Leech wrote: >>> I managed to get gr-rds built tonight, and > was able to test it planted inside my FM receiver. Even for a local > station, there are *lots* of errors, and more distant stations get even > more. I'm going to play around a bit with filter bandwidths, etc, to see > if I can improve it. Looking at the modulation technique, it's no big > surprise--they use a bi-phase baseband coding (basically like > differential Manchester), that drives a DSB-SC modulator with a carrier > at 57kHz. But that signal is generally about 20dB below the other audio > sub-channels on the FM demodulator output. So the SNR is generally > *terrible*. I'm rather surprised, after looking at it, that anyone > bother deploying RDS. It seems utterly crappy. It's generally broadcast > with fairly-low SNR, and there's no FEC built in, only CRC. I re-jigged > the XML for the demodulator part so you can reset the demodulator state > machine from within a GRC flow-graph (there was a reset() method on the > demod, but it wasn't exposed within the XML framework for GRC). Also, I > may re-jig the decoder portion--it currently injects decoded frames into > a message queue and to stdout. Might be useful to do other things with > those messages. Like is there a simple way to have a message dequeuer > within a GRC flow-graph so that one could stuff messages into a > variable? -- Principal Investigator Shirleys Bay Radio Astronomy > Consortium http://www.sbrac.org [1] > _______________________________________________ Discuss-gnuradio mailing > list Discuss-gnuradio@gnu.org [2] > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio [3] > > > > > Links: > ------ > [1] http://www.sbrac.org > [2] > mailto:Discuss-gnuradio@gnu.org > [3] > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > [4] > mailto:mle...@ripnet.com > _______________________________________________ > 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
