Hi again, I resolved my problem without using the Polyphase Resampler. It was a sample rate issue which did not match the requirements of the audio card. Anyway, thank you a lot for your help.
Francois Anoth wrote: > > Hi, > > I agree that it is a sample rate issue. The USRP sends too many data to > the computer which becomes overrun. As you said, I put a Polyphase > Resampler between the USRP and the WBFM receive blocks ( > http://old.nabble.com/file/p31046181/fm_receiver.py fm_receiver.py ). But, > when I execute the flow graph, I get this message : > > PCM name: hw:0,0 > Access types: > MMAP_INTERLEAVED YES > MMAP_NONINTERLEAVED NO > MMAP_COMPLEX NO > RW_INTERLEAVED YES > RW_NONINTERLEAVED NO > Formats: > S16_LE YES > Number of channels > min channels: 2 > max channels: 2 > 2 channels YES > Sample Rates: > min rate: 8000 (dir = 0) > max rate: 48000 (dir = 0) > 8000 YES > 16000 YES > 22050 YES > 32000 YES > 44100 YES > 48000 YES > 96000 NO > 192000 NO > audio_alsa_sink[hw:0,0]: using S16_LE >>>> gr_fir_ccf: using SSE > >>>> Done > > Nothing happens and I can no longer see the FFT sink window. By the way, > sorry for the delay of my response, but I have not worked on this project > for a couple of days. > > Francois > > > Tom Rondeau wrote: >> >> On Thu, Feb 24, 2011 at 10:28 PM, Anoth <francois.darr...@gmail.com> >> wrote: >>> >>> Yes, you must be right, I must have made a mistake when I set up the >>> flow >>> graph. How do you know the sample rate delivered by the UHD and how is >>> the >>> Polyphase Resampler implemented into the flow graph ? >>> >>> Francois >> >> Not entirely sure how to do this in GRC... When you set the sample >> rate of the UHD device, you can request back what it was actually set >> to using "get_samp_rate". So if you were doing this just in Python, >> you can have: >> >> req_sr = SR >> act_sr = uhd.get_samp_rate() >> resamp_rate = req_sr / act_sr >> resampler = blks2.pfb_arb_resampler(resamp_rate) >> >> Unless, of course, it's "resamp_rate = act_sr/req_sr". I've been >> working too long today to reason that out. >> >> I'm sure there is a way to do this in GRC by knowing the name of the >> UHD device and using it; I've just never done it. >> >> Tom >> >> >> >>> Tom Rondeau wrote: >>>> >>>> On Thu, Feb 24, 2011 at 7:17 PM, Anoth <francois.darr...@gmail.com> >>>> wrote: >>>>> >>>>> Hi Josh, >>>>> >>>>> Yes, I have already though about that and I tried to match the sample >>>>> and >>>>> sound card rates without success (but I might made a mistake). I have >>>>> also >>>>> read on the Internet that it might come from the sound card which >>>>> cannot >>>>> support all rates but I did not find anything more about that subject. >>>>> Here >>>>> the python code generated by GRC : >>>>> http://old.nabble.com/file/p31009164/wfm_rx.py wfm_rx.py >>>>> >>>>> Francois >>>> >>>> I think Josh is right and it's a sampling rate error. When you set the >>>> sampling rate of the USRP, ask the UHD driver what the current >>>> sampling rate is. Use what it returns to you to adjust the sampling >>>> rate properly. I ran into this same issue and solved it by using the >>>> pfb_arb_resampler block (Polyphase Resampler in GRC) to adjust the >>>> rates correctly. >>>> >>>> Tom >>>> >>>> >>>>> Josh Blum-2 wrote: >>>>>> >>>>>> >>>>>>>>>> gr_fir_ccc: using SSE >>>>>>> aUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaU >>>>>>> >>>>>> >>>>>> These characters being printed means that you have mismatched sample >>>>>> rates between your USRP device and sound card. Could this be the >>>>>> case? >>>>>> >>>>>> -josh >>>>>> >>>>>> _______________________________________________ >>>>>> Discuss-gnuradio mailing list >>>>>> Discuss-gnuradio@gnu.org >>>>>> http://lists.gnu.org/mailman/listinfo/discuss-gnuradio >>>>>> >>>>>> >>>>> >>>>> -- >>>>> View this message in context: >>>>> http://old.nabble.com/FM-Receiver-tp31009069p31009164.html >>>>> Sent from the GnuRadio mailing list archive at Nabble.com. >>>>> >>>>> >>>>> _______________________________________________ >>>>> Discuss-gnuradio mailing list >>>>> Discuss-gnuradio@gnu.org >>>>> http://lists.gnu.org/mailman/listinfo/discuss-gnuradio >>>>> >>>> >>>> _______________________________________________ >>>> Discuss-gnuradio mailing list >>>> Discuss-gnuradio@gnu.org >>>> http://lists.gnu.org/mailman/listinfo/discuss-gnuradio >>>> >>>> >>> >>> -- >>> View this message in context: >>> http://old.nabble.com/FM-Receiver-tp31009069p31010011.html >>> Sent from the GnuRadio mailing list archive at Nabble.com. >>> >>> >>> _______________________________________________ >>> Discuss-gnuradio mailing list >>> Discuss-gnuradio@gnu.org >>> http://lists.gnu.org/mailman/listinfo/discuss-gnuradio >>> >> >> _______________________________________________ >> Discuss-gnuradio mailing list >> Discuss-gnuradio@gnu.org >> http://lists.gnu.org/mailman/listinfo/discuss-gnuradio >> >> > > -- View this message in context: http://old.nabble.com/FM-Receiver-tp31009069p31046251.html Sent from the GnuRadio mailing list archive at Nabble.com. _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
