Re: [Discuss-gnuradio] gr-osmosdr issues ?

[Jean-Michel FRIEDT]

Thanks for the answers. All sampling rates are in the 1.5-2.5 MHz range,
namely 11025*128=1.4112 MHz when decoding POCSAG, or 48000*32=1.536 MHz when
decoding commercial FM (for these trivial tests). The issue about
synchronization only arises when an audio sink is used: sending the data to
a named pipe or scope sink displays the "PLL not locked" message but the
decoding/display look fine. I should emphasize that
rtl_fm -f 104.4e6 -M wbfm -s 200000 -r 48000 - | aplay -r 48k -f S16_LE
(running a friend's computer) works perfectly well, hence my concern about
gr-osmosdr at opposed to the RTL libs.

JM

> It's hardly a trivial report; RTL devices with gr-osmosdr are a very
> commonly used platform.
>
> I've seen similar messages from gqrx, but sound quality has not been
> impacted. My guess is that this may be related to rapid retuning for
> rtl devices, which basically involves not waiting for the PLL to lock.
>
> Does osmosdr-->nullsink display the same message?
> What about rtl_sdr ... > /dev null?
> Does this only happen at certain sample rates or at any rate? And are
> you using a supported sample rate?
> https://github.com/csete/gqrx/commit/d805c426f24f987cdb16e37bbab564d30da473c2
>
> On Mon, Jan 11, 2016 at 11:16 AM, jmfriedt
> <address@hidden> wrote:
> > My apologies for such a trivial bug report, but has anyone  
> > experienced issues with gr-osmosdr
> > "lately" (not sure when the problem started) about "PLL not locked"  
> > and data flow rate mismatch
> > in gnuradio data flows ?
> >
> > I have a couple dozen RTL2832U based dongles used for various SDR  
> > activities which have been
> > working quite flawlessly until this summer at least. Being  
> > currently in the process of preparing
> > the new teaching semester, I just discovered that *all* dongles  
> > (E4k, R820T or R820T2) experience
> > the same lack of PLL locking and data flow rate mismatch when  
> > connected to USB ports *on laptops*
> > (tested on four different laptop models, yet all running Debian/GNU  
> > Linux distributions, testing
> > and sid releases). The audio output in such a simple decoding  
> > stream as Osmosdr Source - Low pass
> > filter - WBFM decoder - audio output is not continuous and of very  
> > bad quality. The *same* dongles
> > connected to desktop setups with the same Debian/GNU Linux  
> > distribution exhibit no issue: stream
> > rate is consistent and sound quality excellent. Of course searching  
> > on the web for "PLL not locked"
> > yields a couple of million hits explaining that the tuned frequency  
> > range is not within the
> > bandwidth of the dongle VCO, which is not the case here.
> >
> > Has anyone seen reports of this issue before ?
> >
> > Thanks, JM
> >
> > --
> > JM Friedt, FEMTO-ST Time & Frequency/SENSeOR, 26 rue de l'Epitaphe,  
> > 25000 Besancon, France
> >
> > _______________________________________________
> > Discuss-gnuradio mailing list
> > address@hidden
> > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
>
>
>
> --
> GDB has a 'break' feature; why doesn't it have 'fix' too?



--
JM Friedt, FEMTO-ST Time & Frequency/SENSeOR, 26 rue de l'Epitaphe,  
25000 Besancon, France

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