On Mon, Aug 5, 2013 at 5:53 PM, Stephen <ctx50...@centurytel.net> wrote:
> > Hi, > > I have a simple FM broadcast receiver flowgraph in c++ that causes > overruns. I'm using a B100 with a wbx daughter board. The flowgraph is > > usrp source -> lowpass filter -> quad demod -> deemphasis -> audio lp > filter -> constant multiply -> audio sink > > The sample rate is 250K. It works but after a couple of seconds the > overruns start. I've used much more complicated flowgraphs than this > with much higher sampling rates with out overruns. Looking at the cpu > utilization shows each core at less than 5%. Would anyone have any > suggestions for what to look at that could be causing the problem? > It's been called the "two-clock" problem. Basically, your soundcard's clock is decoupled from the USRP's clock, and neither is ideal -- they have error. As they drift apart either the audio clock will run slower (producing overruns) or faster (producing underruns). Here's an older discussion of the same issue. https://www.ruby-forum.com/topic/209464 A couple of seconds seems pretty fast, however. Make sure you're resampling the audio to a rate which is actually supported by your soundcard. --n > > thanks, > stephen > > > > _______________________________________________ > 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
