Re: [Discuss-gnuradio] underrun occurs when frequency changing

[Marcus D. Leech]

On 12/12/2011 01:41 PM, Yan Nie wrote:
> > > Really appreciate any of your suggestion!
> > Underrun is caused by your flow-graph not being able to provide samples to the 
> > hardware at the specified rate.  It looks to me like in
> >    your flow-graph above, your message-queue can easily get starved for new 
> > bits, and so the entire flow-graph stalls.  But that's just
> >    after a superficial inspection.  Since you actually *go to sleep* for an 
> > entire second, it seems like it would be pretty easy for the flow-graph
> >    to stall.
>   
> Thank you so much for your reply. I am wondering what the reason causes my message-queue could easily get starved for new bits? How to avoid this problem with my message-queue? Is the problem of the wrong setting about the msg_limit for the message-queue? I do not understand how to set the limit for msgq. What it depends on?
>
> I tried to make the  bits loading thread "sleep" for only 0.005s, though still 
> the underrun occurs. What is the reason of that?
>
> Thanks you so much for any of your suggestions.
>
> Thanks,
> Yan
You need to look at the flow of bits into your flow-graph, and make sure 
that flow can keep up with the sample-rate demanded by the
  rest of the flow-graph, right up to whatever you've programmed the 
hardware to do.



--
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org