Re: [Discuss-gnuradio] solving u0u0 problems

[Marcus D. Leech]

>
> We are running on Ubuntu 10.10 64bit. What do you mean with type of
> sample rates? Maybe USRP decimation rate? I am changing fft-size based
> on this.
> So for 4MHz i am using 1088 fft-size and for 2MHz i am using 544MHz
> and I am getting the problem when running with 2MHz.
>
>   
I mean what sample rates--it sounds like 2Msps and 4Msps.

>> FFTW performance is often counter-intuitive.
>>     
> Can you explain this?
>   
FFTW uses a dynamic optimizer based on the FFT size.  If you're using an
FFT size that
  isn't a power of 2, it's rather hard to predict whether the resulting
FFT will be optimal
  or not.


>   
>> Are you using the default TPB scheduling?
>>     
> What is TPB scheduling? How can I find out more about scheduling? I
> never found something like this in the documentation.
>
>   
If you haven't touched it, then you're using TPB (Thread Per Block)
scheduling.

> First block is a stream to vector conversion. Then I am doing a number
> of operations on this vectors using standard GNUradio blocks as well
> as some custom made blocks.
>
> I still don't know what this u0u0 means and from which part of
> GNUradio it comes from. Is suppose it is some kind of buffer overflow
> between the blocks or something like that?
>   
uO means USRP overrun--the USRP is delivering data at a rate that is
faster than your flow-graph
  can keep up with, causing overruns.  The only way to cure this is to
reduce your sample rates,
  reduce your flow-graph computational complexity, or use a
higher-performance computer.




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