[USRP-users] Overrun on 56MHz with B210

Sylvain Munaut 246tnt at gmail.com
Mon Apr 20 15:03:03 EDT 2015


Hi,

> Incidentally, when it's overrunning, I can hear a high pitched
> capacitor noise inside of my laptop (Thinkpad W530, Intel i7-3820QM,
> C210 chipset), which is a bit funny. Is it possible that the system's
> USB controller is simply not up to task? Or is this a configuration
> issue I can address?

You might also want to try without fosphor, because maybe your GPU
isn't up to the task.

fosphor processes every input samples, it won't drop anything. But
that also means that if your GPU isn't fast enough, it won't consume
samples fast enough and the buffer will fill up and eventually the
'source' block will start dropping.

Usually this will also be accompanied by a sluggish fosphor
redraw/frame rate because it only redraws the screen when it managed
to empty the input buffer (which never happens if it's not fast
enough).

Have you tried the fosphor benchmark code ? What did it report ?

It might also be that the fosphor input buffer is too small. This has
been reported at high rates when working with 200 Msps with the X300.
In base_sink_c_impl.cc you can try to find "this->d_fifo = new fifo(2
* 1024 * 1024);" and increase it to (8 * 1024 * 1024).



Cheers,

   Sylvain




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