[USRP-users] Detect and react to underflow in gnu radio

Martin Braun martin.braun at ettus.com
Fri Oct 2 12:22:58 EDT 2015

On 01.10.2015 15:09, Dennis Zollo via USRP-users wrote:
> Hello users,
> I am trying to detect the 'U' and 'L'  (underflow & late packet)
> messages from transmit on a USRP b210 connected over USB 3.0 and
> controlled by gnu radio and python.  I would merely like to know
> programmatically that a U or L has occurred and react.  In our case,
> this means we should halt our test and invalidate the results. 
> Does someone have an example of how to do this?  Should I be using the
> asynch message source block?  Should I be registering a stdout callback
> through the C++ api?

If you're in GNU Radio, you can use the async message block. The only
problem is that is uses the legacy message queue model, but it's better
than parsing output.

> Also, what are some strategies to avoid these "late packet" or
> "underflow" errors and or tune them out of a system?

Underflow is hard to avoid (other than beefing up your system), late
packets can usually be avoided, though. What's causing them in your setup?


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