Re: [Discuss-gnuradio] Question about underrun

[Josh Blum]

On 04/16/2012 07:25 AM, Pan, Luyuan wrote:
> Hello everyone,
>      I am wondering what will the USRP and GnuRadio do if an underrun
> happens? i.e. The console/terminal print out U. Does the USRP restart
> again or the flow-graph restart? I now face the problem that USRP takes
> more time to transmit all the data out(I need to add time.sleep() to
> make sure all the data are sent out successfully), does it have some
> relation with the underrun.
>      Any suggestion is appreciated. Thank you for your help!

UHD docs about underflow:
http://files.ettus.com/uhd_docs/manual/html/general.html#overflow-underflow-notes

In terms of gnuradio, nothing happens. Gnuradio continues to push data
into the usrp sink block. Also, you can read the async message stream to
discover if an underflow event had occurred.

If you are using something newer than USRP1, I *highly* recommend using
the burst tags to schedule transmits, rather than timing
flowgraph.start() with a sleep.

-josh