Re: [Discuss-gnuradio] Why does increased Samples per Symbol result in underruns?

[Eric Blossom]

On Mon, Jul 20, 2009 at 09:10:07PM -0500, Mir M. Ali wrote:
> Does that mean that the data being sent is lost or is it just that USRP is
> waiting for it to arrive?

uU means that there's a discontinuity in the transmitted burst.  The
USRP needed to transmit some data, but there was none to send.  The
receiver will not be able to demodulate the malformed burst.


> On Mon, Jul 20, 2009 at 6:30 PM, Eric Blossom <address@hidden> wrote:
> 
> > On Mon, Jul 20, 2009 at 05:29:02PM -0500, Mir M. Ali wrote:
> > > Hi,
> > > I used benchmark_tx.py with dbpsk modulation with Samples per symbol=7
> > and
> > > higher. I found that this resulted in lots of USRP underruns(uU). Why is
> > it
> > > so?
> >
> > You're doing more work per symbol.  The uU indicates that the host is
> > not sending data to the USRP fast enough.
> >
> > Eric