[USRP-users] USRP under run when when trying to send messages in a low rate

Damindra Bandara damindra.bandara at gmail.com
Wed Mar 23 21:19:35 EDT 2016


Martin,

I do not know about end of burst packets. If possible could you please give
me more details on what I should do.

Thank you
Damindra

On Wed, Mar 23, 2016 at 1:46 PM, Martin Braun via USRP-users <
usrp-users at lists.ettus.com> wrote:

> Damindra,
>
> this looks like bursty transmission, are you sending end-of-burst packets?
>
>
> M
>
> On 03/22/2016 08:22 AM, Damindra Bandara via USRP-users wrote:
> > Hi Marcus,
> >
> > Thank you for getting back to me. Here is the description of my
> application.
> >
> > I want to get the user messages and transmit it via USRP. Since the
> > messages are infrequent I am use a beacon message to keep the message
> > stream  alive. I use QPSK as the modulation scheme. A beacon message is
> > transmitted in every second. At the receiving end I extract the
> > application level message and output it. I am using Etuss USRP N200 to
> > test the setup.
> >
> > The problem is that I do not receive the message at the other end. When
> > I observe the constellations at the receiver  it shows that the QPSK
> > demodulator does not remain synchronized. Also I observed  'UUUUUU'  at
> > the transmitter end.(which is due to an under run at the USRP).
> >
> >  If I transmit a file using this setup it works fine. But when I
> > transmit messages it is not transmitting.
> >
> > The transmitter end: application-->packet encoder --> QPSK modulator -->
> > USRP sink
> >
> > Receiver end: USRP source --> Synchronization blocks --> QPSK
> > demodulator  --> Packet decoder --> application
> >
> > Let me know if you need further information. I really appreciate if you
> > could help me to solve this issue.
> >
> > Thank you
> > Damindra
> >
> > On Tue, Mar 22, 2016 at 4:05 AM, Marcus Müller
> > <usrp-users at lists.ettus.com <mailto:usrp-users at lists.ettus.com>> wrote:
> >
> >     Hi Damindra,
> >
> >     it's a bit too much guesswork involved if you don't share *what*
> >     kind of application in GNU Radio you're designing. And a few
> >     parameters would be helpful too: something like sampling rate of the
> >     USRP, which USRP type you're using.
> >
> >     Generally, an underrun means your computer wasn't fast enough at
> >     providing samples to your USRP.
> >
> >     Best regards,
> >     Marcus
> >
> >
> >     On 22.03.2016 04:06, Damindra Bandara via USRP-users wrote:
> >>     Hi,
> >>
> >>     I am creating an application using GNURadio that transmits a
> >>     message every second. When I try to do this the transmit USRP
> >>     indicates that is is under run and I was not able to recover the
> >>     message at the receiving end.
> >>
> >>     When I use the same setup to transmit a file it works fine and
> >>     able to recover it.
> >>
> >>     Is there any procedure that should be followed when transmitting
> >>     infrequent messages? I appreciate if I could get any help.
> >>
> >>     Thank you
> >>     Damindra
> >>
> >>     --
> >>     Damindra Savithri Bandara,
> >>     PhD in Information Technology (Candidate)
> >>     George Mason University,
> >>     Fairfax,
> >>     Virginia
> >>
> >>
> >>     _______________________________________________
> >>     USRP-users mailing list
> >>     USRP-users at lists.ettus.com <mailto:USRP-users at lists.ettus.com>
> >>     http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
> >
> >
> >     _______________________________________________
> >     USRP-users mailing list
> >     USRP-users at lists.ettus.com <mailto:USRP-users at lists.ettus.com>
> >     http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
> >
> >
> >
> >
> > --
> > Damindra Savithri Bandara,
> > PhD in Information Technology (Candidate)
> > George Mason University,
> > Fairfax,
> > Virginia
> >
> >
> > _______________________________________________
> > USRP-users mailing list
> > USRP-users at lists.ettus.com
> > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
> >
>
>
> _______________________________________________
> USRP-users mailing list
> USRP-users at lists.ettus.com
> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>



-- 
Damindra Savithri Bandara,
PhD in Information Technology (Candidate)
George Mason University,
Fairfax,
Virginia
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.ettus.com/pipermail/usrp-users_lists.ettus.com/attachments/20160323/309b8ffb/attachment-0002.html>


More information about the USRP-users mailing list