[USRP-users] buffer reset or clear issue on USRP N200

Luis Trigo ltrigo at gradiant.org
Tue Sep 24 14:27:35 EDT 2013


Josh Blum <josh at ...> writes:

> 
> 
> On 02/04/2013 12:38 PM, Chenfei Gao wrote:
> > Hi all,
> > 
> > I got a question on how to reset or clear the data stored in the
> > buffer of USRP N200. Is it possible to do it by rebooting the USRP ?
> > I set up a USRP receiver using uhd.usrp_source but I received a lot
> > of messages unexpected. I ran the receiver standalone. It can still
> > got the messages passing in without transmitter. Thus, I guess
> > something still stays in the buffer. Does anybody have the similar
> > situation?
> > 
> 
> The big hammer would be to power cycle the USRP, but...
> 
> The buffers should clear whenever the device object is constructed, also
> when the transmit or receive streamer is constructed.
> 
> If you dont want to tear-down and re-construct the rx streamer, you can
> simply issue a stop stream command (if this is continuous streaming),
> and call recv() until timeout. This will also flush out rx buffers.
> 
> Now the filters in the DSP chains do have history to them. So if you are
> having some issue with that, tx streams should be padded out at their
> end so the upconversion filters have zeros in their history; likewise,
> you an throw out the first several rx samples, which could be rx history
> from the last run.
> 
> -josh
> 
> > Any suggestions would be appreciated.
> > 
> > Chenfei
> > 
> > _______________________________________________ USRP-users mailing
> > list USRP-users at ... 
> > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
> > 
> 

Hi all,

I have a similar problem. I am working with the N210+XCVR2450 in a TDD 
application and, when I restart the RX streaming (with time spec) after the 
TX of a burst, the first RX samples are older than expected.

I suppose it is a buffer problem. I've tried different ways of cleaning the 
RX buffer, but I couldn't manage to do it in a propper way. Josh, what do 
you mean with "issue a stop stream command (if this is continuous 
streaming), and call recv() until timeout" ?

Thank you,

Luis





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