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

Josh Blum josh at ettus.com
Mon Feb 4 13:46:24 EST 2013



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
> 
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