On 05/01/2020 01:35 PM, Jerrid Plymale via USRP-users wrote:
Brian,
Thank you for the quick response! I will try the DRAM FIFO and see if
that works. As I am working from home at the moment I do not have
access to a spectrum analyzer, Is there anyway I can use any of the QT
GUI blocks in gnuradio to determine a rough estimate? I know that the
values you set are just values and that you have to determine how they
correspond to actual values, but is there a way to do that
mathematically? Determining metrics for this project have definitely
been a struggle me so far.
Best Regards,
Jerrid
If you're using the multi_usrp interface via Gnu Radio, then the DRAM
FIFO won't be directly visible to you. What sample rate are you trying
to sustain? Can you share your flow-graph with us?
Underruns mean that your host CPU isn't "keeping up" with the
sample-rate demand from the X310, and if that is an ongoing thing, then no
amount of buffering will help.
*From:* Brian Padalino <bpadal...@gmail.com>
*Sent:* Friday, May 1, 2020 10:28 AM
*To:* Jerrid Plymale <jerrid.plym...@canyon-us.com>
*Cc:* usrp-users@lists.ettus.com
*Subject:* Re: [USRP-users] Setting up an X310 as a signal generator
On Fri, May 1, 2020 at 1:23 PM Jerrid Plymale via USRP-users
<usrp-users@lists.ettus.com <mailto:usrp-users@lists.ettus.com>> wrote:
Hello All,
So I have been trying to set up a USRP X310 as a signal generator
for about a week now, and I’m having some issues. Currently I am
using gnuradio-companion to develop the functionality. I have
three sets of signal sources that are of float type, creating the
I and Q values that get passed to a float to complex block. The
output of the three float to complex blocks go to an add block,
which then outputs to a USRP sink. Currently, the first problem is
with underruns, I’m not getting a lot of them however I am getting
breaks in the signal when I pass it to a second USRP X310. What
would be the best approach to make sure my signal is coming in
strong to the second USRP? I am also having issues with increasing
the power of the signal when it is received, is this mainly
controlled by the gain value on the USRP source in gnuradio? What
can I do to get my incoming signal to have more power?
You can try placing a DRAM FIFO in your transmit flow graph as the
first thing. That should ensure some tens of milliseconds worth of
buffering for your signals and allow for some host jitter without
underruns.
Do you have an external spectrum analyzer or something that can tell
you the power output of the first radio?
The receivers should be able to be saturated by your transmitter, so
there's definitely a gain issue somewhere.
Brian
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