Dear USRP and GnuRadio folks, My apologies... I thought I had specified that I am using B210.
Regards On Fri, Oct 12, 2018 at 9:52 PM Michael Dickens <michael.dick...@ettus.com> wrote: > Hi Ale - Reducing this query to just the USRP list since I'm guessing if > there is any issue its with that side of things. I'll reiterate Marcus' > query, and augment it. The performance depends on which USRP and which > version of UHD you're using. You didn't mention those. Scripts are > important (thanks!), but more info is required. Cheers! - MLD > > On Thu, Oct 11, 2018, at 1:03 PM, Mercado, Alejandra wrote: > > Dear USRP and GnuRadio folks, > > I'm not sure whom to whom I should address this question, since I don't > know if the problem arises in the GnuRadio code, the drivers, or the actual > physical USRP. > > I was attempting to run an extremely simple GRC graph (attached to this > email) where the input antenna of the USRP is grounded, the signal is taken > in with UHD: USRP Source, then the samples' magnitudes are squared, then > fed through a moving average (100,000 points), and then the result is > displayed on the screen in dB. > > As I altered the sampling rate, I observed a very strange thing: the > average for the noise readings were, by and large, smoothly increasing with > the sampling rate, except at certain frequencies (specifically, 30*2^k, > k=0,1,2,3, etc). At these specific sampling rates, the noise level would > shoot up by about 20 dB. > > I'm attaching a graph of the some of the values I got, where the big jumps > are marked by their respective sampling rates. > > Can someone explain why these jumps occur? I'm guessing that when I adjust > the samp_rate, it selects the front-end filter from a filter bank and > combines that with decimation. Maybe at certain samp_rates (30*2^k, > k=0,1,2,3,...) it's right at a threshold edge where the noise is worse. Or > maybe the problem is entirely at the other end and GnuRadio has a bug in > its assignment of samp_rate values? > > Two attachments included. Comments much appreciated. > > Thanks and regards, > Ale > > *_______________________________________________* > Discuss-gnuradio mailing list > discuss-gnura...@gnu.org > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > > Email had 2 attachments: > > - noise_level_unexpected.grc > 50k (application/octet-stream) > - Capture.JPG > 87k (image/jpeg) > > >
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