I'm using the SBX daughter board. I also misspoke, when I said no attenuation I was actually using a 10dB attenuator that I forgot about.
On Tue, Jul 17, 2018, 16:23 Marcus D. Leech <mle...@ripnet.com> wrote: > On 07/17/2018 03:10 PM, Müller, Marcus (CEL) wrote: > > Hm, I'd agree, with 60 dB attenuation, we should at least see reduced > > intermod products. OK, you said you had a spectrum analyzer that shows > > the spectrum without these spurs, so I'm trying to rule out TX > > overload/clipping: > > Can you use the screenshot function of that spectrum analyzer (or make > > a good photograph) with at most 100 kHz resolution bandwidth and a > > smaller step size on your SA? > > > > Thanks! > > Marcus Müller > Also, what daughtercard are you using here on your N210. > > Is it possible that while you were cabled direct without any attenuation > that the RX saw full-power from the TX? > > > > > > On Tue, 2018-07-17 at 14:49 -0400, Justin Shetty wrote: > >> I've tried the same test again with 30db and 60db of attenuation. The > >> average strength is lower but the FFT still has the same profile with > >> the repeated spurs. The RX overloading theory seemed promising, but > >> I'm not sure what to make of the situation now that attenuation had > >> little effect. > >> > >> On Tue, Jul 17, 2018 at 2:43 PM Justin Shetty <jas0...@gmail.com> > >> wrote: > >>> Looks the same as with my flowgraph (which is just the USRP source > >>> going straight to the constellation and fft sinks). Also for > >>> reference I'm using the SBX daughterboard. > >>> > >>> On Tue, Jul 17, 2018 at 1:13 PM Marcus D. Leech <mle...@ripnet.com> > >>> wrote: > >>>> On 07/16/2018 05:29 PM, Justin Shetty wrote: > >>>>> Hi all, > >>>>> > >>>>> I am working with an s-band radio and am receiving its OQPSK- > >>>>> modulated signal on an USRP N210. The signal I'm seeing on an > >>>>> FFT and constellation plot before any processing are not as > >>>>> expected though. It is very different from the example shown in > >>>>> the GNU Radio tutorial 7 (random source to a constellation > >>>>> modulator to a channel model). I also looked at the signal on a > >>>>> spectrum analyzer and it did not show the repeated peaks I am > >>>>> seeing on my FFT. Does anyone know where I might be going wrong > >>>>> or what's happening? > >>>>> > >>>>> Justin Shetty > >>>>> > >>>>> > >>>> What happens if you just use the "uhd_fft" utility to view this, > >>>> rather than your own code? > >>>> > >>>> > >>>> _______________________________________________ > >>>> Discuss-gnuradio mailing list > >>>> Discuss-gnuradio@gnu.org > >>>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > >> _______________________________________________ > >> Discuss-gnuradio mailing list > >> Discuss-gnuradio@gnu.org > >> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > >
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