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?
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