On Fri, Jan 27, 2023 at 02:37:08PM -0500, Marcus D. Leech wrote: > On 27/01/2023 00:50, Mark-Jan Bastian wrote: > > > > When generating a complex +74 MHz and -73 MHz sinewave signal and adding > > them, > > I see 1 MHz spur about -30 dB @ -74 MHz, irrespective of LO frequency. Thus > > the > > spur might caused by (remaining) nonlinearity in the mixer or the > > subsequent stages. > > > > I would like to control the -30 dB spur to a lower value, or at least find > > out > > what the source of this spur is. > > Next thing could be the DAC, which supports rates up to 1600 MSPS, but is > > only used at > > 200 MSPS. Perhaps there is a way to modify the waveform in this step, > > similar in > > the way digital predistortion can help improve spectral output purity? > > > > Mark-Jan > > > > > Also, have you run these utilities: > > https://files.ettus.com/manual_archive/release_003_010_001_000/html/page_calibration.html
I'm quite sure the problem I see is caused by IQ imbalance. I can simulate it with the respective gnuradio block, with near identical results- asymetric spur, not symetric around a generated signal, for a whopping 0.5 factor. I did run the calibration tools on my new system, for rx and tx chains, but will run them again (iterate). If that doesnt help I might modify the sourcesignal, and follow the signal path again. Mark-Jan _______________________________________________ USRP-users mailing list -- [email protected] To unsubscribe send an email to [email protected]
