Hello, I recently changed from UHD3.9 to UHD4.1 on an X310 + basic RX. I was surprised to find that without connecting a signal, a simple flowgraph of USRP source - complex to phase - buffer - file sink gives 0, without any noise. For comparison, the same flow graph on the same device in UHD3.9 records the phase noise from the unconnected RX channel. Anyone knows if any modifications in UHD could explain this behaviour ? Some kind of automatic resolution adjustment ? Or a change in default resolution ? Thanks a lot in advance. Cheers, Bess -- -- Bess FANG-SORTAIS (PhD) Astronome-Adjointe Laboratoire Temps Espace Observatoire de Paris 61 avenue de l'Observatoire 75014 Paris Tel: 01 40 51 22 91

Hi Bess, sorry for the late reply. 3.9 is a very old UHD version, so no one could answer this from the top of their heads. It's possible that we tweaked things that affect the relative levels, because so many things changed in the mean time. Which sampling rate are you operating at? Maybe this is related to the resampler. --M On Wed, May 28, 2025 at 4:23 PM Bess FANG <bess.fang@obspm.fr> wrote: > Hello, > > > I recently changed from UHD3.9 to UHD4.1 on an X310 + basic RX. I was > surprised to find that without connecting a signal, a simple flowgraph > of USRP source - complex to phase - buffer - file sink gives 0, without > any noise. For comparison, the same flow graph on the same device in > UHD3.9 records the phase noise from the unconnected RX channel. > > Anyone knows if any modifications in UHD could explain this behaviour ? > Some kind of automatic resolution adjustment ? Or a change in default > resolution ? > > Thanks a lot in advance. > > > Cheers, > > Bess > > -- > -- > Bess FANG-SORTAIS (PhD) > Astronome-Adjointe > Laboratoire Temps Espace > Observatoire de Paris > 61 avenue de l'Observatoire > 75014 Paris > > Tel: 01 40 51 22 91 > _______________________________________________ > USRP-users mailing list -- usrp-users@lists.ettus.com > To unsubscribe send an email to usrp-users-leave@lists.ettus.com >