Hi John/Robin: The calibration utilities rely on leakage across the RF switch. The newer UBX boards (rev C and later) have RF switches with much higher isolation. The benefit is a lot less leakage from TX onto RX. The drawback is that the calibration utilities will only work if you connect the TX/RX to the RX2 port with a 30 dB attenuator in line.
Regards, Michael On Thu, Apr 19, 2018 at 11:12 AM, Stanley, John P. via USRP-users < usrp-users@lists.ettus.com> wrote: > While uncalibrated LO leakage has never been great in the UBX for us, the > dc offset calibration procedure has given us adequate enough improvement. > We’re generally using offset tuning, but we still need that extra 15-20 dB > suppression we get from the calibration procedure. > > The issue we’re seeing with these newer Rev C boards, though, is that the > calibration doesn’t just fail to improve LO suppression; it actively makes > it worse. Offset tuning is pretty fruitless when the LO spur alone is >0 > dBm at the mid-point of available RF gain. > > > > > > *From: *ROBIN TORTORA <ti...@comcast.net> > *Reply-To: *ROBIN TORTORA <ti...@comcast.net> > *Date: *Thursday, April 19, 2018 at 1:44 PM > *To: *"Stanley, John P. via USRP-users" <usrp-users@lists.ettus.com>, > "Stanley, John P." <john.stan...@jhuapl.edu> > *Subject: *Re: [USRP-users] DC Offset Calibration Issue for Rev. C UBX-40 > daughter cards > > > > _______________________________________________ > USRP-users mailing list > USRP-users@lists.ettus.com > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com > >
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