[time-nuts] Ublox F9T tick to phase

[Demetrios Matsakis]

I have three F9T’s, which I set up to output PPS on one port and 10 MHz on the other.  All three showed periods of super-excellent consistency punctuated by several-ns jumps.  I saw these on an oscilloscope, and then put two F9T’s on a Keysight counter, with 50 ohms impedance, so I could plot them.  Their patterns were not the same in detail, and I’ve attached the one example.  This one shows much cleaner signals than the other one I looked at.  There has been some discussion of impedance on time-nuts, but this seems more like an internal frequency conversion issue.

Have any of you seen such things?

Also, it appears there is no way, with u-center2 ver 22.10.39687, to alter the PID values that go into generating these signals from GNSS.  Given that their internal oscillator can’t be of high quality, I guess it’s not very important.  But I’m curious. 

I posed the question to U-blox a question 2 weeks ago via a form, and they haven’t answered yet. (I might not have approached them the right way, though).  Anyhow, I’d like to ask if any of you know how to control F9T’s PID values?

Thanks, Demetrios