Here's a test of how to correct the 1PPS signal out of an F9T with the qErr-value from the UBX-TIM-TP message.
When the time-interval-counter is configured with start=reference-clock, stop=uBlox, the qErr is applied with a + sign to the measured time-interval - resulting in much smoother data for averaging times up to tau=1000s.
![](http://www.anderswallin.net/wp-content/uploads/2019/10/F9T_PPS_with_qErr_AW2019-10-10-1024x577.png)