[time-nuts] How to measure performance of phase lock of synthesized PPS with Timelab??

[Erik Kaashoek]

I'm trying to record the phase error of a GPSDO capable of generating a
synthesized PPS (derived from the internal 10MHz and synced with GPS time)
To do this the synthesized PPS from the GPSDO is send to channel 1 of a
U6200A counter/timer and a 10MHz from a Rb is send to channel 2.
The U6200A is set to measure the time between channel 1 and channel 2.
The display shows the micro seconds between the PPS and the next 10 MHz
edge.
Timelab is set to acquire the data from the U6200A and the frequency is set
to 10MHz to have correct phase unwrapping.
How should the Data type of Timelab be set: Frequency or Time interval?
When I set timelab to interpret as Time interval the unwrapped phase
measurement drifts away when the time interval is a bit "low" meaning the
PPS is running behind. But as the measurement is already a phase
Any recommendations?
Erik.