[time-nuts] Thunderbolt+PRS10+TAPR/TICC

[Forrest Christian (List Account)]

I am wanting some general advice on the following:

I currently have among my timing-related devices a couple of Trimble
Thunderbolts (a silver one w/ the inbuilt power supply and a gold flat
one), a PRS10, and a TAPR/TICC.

My current end goal is to use these to get an idea of the quality of the
1PPS output from various consumer (not timing) GPS receivers.   My thought
is to clock the TAPR/TICC from the PRS10, and then just capture the
relative timestamp of each 1PPS from the GPS receiver.   Using this, I
think I should be able to at least get a relatively good histogram of the
1PPS nanosecond phase error, and analyze the number of outliers/missing
pulses.  Possibly do some other analysis, but that would be a bonus.   Feel
free to correct my terminology if I've mangled it horribly.

My current plan is to mount one of the thunderbolts (probably the silver
one for electrical and mechanical reasons) and the PRS10 in a good quality
heatsink benchtop instrument case, and power it from a 24V charger+battery
array and leave it on permanently.      When not in use for the measurement
above, I'd just leave the 1PPS from the thunderbolt connected to the PRS10
and use that to discipline the PRS10 and use the outputs from the PRS10 for
day-to-day use.

However, when I'm doing the 1PPS measurement described above, it seems to
me that it is probably best for the PRS10 to be freerunning, to avoid any
contamination of the measurement by the PRS10 being disciplined.  (Feel
free to correct me if I'm wrong)

So my question is if the above seems like a reasonable course of action?
I also am curious about the best way to switch the PRS10 from disciplined
to freerunning/holdover to avoid any contamination from the disconnection
of the Thunderbolt.

Any other suggestions/hints for doing this type of measurement would be
helpful.   Assume I know just enough to be dangerous.

Thanks,

-forrest