alt Hacker NewsThat 'local TXDO' is most likely being governed by some kind of phase lock on the PPS or some other divisor and may well lead to terrible clock jitter in the short term while giving you insane precision over the longer term. Allan deviation plots made by a device clocked by a standard that is better than the one that you are checking is the only way to be sure how good (or bad) things really are.
I have a couple of GPSDOs here and it is fun to play them against each other, the differences in the short term can be substantial, but over anything more than a few days they are extremely accurate.
I'm aware, and yeah GPS is disciplining the TXCO, but I'm saying it's stable enough for non specialty uses outside of stuff like serving as a frequency reference. If you just want a clock source for NTP without the internet then all of this is already overkill.
You're also not likely to be out of GPS for particularly long stretches of time.