On 3/31/22 2:40 PM, Bob kb8tq wrote:
Hi
The gotcha of looking at one GPSDO against another is that
the GPS side of things is “common mode” to all of the devices.
Bob
We all know that GPS is "truth" and has no errors, common or otherwise
<grin>...
But seriously, three cornered hats work best if all the sources have
similar statistics, but say you compare 2 GPSDOs against OCXO, even if
the OCXO is an order of magnitude or two worse (at long tau), where does
it fall in the "trying to discipline a wet noodle" territory.
One might also be able to do different tau ranges - GPS is not so hot in
the short run (1000 seconds) but is quite good in the long run (days),
while an OCXO is the reverse (which is why we make GPSDOs at all). So,
if you're looking to measure the performance of a new GPSDO, can one do
two sets of measurements - one against OCXO and one against GPS, and
then see how you do against each of the component curves. After all,
the hope is that the GPSDO is better than either of the other two.
_______________________________________________
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an
email to time-nuts-le...@lists.febo.com
To unsubscribe, go to and follow the instructions there.
