Hi On a surplus cell phone GPSDO it’s going to be:
1) System has been down for a while (= something failed) 2) System is now working ( = something was fixed) 3) The primary system spec must now be met (+/- 100 ns time alignment). 4) The secondary system spec should be met (+/- 5x10^-8 frequency) 5) Get it done now. Both the time alignment and frequency specs are highly system dependent. The time offset is likely to be aligned in a modulo 100 ns step. It then is fine tuned over some time period to take out the rest of the error. If it’s done over a 50 second period, they can do it at a 1x10^-9 frequency offset (but probably don’t …. more likely it’s a higher offset at the start of the period). Bob > On Apr 3, 2016, at 11:39 PM, Hal Murray <[email protected]> wrote: > > > Has anybody studied what happens when a GPSDO comes out of holdover? Has > anybody seen any specs? I don't think I have. > > I think you have a choice of quick recovery for time or frequency, but you > can't get both. > > Suppose your setup has been in holdover for a while. The frequency is > slightly off. The time offset of the PPS pulse will be the integral of the > frequency offset. > > What happens when you come out of holdover? If you fix the frequency, the > PPS will stay off. > > Suppose the PPS has drifted by 1 ns. If you correct that in 1 second, the > frequency will need to be off by 1E9 during that second. > > > -- > These are my opinions. I hate spam. > > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
