> Le 4 avr. 2016 à 05:39, Hal Murray <[email protected]> a écrit : > > > 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. >
I guess it is implementation dependent. I have observed this on Tbolt and PRS10 a while back but the graphs have transformed into unfindium. Something else on the redo list. I think what really happens is that the PPS lock is made on the nearest cycle when the GPS signal is recovered and then the frequency is adjusted using subsequent GPS data according to whatever the PLL/FLL constants were in effect at the time. So getting back to correct frequency could take a long time. > > -- > 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. "The main function of a modern police force is filling in forms." _______________________________________________ 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.
