Hi
> On Jun 15, 2016, at 7:44 PM, Attila Kinali <att...@kinali.ch> wrote: > > On Wed, 15 Jun 2016 18:43:38 -0400 > Bob Camp <kb...@n1k.org> wrote: > >>> Same as above. >>> If you lock the VCXO to an OCXO, this will be much better. >> >> Each time you steer the OCXO to lock things up, you will degrade both it’s >> ADEV and it’s >> phase noise. If the GPS drops out when you do this …. the GPSDO never locks >> up. > > Yes, sure. The ADEV of an OCXO will turn upwards again at taus somehwere > around 10 to 1000 seconds. The loop bandwidth of the PLL that locks the OCXO > to GPS should be in the same range in order not to degrade the short term > stability of the OCXO. Also the PLL should have a rather damped behaviour > in order to average out the "phase jumps" resulting from the jitter of > the GPS PPS. > > If these two points are not taken care of, then yes, the ADEV, resp the > phase stability will degrate and thus can cause the GPS receiver to lose > track of the satellites. If you take data on the ADEV and phase noise of the OCXO during the initial lock / aggressive steering phase of the process … it’s a lot worse than a minor tip up at 100 seconds. Bob > > > Attila Kinali > -- > Malek's Law: > Any simple idea will be worded in the most complicated way. > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.