Hi Remember - most holdover specs also include a delta temperature (like 40 to 70C) during the holdover period ….
Bob > On Nov 5, 2016, at 12:15 PM, Bob Stewart <b...@evoria.net> wrote: > > Hi Scott and Bob and others, > I keep telling myself that I won't get involved with the temperature problem, > and yet for some reason I keep going down that rabbit hole. It seems to me > that it's one thing to correct well enough to stay on frequency within some > degree of accuracy, and yet another to try to also correct for phase. The > reality is that what I have is good enough for now. At 12 hours of holdover, > I'm usually a bit over 1uS out of phase. Maybe I could better that, but I > think I'll need a lot more understanding of the impact of aging vs > temperature before I can get there. > > Bob ----------------------------------------------------------------- > AE6RV.com > > GFS GPSDO list: > groups.yahoo.com/neo/groups/GFS-GPSDOs/info > > From: Scott Stobbe <scott.j.sto...@gmail.com> > To: Bob Stewart <b...@evoria.net>; Discussion of precise time and frequency > measurement <time-nuts@febo.com> > Sent: Saturday, November 5, 2016 10:54 AM > Subject: Re: [time-nuts] Thermal impact on OCXO > > Sounds like you already realized this. Phase is the integral of frequency and > the derivative of phase (phase rate) is frequency. So if you go from nominal > frequency - slow - nominal or equivalently nominal frequency - fast - nominal > the phase integrates up/down. > It would be a little more complicated for an ocxo since it is servoing the xo > temperature, you would need to know the disturbance rejection (gain, time > constant for a simple Pi controller) to try and feedfoward correct the phase > error. > > On Friday, 4 November 2016, Bob Stewart <b...@evoria.net> wrote: > > OK, never mind. I see the obvious. Phase changes faster at a higher > frequency than it does at a lower frequency. > > Bob > ----------------------------- ------------------------------ ------ > AE6RV.com > > GFS GPSDO list: > groups.yahoo.com/neo/groups/ GFS-GPSDOs/info > > From: Bob Stewart <b...@evoria.net> > To: Discussion of Precise Time and Frequency Measurement <time-nuts@febo.com> > Sent: Friday, November 4, 2016 8:56 PM > Subject: [time-nuts] Thermal impact on OCXO > > In the general case, is the impact of changing the ambient temperature around > an OCXO from, say, 40C to 41C the same as changing it from 41C to 40C all > else being equal? IOW, if I somehow have the same temperature ramp over the > same time period in both directions, will I wind up with the same frequency > and phase, or will the frequency revert but at some phase difference? > > Bob - AE6RV > ----------------------------- ------------------------------ ------ > AE6RV.com > > GFS GPSDO list: > groups.yahoo.com/neo/groups/ GFS-GPSDOs/info > ______________________________ _________________ > 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. > > > > > _______________________________________________ > 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.
