Hej Bruce, >>> The good news is that if you, the time-nut, have the gear and >>> the time to measure the stability of the OCXO in your GPSDO, >>> and know your environment well, then you can probably safely >>> lengthen the TC and achieve much better mid-term stability out >>> of your GPSDO as shown in the plot above. >>> >> Agreed. But also recall that long-term effects like frequency drift is >> pretty easy to measure with a GPS. It would not take too much research >> to figure out some suitable drift-TC relationship such that you could >> either just look the charts to find a good match or even apply them in >> real time steering. >> >> For ThunderBolt owners it is pretty straightforward to adjust the TC and >> damping, which is very nice. Use this oppertunity! > > How exactly can one measure the resultant performance or even select the > optimum time constant and damping factor if one doesn't have a quieter > reference? > Can one really resort to some sort of N cornered hat?
If time constants is allowed to be limited by frequency drift (regardless of its source) then you can use a long term drift estimate to control the time constant of the control loop. Essentially being an adaptive filter. It is still a gross oversimplification, but may still be a handy one. Cheers, Magnus _______________________________________________ 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.
