One is do crystal oscillators change frequency when they are turned. The answer to that is yes. This gravitational acceleration effect is rather huge, parts in ten to the 9th or so, and anyone can see this. This is why you never touch, bump, or move, or rotate a laboratory frequency standard (this includes GPSDO and cesium standards).
And to give you a *picture* instead of just numbers... Here is a plot showing frequency changes in an OCXO (this from a free-running Thunderbolt GPSDO) over the span of one hour. Every 5 minutes or so I rotated the rectangular box on some axis by 90 degrees. <http://www.leapsecond.com/pages/ocxo-2g/TBolt-2g-6axis.gif> You can see that the sudden frequency jumps due to change in g-force on the crystal are about -0.5e-9 to +1.5 e-9, which is 100x the normal frequency noise for this oscillator (about 2e-11 pk-pk or about 2e-12 adev). Hopefully this result won't come as a big surprise to anyone; the so-called "2g turn-over" spec is common for quality oscillators. Again, this is why when you enter the world of precision timing at 1e-10 and below you tend not to ever touch your standards. Now if one of you happened to have a fully-programmable 3-axis turntable and a couple of hours you could slowly create a most beautiful high-resolution 3D color plot showing the precise shift in frequency as a function of axis. /tvb _______________________________________________ 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.