I've got some data that FEI released on g sensitivity enhancements in their OCXOs.
I'll dig it out. Rob Kimberley -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of John Ackermann N8UR Sent: 11 January 2011 6:58 PM To: Tom Van Baak; Discussion of precise time and frequency measurement Cc: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Sensitivity to g in atomic clocks FWIW, I have an FTS militarized Cesium that has an accelerometer as part of the OCXO assembly to reduce vibration sensitivity. I'm told -- but can't document -- that it was for the Navy and the idea was to counteract the effects of the ship's guns. FTS engineers had a couple of PTTI articles describing their accelerometer research. John On Jan 11, 2011, at 1:37 PM, "Tom Van Baak" <[email protected]> wrote: >> While sensitivity to g is an usually specified parameter for crystal >> oscillators, I've been unable to find any indications for atomic >> clocks, say 5071A, or more modestly LPRO. Can anybody point me to any >> source of info on the subject? >> Thanks, >> Antonio I8IOV > > Hi Antonio, > > You may find some information on g-sensitivity of rubidium in old FCS > or PTTI papers. There are high-rel rubidium for the military and space > applications, so practical issues of acceleration and jerk sensitivity > have been well researched. > > The other thing you could do is quickly and/or very slowly turn over a > running LPRO and report what happens. Like what we do with quartz, try > it on all three axis. It would be a fun experiment. > > For a 5071A the frequency shift is gh/c . Earth tides cause a couple > of ten cm change during the day; this change in local g affects the > output by parts in 10^17; way too low to be detected with a 5071A but > getting near to the capabilities of ion clocks. See: > http://www.nist.gov/pml/div688/clocks_092810.cfm > > For some info on g, tides, and clocks see: > http://www.leapsecond.com/hsn2006/ > > To detect changes in g with a 5071A you can raise the clock by many > meters. For example, g is about 9.808 m/s at sea level in Seattle but > 1 km up it's closer to 9.805 m/s . A 5071A runs about 1e-13 faster at > 1 km elevation compared to one at sea level. This is large enough to > be measurable. See: > http://www.leapsecond.com/great2005/ > > /tvb > > > > _______________________________________________ > 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. _______________________________________________ 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. _______________________________________________ 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.
