[time-nuts] Why discipline Rubidium oscillator?

Jerry Hancock jerry at hanler.com
Mon Nov 20 13:34:07 EST 2017

I know this is going to sound dumb as I know many GPSDOs had rubidium oscillators in them.  I can see why, in that during holdover, they would tend to be more stable vs others, but given that there is a direct mathematical relationship between the rubidium frequency and potentially the 10Mhz desired output frequency, why do they have to be disciplined or better yet, what advantage does it bring?  Also, I can see how you discipline a DOCXO with the external voltage, how do you discipline a rubidium?  Pulse stretching?  

I guess I don’t understand how the technology works, but it seems like an RF signal is swept that would be used to detect a dip at a pretty well defined frequency.  This dip can be used to discipline the oscillator to something like 9Ghz or a factor of what, 900+ times better than 10Mhz.  So wouldn’t that be able to get your desired 10Mhz to 10,000,000.001 or pretty much my level of measurement?  Or does is the dip not quite that precise?  If you can point me to a write-up on this I’ll go away.

Thanks to Gilbert for providing me with at least one rubidium oscillator that is working out of 5 though 2 others seems to stay locked for a few hours during my testing.


More information about the time-nuts mailing list