Hi Since you are dealing with two sources, both with random noise on them, there's no "easy" way to mathematically remove it.
Bob On Aug 25, 2012, at 1:02 PM, Tom Knox <[email protected]> wrote: > > It seems by collecting data while changing the loop time that hump or > knee could be mathematically removed, which with good quartz could be the > beginning of a very serious standard. > > Thomas Knox > > > >> Date: Sat, 25 Aug 2012 14:10:41 +0200 >> From: [email protected] >> To: [email protected] >> Subject: Re: [time-nuts] Rb short-term noise (was RE: Is this a cesium...) >> >> OK, so speeding up the disciplining will shift the hump on the left and >> rise it, while slowing down will shift to the right and lower it. > > It seems by collecting data while changing the loop time that hump or knee > could be mathematically removed, which with good quartz could be a beginning > of a very serious standard. >> >> On Sat, Aug 25, 2012 at 1:31 PM, Magnus Danielson < >> [email protected]> wrote: >> >>> On 08/24/2012 11:35 AM, Azelio Boriani wrote: >>> >>>> Magnus warned us about the use of very long time constant to act on >>>> disciplining. In my opinion it is better to use quieter data coming from a >>>> relatively fast sampling Kalman filter and correct as frequently as >>>> possible then train the filter with long time constants. >>>> >>> >>> It really, really depends. I usually warn about using _too_ long time >>> constants. As John has correctly pointed out, the PRS-10 has a good crystal >>> oscillator in it, allowing for longer time-constants to be used. >>> >>> There are many benefits of using an SC-cut crystal oven in a rubidium. >>> >>> I also agree with John about the hump, its bound to be there due to the >>> PLL action. There are two sources of humpiness at the cross-over. The first >>> is that at the cross-over you transition from the low-pass filtered >>> reference noise and the high-pass filtered oscillator and loop noise. Since >>> the noises is uncorrelated, their powers will add. The cross-over filter >>> does not suppress one noise before the other kicks in to sufficient degree >>> of suppressing the additive effect. Another aspect is that the PLL Q-value >>> creates a gain at the cross-over point, and using too low Q values acts >>> like an equalizer to bring noise up. >>> >>> This is to be expected and comes out of standard control system math. >>> >>> Cheers, >>> Magnus >>> >>> ______________________________**_________________ >>> time-nuts mailing list -- [email protected] >>> To unsubscribe, go to https://www.febo.com/cgi-bin/** >>> mailman/listinfo/time-nuts<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. _______________________________________________ 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.
