[time-nuts] DC Voltage Ramp?

Tom Van Baak tvb at leapsecond.com
Sun Sep 4 20:10:28 EDT 2005

Thanks for all the info on PLL types.

[ snip ]
> If you do Kalman filtering, it will change the tau as it learns the errors
> will perform better than any PLL since it will effectively adjust the tau
> the situation rather than some engineering decission had it a few years

Is there a readable reference on Kalman filtering
that doesn't require a PhD in math?

> If you do fancy PLL stuff, you can aid the PLL tracking with external
> so that temperature measurements, accelerometers etc. can be used to feed
> correction signals such that the PLL loop does not have to track it all in
> by itself. The gain of such a solution is that a wider range of PLL
> may be chosen.

I've seen OCXO with attached accelerometers - but
was told that they did not feed back into the PLL in
the expected way; instead if a jolt was detected it
would simply quickly shorten the PLL time constant
for a while. I suppose the same could be done to
detect high slew rates in temperature.

> So, there is alot more to do then just to "lock it up". The performance
you get
> certainly can be improved as a result.
> Cheers,
> Magnus

Thanks again for a great posting.


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