[time-nuts] Thermal impact on OCXO

Scott Stobbe scott.j.stobbe at gmail.com
Sat Nov 5 11:54:14 EDT 2016


Sounds like you already realized this. Phase is the integral of frequency
and the derivative of phase (phase rate) is frequency. So if you go from
nominal frequency - slow - nominal or equivalently nominal frequency - fast
- nominal the phase integrates up/down.

It would be a little more complicated for an ocxo since it is servoing the
xo temperature, you would need to know the disturbance rejection (gain,
time constant for a simple Pi controller) to try and feedfoward correct the
phase error.

On Friday, 4 November 2016, Bob Stewart <bob at evoria.net> wrote:

> OK, never mind.  I see the obvious.  Phase changes faster at a higher
> frequency than it does at a lower frequency.
>
> Bob
>  -----------------------------------------------------------------
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>       From: Bob Stewart <bob at evoria.net <javascript:;>>
>  To: Discussion of Precise Time and Frequency Measurement <
> time-nuts at febo.com <javascript:;>>
>  Sent: Friday, November 4, 2016 8:56 PM
>  Subject: [time-nuts] Thermal impact on OCXO
>
> In the general case, is the impact of changing the ambient temperature
> around an OCXO from, say, 40C to 41C the same as changing it from 41C to
> 40C all else being equal?  IOW, if I somehow have the same temperature ramp
> over the same time period in both directions, will I wind up with the same
> frequency and phase, or will the frequency revert but at some phase
> difference?
>
> Bob - AE6RV
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