[time-nuts] Re: Repeatability of stability measurements

[Magnus Danielson]

Hi Hans-Georg,

You're MDEV slope is not that of white noise, but that of a (correlated) 
systematic damping. You have 1/tau^2 rather than expected 1/tau^1.5. 
Also, your levels are way off. This steeper slope for systematics is not 
widely documented by the way, but direct consequence of the math.

This is where I slip between the wrapped-phase (w) and unwrapped-phase 
(p) in TimeLab and figure out what is going wrong. That can be one hint.

Looking on your Frequency difference it may be that you have multiple 
slips. Could it be that you loose data-samples and thus the phase-slope 
jumps?

Here my main concern is the continuity of your data. That gives this 
kind of severly distorted plot that swamps the real measurement quickly, 
and is a sure give-away.

Cheers,
Magnus

On 2022-06-25 17:15, Hans-Georg Lehnard via time-nuts wrote:
> First of all the resolution factor from my first post is a copy error
> the correct value is 4.8828124999999998-11 (less decimal places). In the
> attached diagrams the correct factor was used.
>
> I generated testfiles with 2046,2047,2048,2049,2050 intervals, loaded
> into timelab and scaled them with 4.88281249999998-11.
>
> MDEV shows more noise as real measurements . Another testfile with 2000
> intervals and scaled with 5e-11 shows similar results.
>
> In the Frequenc difference plot you can see the difference grows
> stepwise with time. The zoom shows where the 2048 intervals are already
> in the next time step and the 2000 intervals are not yet. By zooming in
> you can also see this between the 2046 and 2050 intervals.
>
> Possibly an overflow or rounding error ?
>
> I think the overlap of this effect with the white noise of the real
> measurements creates my measured jumps.  More noise attenuates this
> step-like progression.
>
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