[time-nuts] [Announce] Simulation software for powerlaw noise and PTP clock synchronization

[Wolfgang Wallner]

Hello Anders,

> Do you get agreement between PLN time-series and calcluated ADEVs, as per
> IEEE1139-2008 table B.2 ?

Yes, I explicitly cite IEEE1139-2008 table B.2 in my thesis. I will 
write a more detailed reply with example data later when I get home.

If you would like to try out the noise generations of libPLN: I also 
wrote a small command line utility for LibPLN, called PLN_Generator. You 
can find it in the Demo/ directoy [1].

> I tried [3] using python libraries colorednoise [1] (also based on
> Kasdin&Walter) and allantools [2], but it gives ADEVs that are
> systematically higher than predicted by theory. OTOH the calculated MDEVs
> seem to fall on the line that theory predicts. Image here:
> http://www.anderswallin.net/wp-content/uploads/2016/04/colorednoise-1.png

I have only used ADEV and AVAR so far, so I don't know about the 
MDEV-behavior of my simulated noise. I will try out your allan tools 
when I get home.

But the conversion between AVAR and power spectral density has been 
quite confusing for me, see [2] for an example. I thought I had figured 
it out at the end, but maybe I'm still wrong :)

> On your libPLN page the time-series graph is called 'time deviation' which
> could be a bit confusing as there is also an ADEV-like statistic called
> time deviation. Perhaps time-series or 'phase observations' or similar is
> better?

Yes, I agree that the wording is very unfortunate. IEEE 1139 first calls 
x(t) time fluctuations and time derivative, but later refers to it as 
time deviation in the text.

I only realized quite late that there is a name conflict with another 
statistic measure.

I guess the easiest solution would be to replace all occurrences of 
'time deviation' with e.g. 'time derivative'.

regards, Wolfgang

[1] https://github.com/w-wallner/libPLN/tree/master/Demos/PLN_Generator
[2] https://www.febo.com/pipermail/time-nuts/2015-March/091098.html