Hi,
On 04/19/2016 07:46 AM, Wolfgang Wallner wrote:
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 :)
It depends. If you noises is true power-noises only and straight
additions of them, then mapping works. But this is not generically true,
so in generic there is no mapping guaranteed to work.
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'.
No. Keep Time deviation separate from TDEV and you are fine.
Cheers,
Magnus
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