Hi,
On 04/28/2014 07:56 PM, Артём Щербаков wrote:
Hello! I built a graph Allan Deviation. Correctly built them? How to know
the accuracy of time on them?
http://www.pictureshack.ru/view_71342_image_GPS_20140425.png
http://www.pictureshack.ru/view_96798_image_GPS_20140426.png
http://www.pictureshack.ru/view_34327_image_GPS_20140427.png
A few notes:
Your Y scale is in PPM, which might be handy for what you are doing, but
usually you use 10^-6 type of marking.
What kind of measurement is this? How was the data collected?
It looks like you are white phase modulation limited of quite severe
level. This makes me wonder how the data was collected and how it looks
before collected. If it has uncompensated wrappings etc it can look like
this.
I recommend you to pull down the TimeLab software, where you can acquire
data from an ASCII file. Make sure that you specify the distance between
the samples as well as the frequency (and thus period of unwrapping) and
it will unwrapp it for you. You can then view the data in unwrapped
phase (p), wrapped phase (w) and frequency (f) to see that your data
looks sane, then swap over to Allan deviation (a), modified Allan
deviation (m), Hadamard deviation (h) and Time deviation (t).
Cheers,
Magnus
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