On Thu, 29 Oct 2009 17:03:34 +0100, Edward Jensen wrote:

> Hi.
> 
> I'm trying to understand the concept of Allan variance with applications
> to gyroscope data. I have read a lot of articles in which they use the
> Allan variance to decompose the variance into different random processes
> (random walk, bias white noise and so on). I have, however, not found
> any articles where they actually explain how this is possible and how it
> works (with regards to the different slopes in the Allan plot).
> 
> Can anyway point me to where this information can be obtained? Books or
> articles.
> 
> Thanks in advance.
> Edward.

Go to the source?  http://www.allanstime.com/AllanVariance/.

Somewhere on that site he refers to a paper he did for HP before HP 
became a name for a crappy computer.  It has some curves for time bases 
that are pretty meaningful for what you want to know.

-- 
www.wescottdesign.com

>Hi.
>
>I'm trying to understand the concept of Allan variance with applications
to 
>gyroscope data. I have read a lot of articles in which they use the Allan

>variance to decompose the variance into different random processes
(random 
>walk, bias white noise and so on). I have, however, not found any
articles 
>where they actually explain how this is possible and how it works (with 
>regards to the different slopes in the Allan plot).
>
>Can anyway point me to where this information can be obtained? Books or 
>articles.
>
>Thanks in advance.
>Edward. 

If you have IEEE access, check out standard 952-1997.  It's for IFOG's,
but is applicable elsewhere, I think, and directly answers your question:

http://standards.ieee.org/reading/ieee/std_public/new_desc/aeroelect/952-1997.html

What sort of gyros do you have in mind?  On the MEMS ones I have (11 hour
test, about as long as I was willing to babysit), the big contributors are
white noise, bias instability, and possibly some other unidentified junk. 
I've never succeeded in getting quantization to show up properly on an
Allan variance plot, either in simulation or with real data, so I may be
doing it wrong.  For a beginner's primer, you might also check out these
app notes:

http://www.xbow.com/support/Support_pdf_files/Bias_Stability_Measurement.pdf

http://www.xbow.com/support/support_pdf_files/anglerandomwalkappnote.pdf

Some of the analog devices MEMS parts also have RAV plots.

Hi.

I'm trying to understand the concept of Allan variance with applications to 
gyroscope data. I have read a lot of articles in which they use the Allan 
variance to decompose the variance into different random processes (random 
walk, bias white noise and so on). I have, however, not found any articles 
where they actually explain how this is possible and how it works (with 
regards to the different slopes in the Allan plot).

Can anyway point me to where this information can be obtained? Books or 
articles.

Thanks in advance.
Edward.