[time-nuts] Allan Deviation Calulations

[Magnus Danielson]

Sqrt(adev_meas^2-adev_ref^2) should do it, but you are close to the floor so confidence bounds will have to be small for meaningfull values.

Cheers,
Magnus

 Martyn Smith <martyn at ptsyst.com> skrev: 

Hello,

I'm trying to measure the Allan Deviation of an amplifier and need help with
the maths.

My measurement process uses the SR620 in time interval mode and I make one
measurement per second for about a day.

I then use Ulrichs excellent plotter to calculate the Allan Deviation.

The Allan Dev floor noise of the SR620 (without my amplifier) is as follows.

9.91E-13 (1 second)
1.59 E-13 (10 sec)
3.00 E-14 (100 sec)

I then add my amplifier into the measurement process.  I get the following
Allan Dev results

1.09E-12 (1 sec)
2.48E-13 (10 sec)
4.32E-14 (100 sec).

So the 1 sec Allan dev with my amp included, has gone up by 9.9E-14 for the
1 sec measurement.

How to I calculate the actual Allan Dev of my amp for the 1 sec period?

Best Regards

Martyn 


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