[time-nuts] GPSDO Sigma Tau at large observation times

[Attila Kinali]

On Wed, 5 Oct 2016 11:01:36 -0700
"Tom Van Baak" <tvb at LeapSecond.com> wrote:

> Nice set of questions. The short answer is that for a GPSDO,
> - The left side of the ADEV plot will show the difference between the quality of the local oscillator, in your case TCXO vs. OCXO vs. Rb. 
> - The middle of the ADEV plot will show the difference in the choice of time-constant or the environmental conditions during the test.
> - The right side of the ADEV will show the quality of the GPS timing receiver.
> 
> Also,
> - The left side of the ADEV plot may expose limitations in your measurement equipment or the local low-noise reference that you're using.
> - The right side of the ADEV plot may expose limitations in your local frequency reference. A cesium or H-maser helps here. If you use one GPSDO to test another GPSDO the very right side of the ADEV plot is misleading.

Additional to this, I recommend having a look at Enrico's Chart[1].
It lables all the slopes in the different forms we measure stability
and what noise type they represent, and also their relationship.

			Attila Kinali


[1] http://rubiola.org/pdf-static/Enrico's-chart-EFTS.pdf


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