[time-nuts] GPSDO Sigma Tau at large observation times
listertim at gmail.com
Wed Oct 5 17:29:29 EDT 2016
On Wed, Oct 5, 2016 at 11:01 AM, Tom Van Baak <tvb at leapsecond.com> wrote:
> Hello again Estanislao,
> 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.
> - 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.
> See also the examples here: http://leapsecond.com/pages/gpsdo/
Hi Tom, quick question: I've seen these plots before and they are very
useful to know what to aim at for GPSDO performance. Am I right in
thinking these were measured against a master - the page says " a very
stable 10 MHz reference. " without more details (unless I missed it)
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