[time-nuts] Is this correct ?

[Bob kb8tq]

Hi

If ADEV was a “narrowband” measure, you would be correct. Unfortunately ADEV looks at a 
wide range of frequencies so doing a single point analysis can be misleading. However the general
conclusion is often correct in the case of simple noise processes. 

One way to “get better” is to look at phase noise at 1 Hz or at 0.01 Hz. You then have a narrowband
measurement. Indeed you can say that the phase noise at 0.01 Hz isn’t going to get below the
best phase noise of the two sources. That *is* correct in all cases that I know of. 

Another approach is to use the Hadamard variance. It is a bit more “narrowband” and is a bit more
useful for crossover analyses. It’s still not as accurate as using phase noise. 

Bob

> On Apr 19, 2019, at 10:00 PM, Anton Moehammad via time-nuts <time-nuts at lists.febo.com> wrote:
> 
> Hi Everybody,excuse me for asking this question.
> 1. Let say I have a GPS receiver with 10 E-12 at Tau 100 second and I use it in GPSDO to control OCXO with 10 E-10 at Tau 100 second.The best I can get from this setup is 10 E-12 at Tau 100 second is this correct ? no matter how long I run my GPSDO (I disobey another factor that can influence stability)
> Thank YouAnton
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