[time-nuts] Interesting paper: Don't GPSD' your Rb...

[Azelio Boriani]

Well, so given the goal (stability at tau, for example) find the best
measure and adjust rates (maybe they are not the same) given the
oscillator-to-be-disciplined characteristics.

On Mon, May 7, 2012 at 11:44 PM, Magnus Danielson <
magnus at rubidium.dyndns.org> wrote:

> On 05/07/2012 10:59 PM, Azelio Boriani wrote:
>
>> Yes, interesting, now I realize... but:
>>
>>> the larger the deviation becomes and lower frequency it will have... and
>>>
>> both makes it>harder to suppress by filtering.
>>
>
>  Filtering at what level? Lengthen the sampling time? The average build up?
>> That is, now I'm not aware and think that I have to correct as slowly as
>> possible because I think that the oscillator has to be disturbed to a
>> minimum. Then I see low frequency large deviations, so I think, OK, I have
>> to average longer to account for. Is this the filtering you are referring
>> to? So that one ends up increasing the slowness of the system getting only
>> very slow frequency very large deviations.
>> Thanks for the help
>>
>
> If you have a little frequency error the longer you wait to do any
> adjustment the larger phase-deviation that frequency error will result in.
> If you sample to seldom, then you rely on your DAC resolution and stability
> inbetween your samples, the clock will essentially be in hold-over. If this
> is 1 ms, 1 s or 1000 s will make a difference.
>
> That relates to sampling rate, which puts a limit to the loop bandwidth
> you can have.
>
> But my main reaction was to the sample-rate vs. measure and adjust rate
> (i.e. sample rate), and I wanted to point out that there is a merit in
> sampling (much) faster. The modulation waveform is only to illustrate the
> averaging behaviour.
>
> Cheers,
> Magnus
>
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