[time-nuts] Method for comparing oscillators

Steve Rooke sar10538 at gmail.com
Thu Aug 6 13:12:58 UTC 2009


2009/8/7 Magnus Danielson <magnus at rubidium.dyndns.org>:
> Steve Rooke wrote:
>>
>> 2009/8/6 Magnus Danielson <magnus at rubidium.dyndns.org>:
>>>
>>> Ulrich Bangert wrote:
>>
>> ...
>>>>
>>>> Well, stability over time is what exacly is displayed in a
>>>> tau-sigma-diagram
>>>> of an oscillator. Since only a few words before he is saying that he is
>>>> NOT
>>>> intersted into Allan Deviation plots, then he is perhaps interested into
>>>> something else?
>>>
>>> Yes. Sigma-Tau plots of the Allan Deviation fame (with friends) addresses
>>> the instability of the noise part of things. For crystal oscillators and
>>> other non-atomic oscillators "linear" factors in frequency drift is not
>>> best
>>> specified, described or measured using that method, which was invented
>>> purely to be able to handle the phase noise side of things, not the slow
>>> frequency drift.
>>
>> For these sorts of measurements on drifting oscillators would it not
>> be prudent to use the Hadamard Deviation?
>
> Hadamard Deviation does not fully cancel the non-stable drift.



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