[time-nuts] New topics (was Re: He is a Time-Nut Troublemaker....)
Magnus Danielson
magnus at rubidium.dyndns.org
Tue Dec 23 18:03:06 UTC 2008
John Ackermann N8UR skrev:
> Magnus Danielson wrote:
>
>> This diffrential locking technique could be applied to atomic standards,
>> but then naturally require much improved solution than simple
>> oscillators. The diffrential locking technique does not magically solve
>> issues that is typically common mode, such as temperature dependence. It
>> can however even out individual properties like noise and systematic
>> drift to some extent. It essentially runs the oscillators as a common
>> constellation and attempts to achieve the average improvements of those
>> oscillators in an interlocked fashion. In its simplicity it will do
>> unweighed averaging. It is fairly easy to do weighed averaging by
>> individualizing the feedback gain to the respective oscillators. Further
>> refinements would individualize the proportional and integrate feedback
>> terms, but as always, the simplicity forms a limit.
>
> Assuming that the atomic standards are correct for some tolerance of
> "correct", I'm not sure why you would need to use a differential locking
> scheme (or anything else that moves one oscillator versus the other) --
> if you simply mix the two signals together you get a sum that contains
> both signals. Apart from redundancy (what if one unit fails), why not
> just use that sum to drive the clock?
Because they _WILL_ drift appart.
Interlocking them force them to a common frequency and average phase.
Cheers,
Magnus
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