[time-nuts] Hadamard variance
magnus at rubidium.dyndns.org
Fri Apr 10 15:51:26 UTC 2009
Steve Rooke skrev:
> 2009/4/10 Bruce Griffiths <bruce.griffiths at xtra.co.nz>:
>> Just dont get too carried away.
>> Remember that the Hadamard deviation is only insensitive to linear
>> frequency drift.
>> If the drift is quadratic for example then it will affect the Hadamard
> Point well taken. In that case we need a new deviation measurement
> with 4 elements then :-)
Will not help to fully cancel the effect as crystal drift is a function
of log. See Vig on crystal oscillators at IEEE UFFC pages.
One needs to identify the drift shape, estimates its parameters and then
remove the estimated value from phase or frequency data.
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