[time-nuts] Question about effect of spurious frequency modulation on Allan Deviation

Poul-Henning Kamp phk at phk.freebsd.dk
Mon Aug 6 01:24:29 EDT 2018


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In message <596c5939-d99e-0b01-7ff8-2b5194fc63dc at karlquist.com>, "Richard (Rick) Karlquist" writes:

>I need to measure ADEV on a source that has spurious
>sine wave frequency modulation on it.

The biggest factor is the ratio between the tau's
you do allan for, and the modulation frequency.

If modulation divides *cleanly* into tau and preferably
with a big factor, then you can ignore it.

Otherwise things get really messy and quite intractable.

Picking your taus as multiple of the modulation is usually the best strategy.

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Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
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