[time-nuts] Datum 9390 Rb phase noise

John Miles jmiles at pop.net
Sat Nov 17 21:25:09 EST 2007

> Yours is actually better than spec...  my Efratom FRS-C manual says the
> spec is -70 at 1 Hz offset, -110 at 100 Hz, -130 at 1 kHz.  The notation
> is a bit odd though -- it says "dBc/sqrt(Hz)".

You're looking at the Thunderbolt trace, I'm guessing... I'm only
getting -117 dBc/Hz at 1 kHz out of the Datum, -142 dBc/Hz at 1 kHz out of
the Thunderbolt.

> My understanding is that the compact telecom Rbs put FM on the reference
> as part of the lock mechanism; that makes the phase noise fairly ugly.

Hmm, yeah, that would do it!

Can anyone else measure the PN of one of these?  TVB, do you have anything
with an FRS-C in it?

-- john

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