[time-nuts] PM-to-AM noise conversion (was RE: New Question onHP3048A Phase Noise Test Set)
jmiles at pop.net
Thu Jan 17 14:21:19 EST 2008
Thinking about it a bit more, if your spur appears 6 dB too *low*, that
wouldn't be accounted for by the mixer-as-phase-detector correction factor.
It's in the wrong direction. Failure to apply that correction would make
your spur appear 6 dB too high.
Out of curiosity, does it matter which spectrum analyzer (3561A versus
3585A) you use to verify the spur amplitude?
-- john, KE5FX
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
> Behalf Of John Miles
> Sent: Thursday, January 17, 2008 10:54 AM
> To: Discussion of precise time and frequency measurement
> Subject: [time-nuts] PM-to-AM noise conversion (was RE: New Question
> onHP3048A Phase Noise Test Set)
> > I confirm the spur level on the spectrum analyzer. However the
> > 3048A always
> > says the spur is 6 dB lower than it actually is (6 dB
> plus/minus 0.5 dB).
> > Can anyone tell me why this is so.
> > I wondered if it had something to do with phase noise and
> amplitude noise
> > not being the same thing.
> That sounds likely. It's interesting to think about where that 6-dB fudge
> factor might be coming from...
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