[time-nuts] Spec An for phase noise measurements

[Matt Ettus]

On Jan 21, 2008 11:44 AM, John Miles <jmiles at pop.net> wrote:
> > I am considering getting a new spectrum analyzer so I can make better
> > phase noise measurements than with my 8596E.  I've looked at the 8566B
> > and the 8562 and 8563 since I need coverage to at least 6 GHz.  The
> > 8566 is huge and ancient, though, so I think I'm leaning away from
> > that one.  Anybody have other suggestions?  Some of the Advantest
> > units seem to be reasonably priced on ebay, but it is hard to figure
> > out what their phase noise performance is.
>
> After working with a quadrature PLL/LNA, I feel very strongly that anyone
> who's serious about PN measurement should go this route.  I wasted a lot of
> time myself, sitting around wishing I could afford a quieter spectrum
> analyzer.  It's simply the wrong question to ask.
>
> It's true that the HP 8590s are among the noisiest spectrum analyzers out
> there, but the difference between the phase-noise floors of an 8596E and an
> 8560E is only about 20-25 dB.  The difference in cost is several thousand
> dollars.  If you invest in a nice 8662A instead -- or even an 8640B! -- you
> can use your *existing* 8596E to make measurements 30-40 dB below what even
> the 8560E series can do.


John,

I decided to get a new spectrum analyzer rather than an 11729 at this
time.  I bought an Advantest R3267 to replace the HP 8596E.  It seems
to have phase noise performance in the same neighborhood as the
8560-series, for about half the price.  In case I ever need anything
better, I can get an 11729 and use it with this analyzer, since it
goes down to 100 Hz, unlike the 8596 which only went to 9kHz.

I am seeing the following performance when measuring the built in 30
MHz reference:
100 Hz     -81dBc
1 kHz        -108 to -110
10 kHz      -117
100 kHz     -125
1 MHz        -131

All of those are 3-8dB better than the spec, except for at 1 MHz where
the spec is -135.  The measurements do jump around a bit.

I would really love to have PN.exe drive the analyzer so I can do real
phase noise plots.  I have an electronic copy of the manual, which has
all the GPIB info, but the last time I dove into the PN code (in an
aborted attempt to port it to Linux), I had a very hard time grokking
the code, plus I don't have a Windows development environment.  Is
there any way we can work together on getting this analyzer supported?
 Several other Advantest machines are compatible with it, so any work
would cover multiple models.

Thanks,
Matt