[time-nuts] Any thoughts on best rubidium?

[Jim Lux]

On 9/23/11 10:54 AM, Brooke Clarke wrote:
> Hi Jim:
>
> Do you know how the HP/Agilent 4395A stacks up as a SA? I really like
> the true RMS power detection and the 1 Hz RBW (not video).
>
> <http://www.home.agilent.com/agilent/product.jspx?id=1000000864:epsg:pro&pageMode=OV&pid=1000000864:epsg:pro&lc=eng&ct=PRODUCT&cc=US&pselect=SR.PM-Search%20Results.Overview>
>
>

Not off hand.. I'm usually working at microwave frequencies and haven't 
used that particular one.

All of those spectrum analyzers with 1 Hz RBW are almost certainly doing 
some sort of FFT, and I assume the sample clocks are controlled such 
that you can hook up to some sort of external reference with 1E-9 kinds 
of stability.

The question might be whether the actual clock performance has good 
enough phase noise at 1 Hz offset to make the 1 Hz RBW meaningful. A 
-100dBc/Hz @ 1 Hz offset would be mighty impressive, no?

In fact, the specsheet shows of -95dBc/Hz at 1-100kHz offset.  The 
typical performance is better, of course, but still, it's about 
-90dBc/Hz at 100Hz offset.