[time-nuts] Keysight N5511A - phase noise measurements down to theoretical-177 dBm/Hz

[John Miles]

> My guess is well into 6 figure$.

It's a modular system like its 3048A and E5500-series forebears, so the only limits are your imagination and your bank account. :)  Very cool hardware, noting that it has some competition from all-in-one instruments like the FSWP that the earlier 'doomsday machines' didn't have to face.  

I'm sure you could spend a quarter of a million dollars on either the FSWP or the N5511A if you checked all the boxes.

> BTW, I don't know what -177 dBm/Hz has to do with phase noise.
> The relevant units are dBc/Hz as any time-nut knows.

I haven't seen PN analyzers rated that way before, but it makes sense to a certain extent.  They are basically saying they can measure the noise on a 0 dBm signal down to -177 dBc/Hz, with signals above 0 dBm being measurable with a commensurately-lower floor.  Their rated power limit is +20 dBm, so -197 dBc/Hz would be the theoretical limit.

The brochure goes into that in some detail, but there's no mention of cross-spectral collapse, which I thought was interesting.  The white-noise floor in their example plots is enviably flat, with no divots, suspicious-looking valleys or other artifacts.  If they are able to avoid that problem in the general case, it would be interesting to hear more about the strategy being used.

-- john, KE5FX
Miles Design LLC / Jackson Labs Technologies, Inc.