[time-nuts] HP phase-noise measurement seminar coursebook
brooke at pacific.net
Sun Sep 23 15:02:16 EDT 2007
Some recollections and comments after reading the seminar paper.
When making automated mixer spur measurements using the HP 8566 spectrum
analyzer and HP 8350B sweep generators, both under HP-IB control the phase
noise of the 8350B was so bad you could not make a measurement. With the RBW
set very side you see just a line but as the RBW is narrowed down you start to
see the filter shape and at narrower settings you see gibberish because the
signal has FM noise. Switching to synthesized sources allowed the RBW to be
narrow enough to get the noise floor down where it needed to be to see the
spurs. That eye opener was my introduction to phase noise.
In the Phase Noise paper you'll notice that for a number of measurements the
11729B is needed in addition to the 3047 and that when this is done often the
automatic features of the 3047 are not used. I.e. you don't need the 3047 for
those measurements. I ended up rolling my own automated phase noise systems
based on the information in the 11729B manual that had an 11729B (usually with
all the optional bands installed just to avoid chasing down the one that was
needed) and one of the good phase noise HP signal generators along with the
Rocky Mountain Basic computer. All this would fit a 4 foot tall rack on
wheels. Made a number of them.
When talking about the straight spectrum analyzer method of measuring phase
noise they discount the non synthesized analog spectrum analyzers and focus on
the synthesized analog SAs. But what's not mentioned are the synthesized
digital spectrum analyzers like the HP 4395 and 4396. These have true 1 Hz RBW
settings and also have true RMS signal detection that avoids the corrections
that are needed when an analog SA is used BUT they are not mentioned in the
paper. I think this is because they are made in the Kobe, Japan division of HP
and are not U.S. made products. Kobe is also where the LCR meters and
impedance analyzers come from.
I've downloaded your Phase Noise software but have not yet tried it out on my
I think all that's needed is to enter 0 dB into the Noise Response window
instead of the +2.5 db for a peak detector and -0.5 db for RBW correction
needed for analog SAs.
http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Cam
John Miles wrote:
> ); SAEximRunCond expanded to false
> Errors-To: time-nuts-bounces+brooke=pacific.net at febo.com RETRY
> This seminar was given June 14, 1985 at Red Bank, NJ. Its handout covered
> pretty much every bit of information and lore HP had to impart on
> phase-noise measurement. Anyone interested in PN measurement with 80s-era
> hardware (8566/8568/3585A, 11729B/C, 3047A, etc.) may want to download a
> copy of the course notes that I just scanned.
> http://www.ke5fx.com/HP_PN_seminar.pdf (124 pages, 7 MB)
> -- john, KE5FX
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