Jackson Labs PHASE STATION 53100A, User Manual

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PhaseStation 53100A User’s Manual V1.04 25-Apr-2022 100
Show imaginary part of cross spectrum ( Ctrl-F3 )
Show estimated instrument noise ( F2 )
Phase noise and AM noise plots acquired with the PhaseStation 53100A, TimePod
5330A, and Symmetricom 512X analyzers can be displayed with a shaded area that
provides an estimate of the instrument noise floor, if you enable
Trace → Show
estimated instrument noise ( F2 ) .
In the 53100A’s case, the floor estimate is simply a heavily-smoothed rendition of the
imaginary portion of the cross-spectrum average shown by the
Show imaginary part of
cross spectrum ( Ctrl-F3 ) command. For more information about the imaginary cross
spectrum and the Ctrl-F3 command in particular, see “Understanding instrument spurs”
on page 69.
Use caution when relying on the noise-floor estimate. While reasonably accurate, it
may appear artificially high in the vicinity of instrument spurs. Conversely, certain
effects can raise the real measurement floor slightly above the shaded floor
estimate. As with ADEV measurements, the best way to obtain “proof of performance”
for analyzers in this class is to run residual tests at similar frequencies and signal levels.
Particularly when viewing multiple traces in
Display → Overlay (
o
)
mode, it may be
preferable to leave the floor display turned off in order to reduce display clutter.
Note that when Show imaginary part of cross spectrum ( Ctrl-F3 ) is active, the
File → Export ASCII AM/PM noise trace command will export the imaginary cross
spectrum trace data rather than the normal AM noise or phase noise trace.
Figure 46: Shaded noise floor estimate