Jackson Labs PHASE STATION 53100A, User Manual

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PhaseStation 53100A User’s Manual V1.04 25-Apr-2022 92
When used in the Measurement → Frequency difference ( f ) view, the effect of
Trace → Phase/frequency traces begin at zero ( z ) is somewhat similar to applying
Edit → Subtract global linear phase trend (frequency offset) ( Ctrl-o ) to each visible plot.
It’s not quite the same, though, because a trace’s first data point is not necessarily
anywhere near its trend line. Subtracting the trend will often do a better job at
centering individual traces symmetrically about the Y axis, as seen below.
Of course, Edit → Subtract global linear phase trend (frequency offset) ( Ctrl-o ) has the
drawback of altering the selected plot’s phase data record and removing potentially
useful information (namely the phase trendline). Fortunately, there’s also a non-
destructive global option that has the same visual effect,
Trace → Show linear
phase/frequency residual (
r
)
:
These two commands, Show linear phase/frequency residual ( r ) and Phase/frequency
traces begin at zero ( z ) , are among the most commonly-used options on the Trace
menu. If you spend much time working with phase- and frequency-difference traces,
their
r and z keyboard shortcuts will quickly become familiar. z can increase visible
detail while preserving the graph’s original shape, while r is better at revealing short-
term noise and other effects that become harder to spot as the graph expands to
Figure 39: Linear trend subtracted from the phase data
Figure 40: Viewing the removed trend without altering the data