Jackson Labs PHASE STATION 53100A, User Manual, Page: 88 / 225

PhaseStation 53100A User’s Manual V1.04 25-Apr-2022 88
automatically be removed from both of the phase records. See page 136 for more
information on cross ADEV measurements.
Subtract global linear phase trend (frequency offset) ( Ctrl-o )
Subtract global linear frequency trend (drift line) ( Ctrl-l )
Subtract quadratic linear frequency trend (drift curve) ( Ctrl-q )
These related commands are used to remove global offsets and trends from the
selected plot’s phase record. This is typically done to improve visibility of local trends
and features whose magnitude is small compared to the Y-axis range. For detailed
usage information and examples, as well as some alternative viewing methods that
don’t alter the phase record contents, see page 58.
Two commands on the Trace menu, Phase/frequency traces begin at zero (z) and Show
linear phase/frequency residual ( r ) , provide non-destructive functionality similar to the
Edit → Subtract global linear phase trend (frequency offset) ( Ctrl-o ) command. See
page 91 for more information.
If the selected plot has any background tasks in progress when any of these commands
are issued, an error message will be displayed. Background tasks are those in which the
plot’s memory-resident phase record is being accessed by a background thread during
initial acquisition, when reloading a saved .TIM file, and when reconstructing the xDEV
statistical traces after a previous modification to the phase record.
Note that subtracting trends from data records that exhibit a large amount of variance relative
to their overall slope – such as might be obtained from comparisons of GPSDO or atomic
standards -- can result in numerically unstable outcomes that vary randomly based on the
number of points in the data record. You may wish to toggle the subtraction operation with
Edit →Undo last flatten or subtract operation ( Ctrl-z ) to verify that the command performed as
expected.