Jackson Labs PHASE STATION 53100A, Руководство пользователя

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PhaseStation 53100A User’s Manual V1.04 25-Apr-2022 58
Examining traces in detail
In the example below, a crystal oscillator was measured over a 12-hour period. The
Measurement → Phase difference ( p ) and Measurement → Frequency difference ( f )
views appear side-by-side for comparison.
Not much detail is visible in either trace. Some sporadic frequency jumps are present,
but they’re not easily examined since their height is such a small fraction of the plot’s
overall magnitude.
Subtract global linear phase trend (frequency offset) ( Ctrl-o )
command expands the phase-difference trace somewhat by removing its linear trend,
but it only moves the frequency-difference trace down a bit:
In fact, we could have achieved a similar effect without altering the phase record by
viewing the phase-difference trace with
Trace → Show linear phase/frequency residual
( r ), or by viewing the frequency-difference trace with Trace → Phase/frequency traces
begin at zero ( z ) .
10
10
The
Trace → Phase/frequency traces begin at zero (
z
)
option can actually be more useful – not only can it be toggled on and off without
altering the phase data, but it also forces the beginning of the frequency-difference trace to midscale. See page 66.
Figure 20: Two views of the same phase data record
Figure 21: Subtracting the linear phase trend