Jackson Labs PHASE STATION 53100A, User Manual

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PhaseStation 53100A User’s Manual V1.04 25-Apr-2022 47
Examining changes in stability over time
To make basic “dynamic ADEV”
measurements
6
, refer to the help text
for the
Duration
and
Run Until
fields
in the acquisition dialog, as well as the
Trace History field shown at right.
Specifying a Trace History value
greater than 1 causes TimeLab to
divide the phase record into the given number of regions. Subsequent displays of xDEV
measurements will assign each region its own trace. As the measurement runs, more
recently-acquired regions towards the end of the phase record are drawn in darker
colors, revealing how the stability of a given device changes over time. (If
Trace → Toggle trace thickness ( T ) is enabled, only the most recent region will be
displayed with a heavy trace.)
You can specify a new
Trace History value at any
time after acquisition in
the
Edit → Trace
properties ( e ) dialog. In
the example below, eight
minutes of frequency
readings were taken from
an OCXO shortly after
power-up, and later
rendered with
Trace
History set to 20.
Consequently, each ADEV
trace represents about 24 seconds of phase data. As the oscillator warms up, the later
traces exhibit better stability. Values displayed on the
Sigma(Tau)
chart apply to the
most recent trace.
For more advanced displays of dynamic AVAR/ADEV and related metrics as described in
the literature, consider using the
File → Export phase data to Stable32 ( Ctrl-x ) command
described on page 78 for offline analysis.
6
Galleani, L. , Tavella, P.; Interpretation of the dynamic Allan variance of nonstationary clock data , Frequency Control Symposium, 2007 Joint
with the 21st European Frequency and Time Forum. IEEE International,
pp. 992-997, 2007
Figure 10: Basic stability measurement parameters
Figure 11: Dynamic Allan deviation