Jackson Labs PHASE STATION 53100A, Руководство пользователя

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PhaseStation 53100A User’s Manual V1.04 25-Apr-2022 53
Hints for xDEV measurements
•
The 53100A does not display its own measurement floor in the ADEV, MDEV, HDEV,
TDEV, or MTIE views. Instead, you can (and should) make residual plots for
measurements that may approach the instrument floor, using similar frequencies
and signal levels. These residual plots can be saved, loaded and shown with
Display → Overlay all loaded plots ( o ) next to your actual measurement traces.
•
There’s a direct relationship between measurement bandwidth and the instrument
noise floor in ADEV and other phase/frequency measurements . You may find it
helpful to observe drift-prone sources or oscillator startup characteristics at 5 kHz or
50 kHz ENBW, but be aware that the stability noise floor will be somewhat higher.
Again, a separate residual plot at the frequencies and signal levels of concern can
tell you exactly where the limits are.
• The measurement bandwidth also influences the size of the phase record that must
be allocated before a measurement of a given duration can begin. As a result, you
may experience out-of-memory errors if you tell TimeLab to record several hours'
worth of phase data at 500 Hz ENBW/1K points per second. Increasing the
Output
decimation value in the Additional Options dialog is a great way to reduce
acquisition memory requirements, but it will not improve the xDEV noise floor. The
only way to lower the xDEV floor is to select a narrower measurement bandwidth.
•
Fewer samples are available to contribute to bins near the right end of an xDEV
trace. As a result, measurement confidence decreases at longer tau intervals. To
increase the minimum number of samples that must contribute to a given xDEV bin
in order for that bin to be displayed, you can change the
Bin Threshold parameter in
the acquisition dialog, or use Edit → Trace properties ( e ) to specify a new value for
the same field at any time after acquisition.
However, because TimeLab employs overlapped xDEV algorithms, small changes to
Bin
Threshold
may have no effect. Once the phase record grows long enough to provide
data at a given tau interval, each additional sample adds another data point to the
corresponding xDEV bin. If this is an issue, try setting the
Bin Threshold to a large
fraction of the total phase record size. The idea is to force TimeLab to render the xDEV
trace as if much less data were available.