S820E UG PN: 10580-00343 Rev. H 8-19
Vector Voltmeter 8-6 VVM Calibration
8-6 VVM Calibration
VVM Calibration versus Save Reference
Which one should be used?
The Save Reference function stores the current measurement and normalizes
the main measurement display to the stored value. All subsequent
measurements are now displayed as relative to the stored reference value.
This function is independent of VVM Calibration and should not be confused
with VVM Calibration. The Save Reference function will be used for ALL
relative measurements made with the VVM. In comparison, VVM Calibration
may not be required for all VVM relative measurements, although it is
recommended because it allows for absolute measurement values of the
DUTs, including the reference DUT, and it removes any inherent system
errors of the instrument itself. VVM Calibration also compensates (via vector
error correction) for any test cables, adapters, or fixtures that may have been
added between the DUT and the instrument and the appropriate calibration
kit.
Absolute VVM Measurements
Absolute, error corrected reflection or transmission measurements may be
made on a DUT in VVM mode. For absolute measurements, a VVM
calibration is required. The absolute measurement may then be stored as a
reference, if required. Vector error corrected measurements on additional
DUTs relative to the stored reference can then be made. This provides the
best possible accuracy for relative VVM reflection and transmission
measurements. VVM calibration removes system errors and defines a known
measurement reference plane, which is mandatory for making accurate
absolute measurements.
Relative VVM Measurements
Many VVM measurements are made relative to a stored reference, and in
these cases, vector error correction may not be required. VVM calibration
removes system errors and may improve relative measurement results. For
these reasons, when you are making relative measurements, VVM calibration
is recommended, but it is not mandatory.
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