S820E UG PN: 10580-00343 Rev. H 8-9
Vector Voltmeter 8-4 Relative Measurements
8-4 Relative Measurements
Often, absolute phase measurement of a DUT (cable in the following
example) is not as important as the phase relationships among multiple
DUTs. For the following example application, the Vector Voltmeter is used to
make relative phase measurements.
The operations for relative measurements are described in the following
steps.
1. Preset the S820E, then set up for this measurement by setting the
frequency and the measurement type and format.
Measurement format may be LogMag/Phase, LinMag/Phase, SWR, or
Impedance. LogMag/Phase measurement format is used in this
example. You may change the measurement format at any time. If a
reference value has already been recorded in a particular measurement
format, and if you change the measurement format, then the reference
value is automatically converted to the new selected measurement
format.
2. Since many VVM measurements are made relative to a stored
reference, vector error correction is not absolutely required. Absolute
Reflection or Transmission measurements require calibration to
remove residual errors, including port match errors. Refer to
Section 8-6 “VVM Calibration” on page 8-19 for more details.
For A/B or B/A measurements, vector error correction of the instrument
is not possible. In some cases where the measured results are unstable
or not as expected, the overall measurement results may be improved
simply by adding 3 dB or 6 dB attenuators on each measurement port
(A and B). The process of storing the reference value will need to be
repeated if attenuators are added after the initial reference value was
stored.
3. Connect the first DUT (device under test).
4. If you want to use the measurement result of this first DUT as your
reference (the golden DUT), then press the Save Reference submenu
key.
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