Keysight N9927-90001 User’s Guide 493
VVM (Vector Voltmeter) Mode - Option 308
1-Port Cable Trimming Measurements
1-Port Cable Trimming Measurements
A 1-Port Cable Trimming measurement is used in a cable fabrication procedure
to validate proper electrical length.
How to make a 1-Port Cable Trimming Measurement
1. Press Mode then VVM then 1-Port Cable Trimming.
2. Press Freq/Dist
then enter the frequency for the measurement.
3. To improve measurement stability, change the IF Bandwidth, Output
Power, and Averaging settings as needed.
4. 4.Press Meas Setup 4
then Zero OFF.
5. Optionally calibrate the FieldFox. Learn more about VVM calibration in
“VVM Calibration” on page 491.
6. To ensure that the calibration is adequate, perform the following optional
Measurement Verification procedure.
a. Connect a short standard to PORT 1 where cables to be trimmed
will be connected.
b. Press Meas Setup 4
and press Zero.
c. Remove the short standard and connect the open standard.
d. Confirm that magnitude measurement is less than –0.1 dB and that
the phase value reads 180° degrees.
7. Attach the shortest cable to the FieldFox PORT 1 connector. This cable is
the reference cable. Leave the end of the reference cable open
(unterminated).
8. Press Meas Setup 4
then press Zero.
— The R receiver measures incident
signal (green line) out of the source.
— The A receiver measures reflected
signal (red line) from the end of the
DUT (black line).
— In VVM mode, the display ALWAYS
shows ratioed (A/R) measurements
which is the electrical length of the
DUT.
This measurement verification procedure is suitable for low frequency
measurements. However, for high frequency measurements, a more
sophisticated procedure is required.
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