Return Loss Measurements - Keysight N9912A User Manual

Interference Rejection
Use this setting when you suspect that other signals in the area are interfering with a
measurement. Interference may look like a spike or lack of stability in the
measurement trace. While monitoring a measurement at a specific frequency, toggle
this setting between ON and OFF. If the measurement result decreases while ON,
then there is an interfering signal in the area. Continue to make measurements with
Interference Rejection ON. However, this will slow the measurement speed.
Once enabled, up to SIX sweeps may be required before the interfering signal is
neutralized.
This setting can be changed at any time without affecting calibration accuracy.
How to set Interference Rejection
 Press Meas Setup 4.
 Then
 Then choose from the following:
Coupled Frequency
This setting, especially useful for a Return Loss & DTF measurement, allows both
measurements to have different frequency ranges.
How to set Coupled Frequency
With a Return Loss & DTF measurement present:
 Press Meas Setup 4
 Select the DTF measurement (Tr2) using the ▲|▼ arrows.
 Then choose from the following:



Return Loss Measurements

Return loss can be thought of as the absolute value of the reflected power as
compared to the incident power.
When measuring an OPEN or SHORT, all incident power is reflected and
approximately 0 dB return loss is displayed.
26
Interference Rejection [current
No interference rejection and fastest possible sweep speed.
Off
o
The lowest level of Interference rejection.
Minimum
o
The medium level of Interference rejection.
Medium
o
The highest level of Interference rejection.
Maximum
o
- Both the Return Loss and DTF traces have the same
Coupled Freq ON
frequency range settings.
(default setting) - Both traces are allowed to have individual
Coupled Freq OFF
frequency range settings. When set to OFF:
The Return Loss measurement frequency settings are made in the usual manner.
o
Learn how on page 22. When a new Start or Stop frequency is selected,
Coupled Frequency is automatically set to OFF.
The DTF measurement is made using the frequencies as determined by the DTF
o
Frequency Mode setting. Learn more on page 32.
setting].
FieldFox User's Guide