Keysight Technologies N9321C User Manual page 63

Functions and Measurements
Making Distortion Measurements
Notice the Marker' amplitude readout. This is the difference of the
distortion product amplitude between 0 dB and 10 dB input
attenuation settings. If the Markerabsolute amplitude is
approximately 1 dB for an input attenuator change, the analyzer

is generating, at least in part, the distortion.
The Markeramplitude readout comes from two sources:
1) Increased input attenuation causes poorer signal-to-noise ratio.
This causes the Markerto be positive.
2) The reduced contribution of the analyzer circuits to the harmonic
measurement causes the Markerto be negative.
Large Markerreadout indicates significant measurement errors.
Set the input attenuator to minimize the absolute value of Marker.
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