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Basic Measurements
Making Measurements
Instrument Nonlinear Correction
Instrument Nonlinear Correction (INC) is a digital pre-distortion (DPD) based
correction using a Keysight signal analyzer (N9042B, N9040B, or N9030B) to
compensate for nonlinearities in the VXG. INC is useful in reducing EVM (and
other metrics impacted distortion) at high power levels and extending the
range of the power with linear output of the VXG. INC is a point correction valid
for a given frequency/power/waveform combination and can be used for EVM
and ACP measurements at high power levels (>5 dB). The VXG must have the
N7653APPC PathWave automatic channel response correction and
S-parameter de-embedding license installed.
Instrument nonlinear corrections compensate for nonlinearities in the VXG.
Improvement to EVM will only be seen at power levels where distortion is the
limiting factor. INC will not improve EVM in the area where signal to noise ratio
(SNR) is the limiting factor.
Setting Up an INC 1CC 4 GHz, 10 dBm EVM Measurement
On the VXG:
In order to compare before and after correction results, we will start by making
an EVM measurement without applying corrections.
1. Select Preset > Preset to set the instrument to a know state.
2. In the Output area, set Frequency to 4 GHz and Power to
10 dBm.
3. Select the Signal block to open the Vector Modulation Signal Setup panel.
M9484C Measurement Guide
67
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