Gain Measurement Uncertainty; Test Description - Keysight NFA Series Performance Verification And Calibration Manual

Test Descriptions

Gain Measurement Uncertainty

Gain Measurement Uncertainty
NOTE You must perform the Noise Figure Range and Accuracy performance
test (see page 55) before this test.

Test Description

The NFA uses internal IF attenuator values for measuring gain. The test
comprises of an internal IF attenuator calibration. Using an external
50 MHz CW signal at -46dBm the attenuator values are computed as
error ratios.
The analyzer only uses a range of 40dB for any given measurement from
-20dB to >+40dB within the available 0 - 70dB IF attenuator range.
Therefore, the actual Instrumentation Uncertainty is calculated as the
maximum peak to peak error over any 40dB range within the available
0 - 70dB IF attenuator range. The 30 available ranges are all tested for
the maximum and minimum Peak to Peak values within their respective
40dB range. The 30 peak to peak values are then compared and the
worst case error is reported as the Instrumentation Uncertainty error.
The graph below shows a typical plot of the data. 1 of the 30 available
ranges is shown giving the typical Instrumentation Uncertainty for the
specific range between 30 to 70dB.
64 Chapter 2