HP 54753A User Manual page 215

By defining a reference plane to be at the end of the test fixture (first PCB) and
then normalizing, the errors can be corrected.
Figure 10-5
Normalization uses a short, then a 50 Ω termination to define a reference plane and to generate a
digital filter
Figure 10-6
normalization first defines a reference plane and generates a digital filter. The
normalizing measurement then corrects for the errors introduced by the test
fixture. Notice how the normalized response of the second PCB (DUT) now
matches the response measured earlier of the nearly identical first PCB.
The normalized measurement corrects for the errors introduced by test fixture.
Improving Time Domain Network Measurements
Removing Measurement Errors
10-9