Chapter 2 103
Performance Verification Tests
13. Input Attenuation Switching Uncertainty
4. For each attenuation error value in Column 4 of Table 2-19, calculate
the attenuation errors by subtracting the difference between the
Table 2-18 Total Actual Attenuation and Total Nominal Attenuation
from the difference between the Total Actual Attenuation and Total
Nominal Attenuation at 55 dB. Note that the total nominal
attenuations listed in Table 2-19 are in a different order than those
listed in Table 2-18.
AttenErr = (ActAtten(55 dB) - 55 dB) - (ActAtten(X dB) -
NomAtten(X dB))
Where:
Example of attenuation error calculation for 35 dB nominal
attenuation:
Setup for Switching Uncertainty Measurement
5. Connect the equipment as indicated in Figure 2-13. The 6 dB fixed
attenuator (or minimum loss pad for 75 Ω input analyzers) should be
connected directly to the input connector of the analyzer.
6. Press Preset on the analyzer. Press the Factory Preset softkey, if it is
displayed. Press System, Alignments, Auto Align, Off. Set the controls
as follows:
FREQUENCY, 50 MHz
SPAN, 100 kHz
AMPLITUDE, –55 dBm (50 Ω Input only)
AMPLITUDE, –6.2 dBmV (75 Ω Input only)
AMPLITUDE, Attenuation, 10 dB
AMPLITUDE, Scale/Div, 2 dB
BW/Avg, 30 kHz
BW/Avg, Video BW, 100 Hz