Chapter 2 299
Performance Verification Tests
35. Displayed Average Noise Level: Agilent E4401B and E4411B
35. Displayed Average Noise Level:
Agilent E4401B and E4411B
This performance test measures the Displayed Average Noise Level
(DANL) within the frequency range specified. The analyzer input is
terminated in its characteristic impedance. If the analyzer is also
equipped with a tracking generator (Option 1DN or 1DQ), the tracking
generator is also terminated in its characteristic impedance and set for
maximum leveled output power.
The test tunes the analyzer frequency across the band and uses the
marker to locate the frequency with the highest response. It then reads
the average noise in zero span using the minimum resolution
bandwidth (RBW) specified for the analyzer. Analyzers having Option
1DN (Tracking Generator) installed are tested in a 1 kHz RBW.
Analyzers having Option 1DR (Narrow Bandwidths) installed have a
minimum RBW of either 100 Hz or 10 Hz. Even though analyzers
having Option 1D5 (High Stability Frequency Reference) and firmware
revision A.08.00 or later installed have a minimum RBW of 1 Hz, DANL
for these analyzers is specified and tested with a 10 Hz RBW.
To reduce measurement uncertainty due to input attenuator switching
and resolution bandwidth switching, a reference level offset is added.
The 50 MHz alignment signal is used as the amplitude reference for
determining the amount of offset required. The offset is removed at the
end of the test by pressing instrument preset.
The related adjustment for this procedure is “Frequency Response.”
Equipment Required
Termination, 50 Ω, Type-N (m) (2 required for Options 1DN or 1DQ)
Additional Equipment for 75 Ω Input
Termination, 75 Ω, Type-N (m) (2 required for Option 1DQ)
Adapter, Type-N (f), to BNC (m), 75 Ω
Procedure
CAUTION Use only 75 Ω cables, connectors, or adapters on instruments with 75 Ω
connectors, or damage to the connectors will occur.
1. Set up the analyzers as shown in Figure 2-53.