7
Demonstration 5:
Displayed average noise
level (DANL) measurements
and reference trace
subtractions
The DANL floor of the signal analyzer
may adversely affect the phase noise
measurement results, particularly
at the wider offset. The DANL mea-
surement provided by the N9068A/
W9068A measures and references the
X-Series signal analyzer to the carrier
amplitude.
Furthermore, the measured DANL
can be used as a reference trace
when implementing reference trace
subtraction to eliminate the analyzer’s
broadband noise effect from the
phase noise measurements.
Instructions
Keystrokes
On the X-Series Phase Noise mode:
Start DANL measurement and set the
average number to 20. The signal analyzer
averages 20 measurements – wait for
the measurement to finish (the Avg|Hold
counter in the measurement status bar at
the top of the display helps keep track of
the status).
[Mode preset] [Meas] {Log Plot} [Meas
Setup] {Avg Number On} [20] {Enter}, {Meas
Type} {DANL} [Restart]
Save DANL as the reference trace for the
following DANL subtraction
[Trace/Detector] {Select Trace} {Trace 2}
{More 1 of 2} {Copy/Exchange} {From Trace}
{Trace 2} {To Trace} {Trace 3} {Copy Now}
Implement DANL subtraction
[Meas Setup] {More 1 of 2} {Cancellation}
{Cancellation On} {Ref Trace} {Trace 3};
[Meas Setup] {Meas Type} {Phase Noise}
[Single]
Figure 6. DANL measurement result
Figure 7. Phase noise plot with DANL subtraction
