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Demonstration 2:
Log plot measurement
The log plot is the most-frequently
used presentation of a DUT's phase
noise performance. It measures
single-sideband phase noise (in dBc/
Hz) versus offset frequencies from the
carrier on a logarithmic scale.
View the entire phase noise behavior
across decades of offset frequencies.
Adjust the number of decades by
selecting the appropriate start and
stop offsets.
Perform trace smoothing with the
user-adjustable smoothing segment
length and view it superimposed with
the raw data trace.
Instructions
On the X-Series in Phase Noise mode:
View log plot
Set the signal analyzer with a carrier fre-
quency of 1 GHz and an amplitude reference
level of 0 dBm
Set the start offset to 100 Hz and stop
offset to 100 MHz and restart the log plot
measurement
Turn the Decade table on, so that you can
have both graphic and tabular presentations
Figure 3. Log plot phase noise with a smoothed trace and decade table turned on
4
Keystrokes
[Meas] {Log Plot}
[FREQ Channel] {Carrie Freq} [1]
{GHz}; [AMPTD Y Scale] {Ref Value}
[0] {dBm}
[SPAN X Scale] {Start Offset} [100]
{Hz}; {Stop Offset} [100] {MHz}, then
[Restart]
[Meas Setup] {More 1 of 2},
{Decade Table on}
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