Marker Measurements > Using Markers > Noise Markers
in the Spectrum Display
Using Noise Markers in the Spectrum Display
Using Noise Markers in the Spectrum Display
In the Spectrum display, you can set Markers to Noise Mode to measure noise on the trace. Markers in
Noise Mode operate just as they do in normal mode, but the readouts for the markers are in dBm/Hz
and dBc/Hz.
dBm/Hz is the power in milliwatts referenced to a 1 Hz bandwidth. To make this measurement, the
analyzer assumes that the measured signal is random noise. It then converts the measured power (made at
any RBW) to the power that would be measured had a 1 Hz
fi
lter been applied for the measurement.
dBc/Hz represents dBm/Hz referenced to a carrier. Here, it is assumed that the carrier is a CW signal,
and its signal level does not change when the RBW is changed, so the Reference Marker measurement
on the carrier is unchanged from any other marker measurement. However, the delta marker values
are converted to dBm/Hz, and then a difference value, in dBc/Hz, is calculated between each delta
measurement and the reference.
Measuring Noise
To measure noise on a Spectrum trace:
1.
Select
Markers
>
De
fi
ne
to display the Markers control panel.
2.
Click
Add
. The
fi
rst marker de
fi
ned is always designated the Marker Reference. Subsequently de
fi
ned
markers are designated as Delta Markers (you can also select and adjust markers by clicking on an
existing marker in the display).
3.
Click
Add
again so that there are at least two markers de
fi
ned.
4.
Check that
Readouts
is set to Delta.
5.
If you have more than one trace de
fi
ned, use the drop-down list for each marker to set it to the trace
on which you want to measure noise.
6.
Select the
Settings
button to display the Spectrum settings control panel.
7.
Click the
Prefs
tab.
8.
Click the
Marker Noise Mode
check box so it is checked.
9.
Click the
Traces
tab.
10.
Verify that Detection is set to
Average
for the trace you are using for this measurement.
11.
Click the
Ana
(Analysis) button.
12.
Select the
Units
tab.
13.
Select
dBm
for the Amplitude units.
14.
Click the Close button to remove the control panel.
RSA6100A Series Real-Time Spectrum Analyzers Help
289
Summary of Contents for RSA6100A Series
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