Keysight Technologies C Series - Power Spectral Density (PSD) Function (SA Mode Only)

216 Keysight N9915-90020 User’s Guide
SA (Spectrum Analyzer) Mode (Option 233–Mixed Analyzers)FUTURE
SA Mode Settings
With a Noise Marker present, the Res BW can be changed and the displayed
noise floor will also change, but the Noise Marker readout will remain about
the same.
Noise Markers can be used like regular markers. A Noise Marker is
distinguished from a regular marker by (1Hz) after the marker readout value.
Learn more about regular markers in “All about Markers” on page 734.
How to measure Noise with a marker
1. Press Marker
to create or select a Normal or Delta marker to use to
measure Noise.
2. Then More > Marker Function > Noise ON OFF.
Power Spectral Density (PSD) Function (SA Mode Only)
The Power Spectral Density Function (PSD Function) is a way to normalize the
SA measurement to a 1 Hz Bandwidth. Every SA Resolution Bandwidth is
characterized by an “Equivalent Noise Bandwidth” (ENBW) that in general is a
few percent wider than the Resolution Bandwidth itself. To normalize the
measurement to this ENBW, an offset is added in this amount:
PsdOffset = -10 * Log10( ENBW )
This offset is added to the Reference Level, the Trace values, and Marker
values and suffix annotation is updated with “/Hz” or “(1Hz)” as an indication
that the results are now normalized to 1Hz. This is similar to what the Noise
Marker function does, but the Noise Marker also first averages several trace
points around the marker location. Similar to a Noise Marker, the PSD Function
will also auto-couple the Detector to RMS.
See also,
“Noise Marker” on page 215.
How to measure the PSD function:
—Press Scale/Type
> More > PSD Function ON OFF (Default == OFF).