R&S FSH
Spectrum Analyzer Mode
Performing Spectrum Measurements
Operating Manual 1173.6275.12 - 30
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The following examples are based on the green-yellow color scheme.
► Select the color scheme you are most comfortable with.
The R&S FSH adjusts the screen colors according to your selection.
It is possible that the color distribution is not ideal in the current configuration. You
have two ways to set things straight.
By cutting the reference level, you can eliminate amplitudes from the color map
that are not part of the signal.
Example: By default, the spectrogram reference level is 30 dBm.
That means that signal parts with
an amplitude of 30 dBm would be
yellow in the spectrogram, and
signal parts with a very small
amplitude would be dark green.
Everything in between is a shade
of the colors between. As the
colors are distributed over a very
large range (about a 150 dBm or
more), it is likely that you can not
distinguish details in the signal you
have measured.
Therefore you should adjust the color map to the overall shape of the signal you
are measuring. Let's say, for example, that the signal has an amplitude range of
about 30 dB with the maximum amplitude at about -60 dBm and the minimum
amplitude at about -100 dBm and the Green-Yellow color scheme. With the default
settings, the spectrogram is made up exclusively of green colors and it's not easy
to distinguish amplitude levels. That's because the yellow color shades are
completely out of range.
To get a better result, change the spectrogram reference level to a level near the
maximum power level that has been measured first.
► Press the "Spectrogram Settings" softkey.
► Select the "Spectrogram Reference Level" menu item.
The R&S FSH opens an input field to enter the spectrogram reference level.
The reference level should be near the maximum level that has been measured
while the spectrogram was running. In the example, the reference level should be
at about -60 dBm.
► Enter the reference level you need.
The R&S FSH now shifts the reference level of the spectrogram to the value you
have entered.
Note that the spectrogram reference level does not affect the spectrum result
display, as well as the spectrum reference level ("Amplitude" menu) does not affect
the spectrogram. In the screenshot the spectrum trace is therefore exactly the
same as in the previous picture.
