Receiver Mode
R&S
®
ESR
155
User Manual 1175.7068.02 ─ 12
Adjusting the reference level and level range
Changing the reference level and level range also affects the color scheme in the
spectrogram.
Make sure, however, that you never adjust in a way that could overload the R&S
ESR.
Defining the shape of the color curve
Now that the color scheme and range of the color map suit your needs, you can
improve the color map even more by changing the shape of the color curve.
The color curve is a tool to shift the focus of the color distribution on the color map. By
default, the color curve is linear. The color curve is linear, i.e. the colors on the color
map are distributed evenly. If you shift the curve to the left or right, the distribution
becomes non-linear. The slope of the color curve increases or decreases. One end of
the color palette then covers a large amount results while the the other end distributes
a lot of colors on relatively small result range.
You can use this feature to put the focus on a particular region in the diagram and to be
able to detect small variations of the signal.
Example:
Figure 5-3: Linear color curve shape = 0
The color map above is based on a linear color curve. Colors are distributed evenly
over the complete result range.
Figure 5-4: Non-linear color curve shape = -0.5
After shifting the color curve to the left (negative value), more colors cover the range
from -105.5 dBm to -60 dBm (blue, green and yellow). In the color map based on the
linear color curve, the same range is covered by blue and a few shades of green only.
The range from -60 dBm to -20 dBm on the other hand is dominated by various shades
of red, but no other colors. In the linear color map, the same range is covered by red,
yellow and a few shades of green.
The result of shifting the color curve is that results in a particular result range (power
levels in case of the spectrogram and densities in the case of the spectral histogram)
become more differentiated.
You can adjust the color curve by moving the middle slider in the color curve pane to a
place you want it to be. Moving the slider to the left shifts the focus in the direction of
low values. Most of the colors in the color map are then concentrated on the low power
levels (spectrogram) or densities (histogram), while only a few colors cover the upper
end of the color map or high power levels or densities. Moving the slider to the right
shifts the focus to the higher amplitudes or densities.
Measurements and Result Displays
