R&S FSH
Spectrum Analyzer Mode
Configuring Spectrum Measurements
Operating Manual 1309.6275.12 - 14
105
2.2.7 Using Display Lines
Like markers, display lines help you to determine the level of the signal.
A display line is a straight line that runs horizontally and corresponds to a certain level
value. You can move the display line to each pixel in the display. This means that the
accuracy and exact vertical position of the display line depends on the resolution of the
vertical axis. With a display range of 100 dB, for example, each pixel corresponds to
0.3 dB. In that case, the accuracy of the display line is 0.3 dB. If you enter a value with
a higher resolution, the R&S FSH rounds that value.
You can also move the display line with the rotary knob or the cursor keys. The step
size for movement with the rotary knob is one pixel. The step size for the cursor keys is
10 % of the display range.
M
Press the LINES key.
M
Press the "Display Line" softkey.
The R&S FSH displays the display line as a blue horizontal line. It shows the
vertical position of the line in a table above the diagram area.
When you activate the display line, the R&S FSH also opens an input field to
define the vertical position of the line.
M
Enter the level value you need.
The R&S FSH positions the display line accordingly.
Alternatively you can also move the display line with the rotary knob or the cursor
keys.
2.2.8 Using Limit Lines
Limit lines help you to identify if a signal complies with certain level characteristics.
A limit line is made up out of two or more points that are connected to a line. Each of
the points that define the shape of the limit line consists of two coordinates. One
coordinate defines the horizontal position (e.g. frequency), the other one the vertical
position. With the R&S FSH you can build limit lines that consist of up to 25 points.
Values that define the horizontal characteristics of the limit line can be either absolute
values (e.g. frequency in MHz) or relative values whose reference is the center of the
measurement trace (e.g. the center frequency). Relative values are of advantage if
you, e.g., measure modulated output signals and you change the center frequency but
need the limit line to remain the same. Absolute limit lines have the file extension
".abslim" while relative limit lines have the file extension ".rellim"
Values that define the vertical characteristsics are always level values in dB. If the
scaling of the vertical axis is currently a linear one (units V or W), the R&S FSH
automatically switches to a logarithmic scaling after you turn on the limit line.
