Measurement Basics
R&S
®
FSW-K40
32
User Manual 1173.9286.02 ─ 15
The application supports the definition of up to five ranges, each with a different slope.
The ranges themselves are defined by corner frequencies. Corner frequencies are
those frequencies that mark the boundaries of typical curve slopes. If you use all five
ranges, the result would be a limit line with six segments.
All segments have a slope of 10
dB per decade (f
-1
) by default.
In most cases, these special limit lines will suffice for phase noise measurements as
they represent the typical shape of a phase noise curve.
Figure 4-8: Typical looks of a special limit line
Normal limit lines
Normal limit lines on the other hand may have any shape and may consist of up to 200
data points. You can turn on up to 8 normal limit lines at the same time. Each of those
limit line can test one or several traces.
If you want to use them for phase noise measurements however, a limit line must be
scaled in the unit dBc/Hz and must be defined on a logarithmic scale on the horizontal
axis.
Using Limit Lines
