The Spectrum Application (RF Measurements)
R&S
®
FPL1000
258
User Manual 1178.3370.02 ─ 11
Because EMI measurements often cover a large frequency range, be sure to define an
adequate number of sweep points, especially when performing the measurement on a
logarithmic axis. As on a linear axis, the distance from one sweep point to the next is
calculated graphically on a logarithmic axis, and is not based on the frequency itself.
Thus, the frequency resolution between two sweep points deteriorates with higher fre-
quencies.
The resolution bandwidth should cover at least one sweep point (more is better). If this
condition is not met, signals or interferences could be missed during refined measure-
ment of narrowband interferers. If the distance between two sweep points is larger than
RBW/3, a warning is displayed in the status bar ("Increase Sweep Points").
Example:
Linear axis:
With a linear axis, the distance between the sweep points is equal, e.g. 200
kHz.
Logarithmic axis:
With a logarithmic axis, the distance between sweep points is variable. In the spectrum
from 10
Hz to 100
Hz, the distance is a few Hz. Between 100
MHz and 1
GHz, the dis-
tance is several MHz.
The R&S
FPL1000 supports a maximum of 200001 sweep points for EMI measure-
ments.
This number is based on typical bands measured with a single resolution bandwidth.
There are sufficient sweep points to make sure that a signal is found during the refined
measurement, even when covering 30
MHz to 1
GHz with logarithmic scaling and
120
kHz RBW.
Controlling V-Networks (LISN)
For measurements on power lines, EMI measurement adds functionality to the
R&S
FPL1 to control a line impedance stabilization network (LISN) directly. Thus you
can determine the interference caused by power supplies and cables.
This feature requires the optional additional interfaces (R&S
FPL1-B5).
Measurements and Results
