Spectrum Measurements
R&S
®
ESR
298
User Manual 1175.7068.02 ─ 12
Setting the Number of Sweep Points
The number of sweep points defines the number of measurement values collected dur-
ing one sweep. Thus, increasing the sweep points also increases the accuracy of the
results regarding the frequency resolution.
Because EMI measurements often cover a large frequency range you should define an
adequate number of sweep points, especially when performing the measurement on a
logarithmic axis. Like 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 final evaluation of
narrowband interferers.
Example:
Linear axis:
In case of a linear axis, the distance between the sweep points is equal, e.g. 200
kHz.
Logarithmic axis:
In case of 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 distance is several MHz.
The R&S
ESR supports a maximum of 200000 sweep points. 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 when doing the final evaluation. Even when
covering 30
MHz to 1
GHz with logarithmic scaling and 120
kHz RBW.
Controlling V-Networks
For more information on Line Impedance Stability Networks see
Measurements
