Measurements and results
R&S
®
FSVA3000/ R&S
®
FSV3000
331
User Manual 1178.8520.02 ─ 08
Required sweep time in FFT mode
In FFT mode, the sweep time is divided among the required subspans. To ensure the
required dwell time at each frequency, the sweep time must be at least:
<sweep time>
min
= <required_dwell_time> * <number_of_FFT_subspans>
To ensure that the signal within a single subspan is always captured without a gap, the
maximum sweep time is restricted.
The number of FFT subspans is indicated in the "Sweep" settings, see
on page 476. It is also returned for the
query.
5.13.3.3
Frequency resolution - sweep points and scaling
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, 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 can 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"). If possible
for the selected RBW and span, the minimum required number of sweep points to fulfill
this condition is indicated. If the number of sweep points exceeds the limit, reduce the
span or increase the RBW.
The R&S
FSV/A supports a maximum of 200001 sweep points for EMI measurements.
Electromagnetic interference (EMI) measurement
