Common Measurement Settings
R&S
®
FSW
406
User Manual 1173.9411.02 ─ 19
On the other hand, the narrower the partial span, the more steps are required to cover
the entire span, thus increasing analysis and calculation time. To
optimize the sweep
rate
, the widest possible partial span (depending on the RBW) is used.
For an optimal sweep rate, it is recommended that you set the sweep time to "Auto", as
well.
For general purpose measurements, an "Auto" mode is available, which provides a
compromise between a large dynamic range and a fast sweep
. In this case, a
medium-sized partial span is used.
FFT mode and external mixers (R&S
FSW-B21)
The partial span optimation modes "Dynamic" and "Auto" include automatic suppres-
sion of unwanted mixing products. Thus, when using external mixers (R&S
FSW-B21),
use the "Speed" mode to obtain similar results in FFT mode as in normal sweep mode.
FFT mode and EMI measurements (R&S
FSW-K54)
For EMI measurements (using R&S
FSW-K54), the partial span optimation mode
"Dynamic" is not supported. "Auto" mode always uses "Speed" optimization.
Optimization for zero span sweeps
For normal sweeps in the time domain (zero span), the optimization mode determines
the selection of the A/D converter prefilter, which depends on the RBW.
In
"Dynamic" mode
, the narrowest possible prefilter is used.
In
"Speed" mode
, the widest possible prefilter is used.
In
"Auto" mode
, a medium-sized prefilter is used.
6.5.1.6
Which Data May Pass: Filter Types
While the filter is irrelevant when measuring individual narrowband signals (as long as
the signal remains within the RBW), the measurement result for broadband signals is
very dependant on the selected filter type and its shape. If the filter is too narrow, the
signal is distorted by the filter. If the filter is too wide, multiple signals can no longer be
distinguished. Generally, the smaller the filter width and the steeper its edges, the lon-
ger the settling time and thus the longer the sweep time must be.
All resolution bandwidths are realized with digital filters. Normal (3dB) Gaussian filters
are set by default. Some communication standards require different filters.
For a list of available filter types, see
chapter 6.5.3, "Reference: List of Available RRC
Bandwidth, Filter and Sweep Configuration
