R&S ZNB Series User Manual page 362

®
R&S ZNB/ZNBT
Smoothing
Activates the smoothing function for the active trace, which can be a data or a memory
trace.
With smoothing active, the trace value at each sweep point is replaced by the arith-
metic mean of the trace values at the sweep point itself, and at neighboring sweep
points (symmetrically, to the left and to the right). The number of trace values to be
averaged is defined by the
the trace.
Smoothing operates on the formatted trace and does not significantly increase the
measurement time.
Tip: The sweep average is an alternative method of compensating for random effects
on the trace by averaging consecutive traces. Compared to smoothing, the sweep
average requires a longer measurement time but does not have the drawback of aver-
aging out quick variations of the measured values.
See
Remote command:
CALCulate<Chn>:SMOothing[:STATe]
Aperture
Defines how many trace values are averaged to smooth the trace if
switched on.
An "Aperture" of a % means that the value at sweep point n
the arithmetic mean of the values at sweep points
max { 1,
where N is the number of points of the sweep (or sweep segment for segmented
sweeps).
1
n – a/100·N/2
The range definition above takes boder cases and rounding into account.
Tips: Finding the appropriate aperture
A large smoothing aperture enhances the smoothing effect but can hide quick varia-
tions of the measured values and thus produce misleading results.
To avoid errors, observe the following recommendations.
●
Start with a small aperture and increase it only as long as you are certain that the
trace is still correctly reproduced.
●
Select a smoothing aperture that is small compared to the width of the observed
structures (e.g. the resonance peaks of a filter). If necessary, restrict the sweep
range or switch smoothing off to analyze narrow structures.
User Manual 1173.9163.02 ─ 62
Chapter 5.9.3, "Average
⌈ n – a/100·N/2 ⌉ }, ..., min { N, ⌊ n + a/100·N/2 ⌋ },
Smoothing interval
Length: a/100·N
Midpoint
n
Sweep points inside the smoothing interval
Aperture and can be adjusted according to the properties of
tab", on page 421.
GUI reference
Trace Config softtool
Smoothing
∈ {1, ..., N} is replaced by
n + a/100·N/2
is
N
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