NI Spectral Measurements Toolkit User Guide
26
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Averaging Options
Figure 10 illustrates the options available for spectrum averaging.
Figure 10.
Spectrum Averaging Options
The averaging processes apply weighting to the < > operator in both RMS
and vector averaging as shown in the following equation:
Y
k
= <
X
>
k
=
a
1
×
Y
k
– 1
+
a
2
×
X
k
where
Y
k
is the new average,
Y
k
– 1
is the previous average, and
X
k
is the new
measurement.
For linear weighting,
a
1
= (
k
– 1)/
k
, and
a
2
= 1/
k
For exponential weighting,
a
1
= (
k
– 1)/
k
and
a
2
= 1/
N
for
k
≤
N
,
a
1
= (
N
– 1)/
N
and
a
2
= 1/
N
for
k
>
N
where
N
is a user-specified constant that determines how much weight
is given to recent data relative to older data. Small values of
N
place more
Exponential
Average Size
Peak-Hold
No Averaging
Vector
RMS
Averaging
Type
Linear
Weighting
Type
Linear
Weighting
Mode
Moving Average
Auto Restart
Continuous
One Shot
