National Instruments NI Spectral Measurements Toolkit - Manual (Page 26)

NI Spectral Measurements Toolkit User Guide 26 ni.com
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