Averaging Options - National Instruments NI Spectral Measurements Toolkit User Manual

Averaging Options

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