-
An 'Enveloping
Spectrum' plot is identical to a conventional spectrum in the way it displays
data: amplitude vs. frequency.
-
However, there
is a significant difference in the way the raw data is processed.
-
Whereas conventional
FFT processing extracts simple sinusoids from complex motion, enveloping
spectrum signal processing looks for transient (instantaneous) impacts
- the "striking" action discussed earlier versus the "pushing" action the
FFT works well with.
-
These impacts
do not usually survive the conventional FFT process and therefore are kept
hidden from the analyst.
-
However, knowledge
of the frequency of these impacts provides extremely important information
towards proper diagnosis of machinery problems at an earlier stage than
would be possible with conventional FFT analysis.
-
This additional
analysis tool is particularly useful in diagnosing bearing faults.
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