X90 mobile modules
X90 mobile system User's manual V 1.20 - Translation of the original manual
251
Envelope analysis
Normally in an envelope analysis, the frequency spectrum of the envelope signal is evaluated. Suppressing the
steady component gives a frequency spectrum that exhibits only one increased amplitude at the frequency of the
low-frequency sinusoidal oscillation.
The envelope signal of the periodically peaked excited machine resonance shows mostly increased amplitudes in
the shock pulse repetition rate and its multiples.
The envelope analysis is thus a method for differentiating between harmonic causes (imbalance, orientation) and
impact-related causes (roller bearing damage, gearing damage, etc.).
Conversely, it must be stated that harmonic causes in an envelope spectrum cannot be determined accordingly.
Amplitude
[mg]
Time [s]
Figure 84: Time signal with envelope
Amplitude
[mg]
Frequency [Hz]
Figure 85: Resulting frequency spectrum of the envelope
