Howtosignalprocessing
How do you find the envelope of a signal?
In the EMD algorithm, the upper and lower envelopes of signals are obtained by using two steps: 1) identify all the local extrema; 2) interpolate between extrema by a cubic spline [9]. The interpolative envelope includes the upper and lower envelopes.
What is envelope of a signal?
In physics and engineering, the envelope of an oscillating signal is a smooth curve outlining its extremes. The envelope thus generalizes the concept of a constant amplitude into an instantaneous amplitude. The figure illustrates a modulated sine wave varying between an upper envelope and a lower envelope.
