ENVEXTRACT - Extract envelope of input signalUsage:
Description:ENVEXTRACT(insig,fs,cutoff) extract the envelope of an input signal insig sampled with a sampling frequency of fs Hz. The envelope extraction is performed by half-wave rectification followed by low pass filtering to a a cutoff frequency specified by the parameter cutofffreq.
ENVEXTRACT(insig,fs) does the same assuming a cutoff frequency of 1000 Hz.
This method is described in XXX