Matlab envelope function

1. What is envelope function in Matlab?
2. How to use envelope detector in Matlab?
3. What is the functionality of the envelope detector?
4. How do you find the envelope of a signal?

What is envelope function in Matlab?

[ yupper,ylower ] = envelope( x ) returns the upper and lower envelopes of the input sequence, x , as the magnitude of its analytic signal. The analytic signal of x is found using the discrete Fourier transform as implemented in hilbert .

How to use envelope detector in Matlab?

You find the envelope of the signal by taking the absolute value of the analytic signal. The envelope is a low frequency signal compared to the original signal. To reduce its sampling frequency, to eliminate ringing and to smooth the envelope, you downsample this signal and pass the result through a lowpass filter.

What is the functionality of the envelope detector?

An envelope detector can be used to demodulate a previously modulated signal by removing all high frequency components of the signal. The capacitor and resistor form a low-pass filter to filter out the carrier frequency.

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.