Envelope Detction for Signal Analysis

Computes the envelope of the signal by two methods: 1.LPF method 2.Hilbert Transform

y=envelope(Signal,Fs) computes the Envelope of the input Signal with a Sampling Frequency 'Fs' and gives the envelope signal by Hilbert transform method as the output y.
The function computes the envelope of the signal by two different methods.

First Method: By Using Low Pass Filter. The Signal is Squared, passed
through LPF and then taken square root.
Second Method: Using Hilbert Transform. Hilbert Transform is taken using the inbuilt function in Matlab

The Function Displays the FFT of the original signal and also the FFT of
the envelope signal by both the methods

The function basically is for computing Envelope Signal for Condition Monitoring of rotating equipments by vibration based bearing fault diagnosis.

Example:
load('s4.mat');
signal=s4;
Fs=12000;
envelope(signal,Fs);

The File 's4.mat' is the vibration signal recorded from a OR faulty
bearing with a sampling frequency of 12000Hz. The Fault frequency is 161Hz and is brought out in envelope signal which was hidden in the original FFT.

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Author:Santhana Raj.A
https://sites.google.com/site/santhanarajarunachalam/