How to envelope a FFT dataset?

Hi,

I have an excel file of FFT data including frequency, amplitude and phase of a bearing signal. I want to montitor the condition of the bearing using elvelope method.

How can i plot x-t of the signal and also find envelope of this signal?

Answer 1

[Star Strider]

It depends on what you want to do. The Signal Processing Toolbox has the envspectrum function that can do this, however the signal must be in the time domain, so that would require either using that signal (if you have it) or using ifft with the Fourier transformed data. A more direct approach would be to use the envelope function with the absolute value of the Fourier transform (so the frerquency and magnitude values only), most likely using the 'peak' option. (I have not done machinery diagnosis so I have not used envspectrum, however I am familiar with envelope.)