display FFT of a signal

[luckyloic]

Hello

I have a noisy signal to process (Please find enclosed an image of the signal) and I would like to use the FFT function on my signal to filter the noise and retrieve the clean signal by using the FFT inverse.

I have trouble when I use FFT because I just have one peak while I am expected to have a curve and the the noise on higher frequencies.

Thanks

[rpursley8]

You didn't attach the data

[luckyloic]

Here is the signal I want to process

Thanks

[rpursley8]

I'm sure there is other signals present, but your one peak is at DC (0 Hz) and is orders of magnitude larger than any other frequency present.  If your signal really starts at 28000, at least subtract that out from all points before performing the FFT.  You might try viewing it on a log scale as well.

[luckyloic]

Hello

Please find enclosed the output of my signal using FFT. I have complex values in my output array.

How can i extract the noise now to clean the signal and retrieve it in the temporal field.

Thanks for your help

[rpursley8]

Can you post your data instead of just a picture of your data?

[luckyloic]

Here is my VI with the image

Let me know if it is enough

Thanks

[rpursley8 · Accepted solution]

Take a look at the attached and see what I added.  Changes the window size will change the cutoff for the filtering.  I offset the result by one just to make it easier to see in the Waveform Graph.

[luckyloic]

Hi

Thank you for the attached file.

I have some questions to understand your VI

What is the meaning of the window? Does it represent how much noise is extracted. What represents the center of hte window where the peak is located.

Else it works very well, thanks.

[rpursley8]

The window is a lowpass filter.  This is a basic square window.  The center represents 0 Hz (or DC).  Positive frequencies to the right, negative frequencies to the left.  So this windows zeros out the frequency components that fall outside the window.