How to properly filter

Hi,

I would like filter a cosinus wave with a Gaussian Filter. How to properly filter my signal with a Gaussian Filter ?

Thanks.

[Thomas Koelen]

What are you filtering?

[Anonyme Anonyme]

I am trying to implement a GFSK Modulation. So I want to filter the two cosinus waves before modulation.

Answer 1

[Image Analyst]

You can use conv(). Plug in the Gaussian signal, and your cosine signal, and you're done. Or you can use filter(). Is this homework?

[Image Analyst]

Anonyme's "Answer" moved here:

Is it correct to use 'same' in the function conv() to keep the same length before filtering ?

[Image Analyst]

Yes. That will give you an output signal only where the input signal is defined. But at the ends, you have only half a Gaussian because the peak of the Gaussian is at element 1 or the last element. If you want only elements where the Gaussian filter is completely contained in the signal, then use the 'valid' option. If you want the case where you get a signal when the right tail of the Gaussian just barely touches the left element of the signal, then use the 'full' option, which will give a signal that is longer than the original signal by the window width of your Gaussian.

Answer 2

[Star Strider]

Use the gaussdesign function in the Signal Processing Toolbox.

Use the upfirdn function to filter it.