Design a third order low pass butterworth filter

I want to design a 3rd order butterworth filter with a cutoff frequency 160 rad/s. The input signal is a square wave with magnitude of +-1V. and fundemental frequency of 130 rad/s. I must use butter(N,Wn,'s') command. And i have to find the magnitude and phase spectra of the filter.

[Adam]

What's the question? You want someone to do it all for you? If not be more precise what you are stuck on.

[Star Strider]

Please read the friendly documentation!

[Group 1]

[Group 1]

I'm stuck in (ii)

[Star Strider]

‘I'm stuck in (ii)’

No, you aren’t.

I specifically told you what function to use and how to use it in your other (essentially duplicated) post.

If you don’t want to read the documentation or even the correct Answers to your Questions, I suggest that you drop this course, and all other courses using MATLAB (and that covers all engineering and most other scientific disciplines).

[Star Strider]

‘Im stuck in (iii) now.’

You need the Spectrum Analyzer in Simscape. I don’t have Simscape, so you’re on your own.

For the MATLAB part, are you familiar with the Fourier transform?

[Group 1]

Yes I'm. but not in matlab.

[Star Strider]

Well, I suppose you could look it up yourself.

Read fft (link) for some necessary enlightenment.

[Group 1]

Can i compute it without sampling frequency? all the examples mention it. but its not given in the question

[Star Strider]

You can compute the Fourier transform without the sampling frequency. The results will not provide you with any information with respect to frequency.

Answer 1

[David Barry]

Read the doc and follow one of the very similar examples. If you are still stuck after that then upload your code and specific question. https://uk.mathworks.com/help/signal/ref/butter.html

[Group 1]

This is the question

[Group 1]

[David Barry]

What have you tried so far?

[Group 1]

freqs worked for (ii). Im stuck in (iii) now.