memeth
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Hi all,
I am actually a mechanical engineering student and i have almost no experience in signal processing. My thesis topic is related to "electrical signature analysis" and i have some questions about filtering signals and comparing them to eachother.
I have some signal vectors that i need to filter high frequency components. First of all, by using fft function, i have plotted frequency vs. amplitude figure. I observed the figure and decided to filter frequency components higher than a certain peak amplitude frequency. (By the way, i am still not sure how to decide on N value while using fft(X,N). I decided on a value of N which is a power of 2 and greater than the length of my signal vector.) Then, i used [B,A] = BUTTER(N,Wn,'low') function to filter out high freq. components. But, i don't know what N really is. Matlab help says that it is the order of the filter so i used a value of 10. How can i decide on the value of N? and moreover, i used Wn = 500/fs Hz. (500 is the cut-off frequency that i decided and fs is the sampling frequency.) How can i decide on the value of fs? i used the N value that i used in fft(X,N) as my fs. Can you please help me? Anyway, i could filter my signal but i want to be sure that i don't make mistakes.
After filtering my signals, i have to compare them to eachother to see whether they are "similar" or not. Do you have any suggestions to do that? The first thing i thought was to use power spectral density or maybe kurtosis or variance. I would be grateful if you suggest me and options, so that i can study accordingly.
Thank you very much.
I am actually a mechanical engineering student and i have almost no experience in signal processing. My thesis topic is related to "electrical signature analysis" and i have some questions about filtering signals and comparing them to eachother.
I have some signal vectors that i need to filter high frequency components. First of all, by using fft function, i have plotted frequency vs. amplitude figure. I observed the figure and decided to filter frequency components higher than a certain peak amplitude frequency. (By the way, i am still not sure how to decide on N value while using fft(X,N). I decided on a value of N which is a power of 2 and greater than the length of my signal vector.) Then, i used [B,A] = BUTTER(N,Wn,'low') function to filter out high freq. components. But, i don't know what N really is. Matlab help says that it is the order of the filter so i used a value of 10. How can i decide on the value of N? and moreover, i used Wn = 500/fs Hz. (500 is the cut-off frequency that i decided and fs is the sampling frequency.) How can i decide on the value of fs? i used the N value that i used in fft(X,N) as my fs. Can you please help me? Anyway, i could filter my signal but i want to be sure that i don't make mistakes.
After filtering my signals, i have to compare them to eachother to see whether they are "similar" or not. Do you have any suggestions to do that? The first thing i thought was to use power spectral density or maybe kurtosis or variance. I would be grateful if you suggest me and options, so that i can study accordingly.
Thank you very much.