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  1. #1
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    matlab butter

    I am trying to design a low pass filter using butter filter in matlab I am confussed how to od this. If my carrier Fc is 20000,( but can be changed if needed) and Fs is 44100 (MP3 file) what do I put in the matlab function below? Please help me I can not get htis please??
    I need to filter: outfm = Ac * cos(wc.*t + 2 * pi * kf * cumsum(snd));
    Fc=20000
    Fs=44100

    [N, Wn] = BUTTORD(Wp, Ws, Rp, Rs)

    loses no more than Rp dB in
    the passband and has at least Rs dB of attenuation in the stopband.
    Wp and Ws are the passband and stopband edge frequencies, normalized
    from 0 to 1 (where 1 corresponds to pi radians/sample).

    •   Alt6th December 2005, 02:53

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  2. #2
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    butter matlab

    Try to use fdatool, just type fdatool on Matlab and it will give you a GUI of a filter design...it really help coz it also displays the different responses of the filter you just designed



    •   Alt6th December 2005, 03:03

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  3. #3
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    matlab lpf

    try this
    [N, Wn] = BUTTORD(Fc/Fs, Fstop/Fs, Rp, Rs)



    •   Alt11th December 2005, 14:48

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  4. #4
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    lpf matlab

    Quote Originally Posted by locchamp
    I am trying to design a low pass filter using butter filter in matlab I am confussed how to od this. If my carrier Fc is 20000,( but can be changed if needed) and Fs is 44100 (MP3 file) what do I put in the matlab function below? Please help me I can not get htis please??
    I need to filter: outfm = Ac * cos(wc.*t + 2 * pi * kf * cumsum(snd));
    Fc=20000
    Fs=44100
    Try this, if you didn't get result up to now:

    Fc=20000;
    Fs=44100;
    Fstop=21500; % stopband frequency
    Rp = 0.1; % 0.1 dB loss in passband
    Rs = 40; % 40 dB attenuation in stopband
    [N, Wn] = buttord(Fc/(Fs/2), Fstop/(Fs/2), Rp, Rs);
    [B,A] = butter(N,Wn);



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