trouble making a firfilter to remove a tone out of a wavefile

2 次查看（过去 30 天）

Jacob 2023-11-29

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2053422-trouble-making-a-firfilter-to-remove-a-tone-out-of-a-wavefile

评论： Jacob 2023-11-30

I am trying to write a matlab code to design a firfilter to filter a tone out of a wav.file but I am having trouble getting the filter to work this code below is supposed to determine the frequencies of the audio in the wav.file and filter the tone out of the sunshinesquare.wav file. however when I go to run the program matlab tells me there is an error with the notchfilter line but I can't figure out what is wrong with it any suggestions/help is greatly appreciated.

My code is below

[x, fs] = audioread('SunshineSquare.wav'); 
X = fft(x); 
f = linspace(0, fs/2, length(X)/2);
[~, f0] = max(abs(X(1:length(X)/2))); 
notchFilter = fdesign.notch('N,Fc', 100, f0, fs); 
b = firpm(notchFilter); 
y = filter(b, 1, x); 
sound(x, fs);

3 个评论
显示 1更早的评论隐藏 1更早的评论

Walter Roberson 2023-11-29

Error using fdesign.abstractpeaknotch/set.Specification

Expected Specification to match one of these values:

'N,F0,Q', 'N,F0,Q,Ap', 'N,F0,Q,Ast', 'N,F0,Q,Ap,Ast', 'N,F0,BW', 'N,F0,BW,Ap', 'N,F0,BW,Ast', 'N,F0,BW,Ap,Ast'

The input, 'N,Fc', did not match any of the valid values.

Chunru 2023-11-29

issues with making a matlab firfilter - MATLAB Answers - MATLAB Central (mathworks.com)

请先登录，再进行评论。

请先登录，再回答此问题。

采纳的回答

Walter Roberson 2023-11-29

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2053422-trouble-making-a-firfilter-to-remove-a-tone-out-of-a-wavefile#answer_1361867

编辑：Walter Roberson 2023-11-29

在 MATLAB Online 中打开

The error is correct, in that the documentation lists specific filter specifications, none of which include Fc

https://www.mathworks.com/help/dsp/ref/fdesign.notch.html#d126e434241

I do not promise that I calculated f0 correctly.

[x, fs] = audioread('SunshineSquare.wav'); 
X = fft(x); 
L = floor(length(X)/2);
f = linspace(0, fs/2, L);
[~, f0idx] = max(abs(X(1:L))); 
f0 = (f0idx-1)/L;
Q = 80;
notchFilter = fdesign.notch('N,F0,Q', 100, f0, Q); 
Hd = design(notchFilter, 'SystemObject', true);
y = Hd(x);
sound(y, fs)

18 个评论
显示 16更早的评论隐藏 16更早的评论

Walter Roberson 2023-11-30

在 MATLAB Online 中打开

The audiofile has a primary frequency and two further peaks at 2 and 3 times the primary. Removing those three leaves only low level information.

X = fft(x); 
L = floor(length(X)/2);
f = linspace(0, fs/2, L);
[~, f0idx] = max(abs(X(1:L))); 
f0 = (f0idx-1)/L;
Q = 2.5;
notchFilter1 = fdesign.notch('N,F0,Q', 6, f0, Q); 
notchFilter2 = fdesign.notch('N,F0,Q', 6, f0*2, Q);
notchFilter3 = fdesign.notch('N,F0,Q', 6, f0*3, Q);
Hd1 = design(notchFilter1, 'SystemObject', true);
Hd2 = design(notchFilter2, 'SystemObject', true);
Hd3 = design(notchFilter3, 'SystemObject', true);
y = Hd3(Hd2(Hd1(x)));
tiledlayout('flow');
nexttile
plot(f, abs(X(1:L))); title('original spectrum');
nexttile
Y = fft(y);
plot(f, abs(Y1(1:L))); title('filtered spectrum');

Jacob 2023-11-30

Awesome Thank you! It works and I don't hear the tone anymore which is what I needed! One more thing the end of the file is still a little noisy but I can hear the file is there a way to clean the file up or is it what it is? I know there is only so much that can be done cleaning up an audio file so I am happy with what I have if not.

请先登录，再进行评论。