Error in fir1 (line 115) Wind = chkwindow(Wind,L);

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afef 2017-3-10

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https://ww2.mathworks.cn/matlabcentral/answers/329077-error-in-fir1-line-115-wind-chkwindow-wind-l

评论： Star Strider 2017-3-24

i'm trying to use low pass FIR filter for EEG siganl that i have downloded from http://physionet.org/physiobank/database/chbmit/ but i got this error message Error using fir1>chkwindow (line 290) The window length must be the same as the filter length.

Error in fir1 (line 115) Wind = chkwindow(Wind,L); my code is: load('C:\Users\del.dell-PC\Downloads\chb01_01_edfm.mat') x = plot(val(1,:)); Fs=200; t = linspace(0,1,Fs); fc = 32; Wn = (2/Fs)*fc; L =40; b = fir1(40,Wn,'low',hamming(L)); fvtool(b,1,'Fs',Fs) y = filter(b,1,x);

plot(t,x,t,y) xlim([0 0.1])

xlabel('Time (s)') ylabel('Amplitude') legend('Original Signal','Filtered Data')

how can i fix that and how can i define the downloded signal thank you

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采纳的回答

Star Strider 2017-3-10

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https://ww2.mathworks.cn/matlabcentral/answers/329077-error-in-fir1-line-115-wind-chkwindow-wind-l#answer_258092

在 MATLAB Online 中打开

In R2017a (and probably earlier versions), the hamming window is the default. You only need to specify it as:

Fs=200;
t = linspace(0,1,Fs);
fc = 32;
Wn = (2/Fs)*fc;
L =40;
b = fir1(40,Wn);
figure(1)
freqz(b, 1, 2^16, Fs)

I included the freqz call so you can see that it works. It is not necessary for the code, and can be deleted.

Remember to use the filtfilt function to do the actual filtering.

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afef 2017-3-15

编辑：Star Strider 2017-3-15

在 MATLAB Online 中打开

hi i should filter all the channel of EEG signal that i have download from physionet.org they told me that To convert from raw units to the physical units shown above, subtract 'base' and divide by 'gain'. but when i try to use the fir filter as you see in the code i got this error message Error using testdev2filtre (line 12) Input arguments must be 'double'. please i need your help and i have another question if you don't mind should i use the same filter for all the channel

thanks.

clc;
clear all;
close all;
load('C:\Users\del.dell-PC\pfe\base de donnée\patient sans crise\chb01_01_edfm.mat')
deriv1=(val(1,:)-0)/2.559375;
Fs=256;
t=(0:length(deriv1)-1)/Fs; %valeur du temps de tout échantillon%
figure (1),
y=plot(t,deriv1);
legend('FP1-F7');
d1=designfilt('lowpassfir','PassbandFrequency',0.15,'StopbandFrequency',0.2,'PassbandRipple',3,'StopbandAttenuation',60,'DesignMethod','equiripple');
a = filtfilt(d1,y);
figure (2),plot(a,'r');
legend(' FP1-F7 Filtré');