Process raw data using lowpass filter
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Hi,
I have a excel file with raw data containg 1200 rows and 2 columns named A and B. I'm try to apply a lowpass filter on the signal but looks like its not working, hopefully someone on here may have time to guide me to the right direction.
here is what I did so far:
imported data as a table -> created a script -> inside of the script -> load rawdata.csv
% sampling frequency [Hz]
Fs = 1000;
% sampling period [s]
Ts = 1/Fs;
% time vector [s]
t = 0:Ts:3;
% Signal A
sig_A = rawdata(:,1);
% Signal A
sig_B = rawdata(:,2);
order = 4;
fcut = 8000;
[sig_A,sig_B] = butter(order,fcut/(fs/2),'low');
x = filter(sig_A,sig_B);
采纳的回答
Alberto Mora
2021-2-10
编辑：Alberto Mora
2021-2-10
You are confusing the filter coefficient with the raw signal.
Try this:
[b,a] = butter(order,fcut/(fs/2),'low');
sig_a_filt = filter(b, a, sig_A );
5 个评论
nam bui
2021-2-10
Hello, this is the updated code I have but when I plot it, there is not any output filtered appear on the figure.
% sampling frequency [Hz]
Fs = 1000;
% sampling period [s]
Ts = 1/Fs;
% time vector [s]
t = 0:Ts:3;
% Signal A , and 1 represent for first column of raw data in the excel file
sig_A = rawdata(:,1);
% Signal A , and 2 represent for first column of raw data in the excel file
sig_B = rawdata(:,2);
order = 4;
fcut = 8000;
[a,b] = butter(order,fcut/(fs/2),'low');
x = filter(a, b, sig_A);
x1 = filter(a, b, sig_B);
plot(x,x1)
Alberto Mora
2021-2-10
编辑：Alberto Mora
2021-2-10
Please, upload also raw data.
Moreover, when you create a comment in this forum, please use the "code" section for add your code, in orther to distinguish the text to the code.
Alberto Mora
2021-2-10
编辑：Alberto Mora
2021-2-10
Here a working example.
If this helps you, please consider to accept this post as "answer", as sign of gratitude.
Fs = 1000;
Ts = 1/Fs;% sampling period [s]
t = 0:Ts:3;% time vector [s]
sig_A = sin(3*2*pi*t)+rand(size(t))*0.1-0.05;% Signal A. I just create a noisy signal...
order = 4;
fcut = 10;
[a,b] = butter(order,fcut/(Fs/2),'low');
sig_A_filt = filter(a, b, sig_A);
figure;
plot(t, sig_A); hold on
plot(t, sig_A_filt);
legend('raw signal','filtered signal')
nam bui
2021-2-10
Rahim Nami
2022-10-13
Hi everyone
Please, mathematical formula or mathematical model of the codes used. you insert
thank you
r_nami@gmx.com
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