How to apply bandpass filter

The attached signal file is of 20Hz sampling rate. Each row is a signal, i needed to to apply bandpass filter to each row and convert it in the frequency range 0.34 - 1 Hz.

Answer 1

[Star Strider]

This filter will do what you want:

D = load('ehgSignal.mat');
s = D.val';

Fs = 20;                                                % Sampling Frequency (Hz)
Fn = Fs/2;                                              % Nyquist Frequency (Hz)
Wp = [0.34 1.00]/Fn;                                    % Passband Frequencies (Normalised)
Ws = [0.30 1.05]/Fn;                                    % Stopband Frequencies (Normalised)
Rp = 10;                                                % Passband Ripple (dB)
Rs = 50;                                                % Stopband Ripple (dB)
[n,Ws] = cheb2ord(Wp,Ws,Rp,Rs);                         % Filter Order
[z,p,k] = cheby2(n,Rs,Ws);                              % Filter Design
[sosbp,gbp] = zp2sos(z,p,k);                            % Convert To Second-Order-Section For Stability

figure(1)
freqz(sosbp, 2^16, Fs)                                  % Filter Bode Plot

tv = linspace(0, 1, length(s))/Fs;                      % Time Vector (s)
s_filt = filtfilt(sosbp,gbp, s);                        % Filter Signal

figure(2)
plot(tv, s_filt)
grid

NOTE — The filtfilt function will operate on the first non-singleton dimension of ‘s’, so since ‘s’ is (12 x 35220), it is necessary to transpose it to filter along the rows ( columns in the transposed matrix).

[Elysi Cochin]

sir one doubt, so the result i want is in variable named "s_filt", right?

[Star Strider]

Yes. The ‘s_filt’ variable are the filtered signals.

You can name the vectors whatever you want, of course.

[muhammad faiz]

sorry sir, i already try this code and it has some error on it, after i run this coding it say that "Reference to non-existent field 'val'." what does this mean ?

Answer 2

[muhammad faiz]

excuse me sir, sorry for asking, i'm still new in using the matlab software. But i need to do a bandpass filter, which is i need to apply the band pass filter to the sound signal. right now i only knew how to play the audio file from the matlab and the file was in .wav format, how to get the .mat format from the file ? and how to apply the band pass filter coding sir ? i don't really understand about it. and what does the ehgsignal.mat mean ? i hope you can help me figure out this, thank you sir