MATLAB: How to implement Pass Band Filter

arrhythmiabiomedical signal processingecgfilters

I am following necessary pre-preocessing steps for arrhythmia classification as mentioned below.

I have re-sampled dataset of ECG signals to 200 Hz. Now, these signals need to filtered with Band-Pass Filter.

Sampling frequency of ECG signals = 200 Hz

How to implement PassBand filter on my resampled signals in MATLAB for following specifications.

-> Passband frequency range = 1 to 100 Hz (In above paper it is 2-48 but I want to design with 1 to 100 Hz)

-> Filter Type = Chebyshev II

My Re-sampling Code

ECG Database

Best Answer

The 200 Hz sampling frequency was the reason they could use the 2-40 Hz bandpass filter. If you’re dealing with atrial or ventricular tachyarrhythmias, and you need a 2-100 Hz passband, you will have to resample your signals at greater than 200 Hz. I would use 256 Hz, since that is a relatively common sampling frequency for EKGs, so you may be able to use some of them without resampling them at all.

Related Solutions

MATLAB: How to design FIR lowpass filter with cutoff frequency, fc1 = 20 Hz and FIR bandpass filter with cutoff frequency fc2 = 10 Hz and fc3 = 35 Hz.

Déjà vu

how to design IIR highpass filter with cutoff frequency of 20Hz and FIR bandpass filter with cutoff frequency of 10Hz and 15Hz?

Make the appropriate changes to get the cascaded filter you want.

MATLAB: Filter design parameter: radian/sec or 1/sec

The passbands and stopbands for the Signal Processing Toolbox filter functions are actually normalised to the closed interval [0, pi] radians. It is calculated as the passband and stopband frequency in Hz divided by the Nyquist frequency.

Example for frequency calculations for the filters your signal:

Ts = 0.002;                                             % Sampling Interval (seconds)
Fs = 1/Ts;                                              % Sampling Frequency (Hz)

Fn = Fs/2;                                              % Nyquist Frequency

Note that the highest frequency you can design in your filter is the Nyquist frequency, here 250 Hz.

An example of a Chebyshev Type II filter design for filtering an EKG signal is here:

Fs = 250;                                               % Sampling Frequency (Hz)
Fn = Fs/2;                                              % Nyquist Frequency (Hz)
Wp = [1.0   100]/Fn;                                    % Passband Frequencies (Normalised)
Ws = [0.5   101]/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(3)
freqz(sosbp, 2^17, Fs)
EKG_filt = filtfilt(sosbp, gbp, EKG_original);          % Filter EKG Signal

The filter passband goes from 1 Hz to 100 Hz.

Best Answer

Related Solutions

MATLAB: How to design FIR lowpass filter with cutoff frequency, fc1 = 20 Hz and FIR bandpass filter with cutoff frequency fc2 = 10 Hz and fc3 = 35 Hz.

MATLAB: Filter design parameter: radian/sec or 1/sec

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