How to implement Pass Band Filter?

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

Answer 1

[Star Strider]

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.

[Explorer]

Okay, I will replace 200 with 256. Please help me in designing filter.

I tried to follow the link you referred but got stuck in very first step.

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Step 1: Determing Order

As I have to design chebyshev type II, I started with following code but got error.

MATLAB Code

Fs = 256; % Sampling Frequency

Fn = Fs/2; % Nyquist Frequency

Wp = [2 100]/Fn; % Filter Passband (Normalised)

Ws = Wp .* [0.5 1/0.5]; % Filter Stopband (Normalised)

Rp=1; Rs= 10;

cheb2ord(Wp,Ws,Rp,Rs)

Error:

Error using cheb2ord (line 62) The cutoff frequencies must be within the interval of (0,1).

Why am I getting this error?

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[Star Strider]

Use this instead:

Ws = Wp .* [0.5  1.2]; % Filter Stopband (Normalised)

This design works, and produces a stable filter with good characteristics:

Fs = 256; % Sampling Frequency
Fn = Fs/2; % Nyquist Frequency
Wp = [2 95]/Fn; % Filter Passband (Normalised)
Ws = Wp .* [0.5 1.2]; % Filter Stopband (Normalised)
Rp=1; 
Rs= 50;

[n,Ws] = cheb2ord(Wp,Ws,Rp,Rs);
[b,a] = cheby2(n, Rs, Ws);
[sos,g] = tf2sos(b,a);

figure(1)
freqz(sos, 1024, Fs)

I changed some of the parameters because I prefer these results for an EKG filter. You can see in figure(1) that the passband works.