MATLAB: To design a 4pole butterworth band pass filter in frequencies 0.34Hz-1Hz with double pass filtering scheme.

bandpassbutterworthpoles

Hi, I am new to the matlab coding. I want to design a 4pole butterworth bandpass 0.34-1Hz filter. The order and ripples are not specified. The sampling frequency is 20Hz. Double pass filtering scheme should be implemented. Is this is possible in matlab?

[b,a]=butter(2, [0.34 1]/(20/2), 'bandpass'); dataout=filter(b,a,datain);

I did above code for filtering. Is this correct.

How I can implement double pass filtering scheme to this?

Any response would be greatly appreciated. Thanks in advance.

Best Answer

The ‘double pass filtering scheme’ probably refers to using the filtfilt function.

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: Using zero-pole-gain Butterworth filter

The zero-pole-gain is a good start. To filter your data, I would convert it to second order section implementation for stability, then use that to filter your data. Use the filtfilt function to do the actual filtering, since it has a maximally flat phase response and so does not produce any phase distortion in your filtered signal.

It is always good to be certain your filter is doing what you want by using the freqz function first.

Try this:

[z,p,k] = butter(n,Wn,ftype);
[sos, g] = zp2sos(z, p, k);
figure(1)
freqz(sos, 2^16)
dataOut = filtfilt(sos, g, dataIn);

That should work.

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: Using zero-pole-gain Butterworth filter

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