Hi Utkarsh,
Designing “IIR Butterworth" and "Chebyshev" bandpass filters in MATLAB involves several steps, including reading the signal from a text file, designing the filters with specified cutoff frequencies, and applying these filters to the signal. The steps mainly include:
- Load the signal data from the text file using the ‘load’ function
- Specify the cutoff frequencies (c1 and c2) in hz, the sampling frequence and the order of the filter, and design the filters using the ‘butter’ and the ‘cheby’ functions.
- Use the ‘filter’ function to apply the designed filters to the signal.
A sample code for the above steps will look as follows:
% Step 1: Read the signal from a text file
signalData = importdata('filename.txt'); % Replace 'filename.txt' with your file name
% Step 2: Define filter specifications
fs = 1000; % Sampling frequency in Hz (adjust based on your data)
c1 = 100; % Lower cutoff frequency in Hz
c2 = 300; % Upper cutoff frequency in Hz
order = 4; % Order of the filter
% Normalize frequencies with respect to Nyquist frequency
nyquist = fs / 2;
wn = [c1 c2] / nyquist;
% Step 3: Design Butterworth Bandpass Filter
[b_butter, a_butter] = butter(order, wn, 'bandpass');
% Step 4: Design Chebyshev Type I Bandpass Filter
ripple = 1; % Ripple in the passband (dB)
[b_cheby1, a_cheby1] = cheby1(order, ripple, wn, 'bandpass');
% Step 5: Apply the filters to the signal
filteredSignalButter = filter(b_butter, a_butter, signalData);
filteredSignalCheby1 = filter(b_cheby1, a_cheby1, signalData);
For more information regarding the above functions, refer the following documentations:
- Butterworth filter: https://www.mathworks.com/help/signal/ref/butter.html#bucse3u-3
- Chebyshev type 1 filter: https://www.mathworks.com/help/signal/ref/cheby1.html
- IIR filter design: https://www.mathworks.com/help/signal/ug/iir-filter-design.html
- Filter function: https://www.mathworks.com/help/matlab/ref/filter.html
Hope this helps!
