Designing a discrete signal with cutoff frequencies

How would I go about designing a 4th order band stop discrete filter that is designed to filter signals sampled at 10Hz and with cutoff frequencies of 2.65Hz and 3.3Hz using the FIR window approach?

Many thanks.

[AndresVar]

do you have the filter designer app? Introduction to Filter Designer - MATLAB & Simulink Example (mathworks.com)

Answer 1

[Star Strider]

Similarly to the previous filter in Designing a specific low-pass discrete filter in MATLAB —

Fs = 10;                                                % Sampling Frequency (Hz)
Fn = Fs/2;                                              % Nyquist Frequency
order = 4;
Fp = [2.65 3.3];                                        % Passband Frequency Vector
h = fir1(order, Fp/Fn, 'bandpass');

figure
freqz(h, 1, 2^16, Fs)

The order is too low for it to actually have a bandpass characteristic. Increasing the order shows it correctly —

Fs = 10;                                                % Sampling Frequency (Hz)
Fn = Fs/2;                                              % Nyquist Frequency
order = 12;
Fp = [2.65 3.3];                                        % Passband Frequency Vector
h = fir1(order, Fp/Fn, 'bandpass');

figure
freqz(h, 1, 2^16, Fs)

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