how to apply butterworth filter in frequency domain

hello i want to apply bandpass But I don't know how to apply it to the actual code.

I would like to apply the bandpass filter that does not fall off the edge sharply to the actual file.

But I don't know how to pass only the frequency values shown in the picture in the butterworth function code

I don't understand most button codes because they use normalized frequency.

If the passing frequency is between 50 MHz and 100 MHz, how do I make a code?

Answer 1

[Pratheek]

You can use the following code to implement butterworth filter (bandpass). For more information visit Documentation.

Fs = 500; % Sampling
Fc1 = 50; % Lower cutoff
Fc2 = 100; % Upper cutoff
N = 4; % Filter order

% normalized cutoff frequencies
Wn1 = Fc1 / (Fs/2);
Wn2 = Fc2 / (Fs/2);

% Design the Butterworth filter
[b, a] = butter(N, [Wn1, Wn2], 'bandpass');

% use your custom signal
filtered_signal = filter(b, a, signal);

[영우]

Thank you very much for your reply. I have a question, is the signal that passes through the bandpass filter output as the signal of the time domain? The signal looks like a time domain signal, not a frequency domain

The result I wanted was a graph result that would make everything zero except for the frequency band that could pass through the bandpass filter