(Math lab Question)

(Math lab Question) Find an audio signal and use a low pass filter with cut off frequency 4KHz to filter the signal. Plot the output and the input signal and comment on the result.

[Jan]

This is a homework question. So please post, what you have tried so far and ask a specific question. It would not be smart, if the forum solves your homework.

Answer 1

[Image Analyst]

Hint:

signal = .....
ft = fft(signal); % Get spectrum
ft(index1:index2) = 0; % Zero out frequencies higher than 4 kHz
filteredSignal = ifft(ft); % Back to time domain
plot(filteredSignal, 'b-', 'LineWidth', 2);
grid on;

Hint: index1 and index2 will be in the middle of the array, not at the beginning or end since I didn't call fftshift(). Recall that the zero freq place is at the first and last element of the array and higher frequencies go inward from the ends.

Answer 2

[SRIRAM G]

f = 0:n-1