Hi Nabil,
To plot the spectrum of a sampled signal in MATLAB, we can use the Fast Fourier Transform (FFT) to convert the time-domain signal into its frequency-domain representation.To learn more about 'fft' function in MATLAB, please refer to the following documentation link: https://www.mathworks.com/help/matlab/ref/fft.html
We can compute the two-sided spectrum and convert it to a single-sided spectrum to get the amplitude of the frequency components. We can define the frequency domain (`f`) for plotting and then visualize the single-sided amplitude spectrum. This will allow us to see the dominant frequencies present in the signal.
You can refer to the attached code snippet for better understanding:
Fs = 400;
T = 1/Fs;
L = 1000;
t = (0:L-1)*T;
f1 = 100;
f2 = 200;
x = 0.5+ cos(2*pi*f1*t) + 2*cos(2*pi*f2*t);
figure;
plot(t, x);
title('Time-Domain Signal');
xlabel('Time (s)');
ylabel('Amplitude');
X = fft(x);
P2 = abs(X/L);
P1 = P2(1:L/2+1);
P1(2:end-1) = 2*P1(2:end-1);
f = Fs*(0:(L/2))/L;
figure;
plot(f, P1);
title('Single-Sided Amplitude Spectrum of x(t)');
xlabel('Frequency (Hz)');
ylabel('|P1(f)|');
Happy Coding!
