how can I make this nonstationary signal's dft graph?

how can i make such a signal graph with 5hz, 20hz, 50hz and 1000 smapling frequency?

Answer 1

[Prabhan Purwar]

Hi,

The following code illustrates a method to find DFT of a nonstationary signal.

a=1;
f=[5 20 50 1000];
for i=1:length(f)
t=linspace(0,0.3,2000);
y(i,:)=a*sin(2*pi*f(i)*t);
end
ynet=[y(1,:) y(2,:) y(3,:) y(4,:)];
plot(ynet);
yft=fft(ynet);
figure
L=length(yft);
f =  6.6667e+03*(0:(L/2))/L;
g=fftshift(abs(yft));
plot(f,g(4000:8000));

Refer to the following link for further information:

• https://www.mathworks.com/help/matlab/ref/fft.html (FFT)
• https://www.mathworks.com/help/matlab/ref/fftshift.html (fftshift)

[DOHYUN JANG]

thank you very much!