Question

I am learning DSP and I couldn’t write a code to calculate and plot these figures (just magnitude of Hanning and triangular windows in frequency domain.) Could anyone please help me with the code?

I’ve read something related to online FFT, and, for example, they calculate online FFT with 1024 time steps. I don’t understand what is 1024 time steps, and what are the influences of time step value to FFT analysis?

Answer 1

I hope the following piece of code is helpful to you.

L = 10;
win1 = hanning(L);
win2 = triang(L);
nfft = 64;
S1 = fft(win1,nfft);
S2 = fft(win2,nfft);
f = 1:nfft/2+1;
plot(f,10*log10(abs(S1(1:nfft/2+1))),'.-',f,10*log10(abs(S2(1:nfft/2+1))),'o-');

Annotation:

You can put win1 and win2 as Time-series signal. L is the length of win1 or win2. nfft is the length of FFT . if L < nfft , then the function fft() will add 0 to the rest of nfft. If L > nfft, then the function fft() will interception the length of L to equal nfft.