This example code was used to answer a question about applying a window on the Fourier amplitude spectrum. How to apply Hamming Window?
I have a question about the section of code related to the variable
mYdft. It's altered 3 times and I'm not sure why. Could someone elaborate on what's going on here?
Complete example code for reference:
Ts = 50e-6; % Sampling Time(s) Fs = 1/Ts; % Sampling rate, Sampling Freq (Hz) f0 = 50; % Frequency of interest (Hz) duraT = 1; %Calculate time axis dt = 1/Fs; tAxis = dt:dt:(duraT-dt); y = cos(2*pi*f0*tAxis) + 2*sin(2*pi*10*tAxis); y=y'; L = length (y); % Window Length of FFT nfft = 2^nextpow2(L); % Transform length y_HannWnd = y.*hanning(L); Ydft_HannWnd = fft(y_HannWnd,nfft)/L; % at all frequencies except zero and the Nyquist mYdft = abs(Ydft_HannWnd); mYdft = mYdft (1:nfft/2+1); mYdft (2:end-1) = 2* mYdft(2:end-1); f = Fs/2*linspace(0,1,nfft/2+1); figure(1), subplot(2,1,1) plot(tAxis,y) title('Time Domain y(t)'); xlabel('Time,s'); ylabel('y'); subplot(2,1,2) plot(f,2*mYdft); % why need *2 ? Bcoz, Hanning Wnd Amplitude Correction Factor = 2 axis ([0 500 0 5]); %Zoom in title('Amplitude Spectrum with Hann Wnd'); xlabel('Frequency (Hz)with hanning window');