How the input signal get multiplied with the window functions like Hamming, Hanning, Blackman, etc?
- How is the multiplication perfomed ?
The input signal is $1\times 64$ row matrix, the Blackman window generates its samples in $64\times 1$ column matrix. The multiplication generates a $64\times 64$ matrix i.e one sample of input signal is multiplied to 64 samples of the window function. For a particular point sample there are 64 sample value. I intend to calculate 128-point FFT with padding zeros.
- So for a particular sample point which value should be considered to calculate FFT?
Here is my code :
N = 64; % signal length (power of 2) T = 10*(10^-9) ; % sampling period (and rate) is set to 1 A = 1; % sinusoid amplitude phi = 0; % phase of zero f = 10*(10^6); % frequency (under Nyquist limit) nT = [0:N-1]*T; % discrete time axis w = blackman(N,'periodic'); x1 = A*cos(2*pi*f*nT); x = w*x1 ; % windowed signal subplot (311); stem (x1); wp = [w;zeros((zpf-1)*N,1)]; subplot (313); stem (x); subplot (312); stem (w); disp (x1); disp (w); disp (x);