How to apply hamming window for a frequency domain signal?

Please help me with the matlab code... For example, consider a noisy sinusoidal signal. After computing the fourier transform, it will show spikes at fundamental frequencies present in the signal. Now, I want to reduce the noise by multiplying it with a hamming window. How can i do it...???

Answer 1

[Carlos]

Why can't you apply the Hamming window in the time domain, and then compute the FFT of the resultant signal?

On the other hand you can apply the the Hamming window in the frequency domain.First consider the following property of the Fourier Transform

FFT(f*h)=convolution(FFT(f)*FFT(h))

So you can compute the FFT of your Hamming window and then calculate the convolution of your function in the frequency domain with the frequency domain of your Hamming window.

However it is much easier if you apply the Hamming window in the time domain, and then study the effects in the frequency domain.