I am trying to filter off two unwanted terms in this frequency spectrum (the spectrum on top). First, I used a convolution between a rectangular window to make the unwanted terms equal to zero.
the first problem is when I tried to centralize the remaining part and multiplying it by a cos ( 2 * pi * f *t) I didn't get any result.
And my second question about hamming window is that in an article about a similar issue, a hamming and a blackman window were used. So, is it possible to use hamming window to filter off the unwanted terms? if yes, then how do I choose the starting and the final point of the hamming window to leave only the desired part! I really need help to understand how does it work and how to use it.