Given an hidden law $$I(t)=\frac{1}{2}[A+B.cos(2\pi\nu_0t+\phi_0)]$$ I observe its signal with 256 samples and compute its FFT over this interval, and represent the FFT result from 0 to 1 (normalised frequency).
I get a figure whose pic is at 0.83.
How can I retreive A,B and $\phi_0$ from this graphics ?
A second question is : is it normal that this figure is not symmetric ?
A final question is : doing an analytical computation on classical Fourier transform gives a result. How much does what I observe from FFT and the analytical result differ ?
homework
tag. It seems like that to me, so here are some hints: (1) A is like a DC component. Its frequency is 0. (2) A real signal's FT is symmetric. A complex signals doesn't have to. (3) A FT has both magnitude (which I believe you are plotting) and phase. $\endgroup$ – Serge Mar 8 '13 at 16:58