I am getting very confused with the textbook I am reading through: Modern Digital and Analogue Communication Systems:
3.8.1 Parseval's Theorem says that:
The total power in a power signal is its time average energy.
It then goes onto section 3.8.2 where it says that the Autocorrelation function is:
In terms of a discrete sampled signal if I have a signal and I am calculating the autocorrelation function and I get to tau=0. Is that just the energy of the signal? g(t)*g(t-0)=E_gt
But then the text goes on to say that the PSD is the Fourier Transform of the Autocorrelation Function.
How is that possible? if tau=zero, then that one calculation captures the energy in the signal. I haven't even considered the other taus. Wouldn't I go well above the actual energy in the signal?