Parsavel's Theorem

$\frac{1}{T_0}{\int }_{t_0}^{t_0+T_0}|x(t){|}^2\mathrm{d}t=\sum _{k=-\infty }^{\infty }|c_k{|}^2$

• Says the signal power in the time domain is the same as the sum of powers of its frequency components