Let {a_i}_(i = 0)^(N - 1) be a periodic sequence, then the autocorrelation of the sequence, sometimes called the periodic autocorrelation, is the sequence ρ_i = sum_(j = 0)^(N - 1) a_j a^__(j + i), where a^_ denotes the complex conjugate and the final subscript is understood to be taken modulo N.

average power | convolution | correlation | cross-correlation | quantization efficiency | recurrence plot | Wiener-Khinchin theorem