The fundamental period of a periodic signal is the smallest amount of time it takes for the signal to repeat itself. A periodic discrete-time signal $x(n)$ that verifies the equation: $ x(n) = x(n+N),\ N \in \mathbb{Z} $ The fundamental period, $N_{0}$ is the smallest positive value of $N$ that verifies the previous equation. The inverse of the fundamental period is the [[fundamental frequency]] expressed in Hz or samples per second: $ f_{0} = \frac{1}{N_{0}} $