Periodic CT Signal:
A CT signal X(t) is called **periodic** if there exists T>0 period such that X(t+T)=X(t),for all values of t. The **fundamental period** is the smallest period of all periods of a signal (denoted by <img alt="tex:T_0" style="vertical-align: middle;" />).
Periodic DT Signal:
A DT signal X[n] is called **periodic** if there exists N>0 period such that X[n+N]=X[n],for all values of n. the **fundamental period** is the smallest period of all periods of a signal (denoted by <img alt="tex:N_0" style="vertical-align: middle;" />)
Note that the period N must be an integer in DT, but that the period T in CT can be any positive real number.
