# Tag Info

As a simple example, consider the discrete-time signal $$x[n]=a^nu[n],\qquad |a|<1\tag{1}$$ where $u[n]$ is the unit step function. The discrete-time Fourier transform (DTFT) of $x[n]$ is given by $$X(e^{j\omega})=\frac{1}{1-ae^{-j\omega t}}\tag{2}$$ Note that $\omega$ is a normalized angular frequency: $$\omega=2\pi f/f_s\tag{3}$$ where $f_s$ is ...