We plot the Discrete Time Fourier Transform of a sinusoidal signal \[ x[n] = \cos(2\pi \nu n), \] given by \[ X(\nu) = \frac{1}{2} \sum_{n\in\mathbf Z} \delta_{\nu - n} + \delta_{-\nu + n}. \]
By comparing with the continuous time sinusoidal signal \( x_c(t) = \cos(2\pi \nu t), \), we observe spatial aliasing.