Sinusoids

Available under Creative Commons-ShareAlike 4.0 International License.

Discrete-time sinusoids have the obvious form s (n)= Acos (2πfn + ϕ). As opposed to analog complex exponentials and sinusoids that can have their frequencies be any real value, frequencies of their discrete-time counterparts yield unique waveforms only when f lies in the interval
This choice of frequency interval is arbitrary; we can also choose the frequency to lie in the interval [0,1). How to choose a unit-length interval for a sinusoid's frequency will become evident later.