And Because the spectrum of a discrete time sign, this very same spectrum will periodically repeat if we extended the frequency higher further than $f_s$ these types of the spectrum shown is additionally the exact same spectrum in every single frequency band from $nf_s$ to $(n+1)f_s$ for virtually any integer https://share.evernote.com/note/ec977020-75ac-e09c-95e1-400f3287133a