And Because the spectrum of the discrete time sign, this similar spectrum will periodically repeat if we extended the frequency better outside of $f_s$ these kinds of the spectrum proven is also the same spectrum in each and every frequency band from $nf_s$ to $(n+one)f_s$ for almost any integer $n$. https://1rkforrentgurgaon.blogspot.com/2025/07/book-spacious-boys-pg-in-sector-15-part.html