무선통신개론 2판, 28 ~ 32p 정리
https://en.wikipedia.org/wiki/Nyquist%E2%80%93Shannon_sampling_theorem
https://en.wikipedia.org/wiki/Discrete-time_Fourier_transform#Relation_to_Fourier_Transform
https://www.ti.com/video/5527868103001#tab-1
https://jaeseolee3754.tistory.com/34