Discrete-Time Fourier Transform (DTFT)
- takes DISCRETE signal as input and outputs a CONTINUOUS frequency spectrum
- it’s defined by an infinite summation over the discrete-time signal
- while mathematically powerful, the DTFT is not directly computable on a computer because of its continuous nature and infinite summation
- thus Discrete Fourier Transform (DFT) - Discrete Fourier Series is a computationally efficient way to approximate the DTFT