I think I remember that the fourier transform is used to send a signal across a analog line, for DSL modems, after it's converted from binary. Since analog lin

I think I remember that the fourier transform is used to send a signal across a analog line, for DSL modems, after it's converted from binary. Since analog lines may not have the same frequency response when it comes to interference, the modem usually tests the analog lines at various frequencies, and only keeps the intervals who are good enough to transmit. I wonder if the FFT is used for wifi, since wifi passes through an analog signal. Although I'm not even sure of what I'm talking about is true or relates to fourier.