# How to Find the Frequency Response of a Communication Channel from Input and Output Symbols in MATLAB?

I want to find the channel frequency response of a digital communications system. I have the functions of the input symbol (a triangle) and the output symbol - a distorted triangle: $$\dfrac{1}{1 + \left( \frac{2t}{T} \right)^2 }$$ I want to plot the frequency response of the channel as if it was a digital filter.

How can I do this in MATLAB?

I tried using symbolic variables, computing Fourier transforms of the input and the output signal using fourier command, and then finding the numerical values using subs and double commands, with no success.

$$\frac{{X}_{Out}(f)}{{X}_{In}(f)}$$