DFT, IDFT and DTFT

Hey

in my university we got for home work this problem:

we got an modulated rectangular pulse (meaning a rect function multiplied by a sine function).

we calculated its fourier transform, lets call it F(w) (meaning the continious time fourier transform - we actually calculated it, not on matlab)

and now this function F(w) is multiplied by exp(-j*K(w)) where K(w) is some function of w... and we need to compute and plot in matlab the Signal in time, meaning calculate the Inverse fourier transform. and they gave us a hint to use the FFT function.

i didn't manage to do it. if i understand correctly the FFT function calculates the DFT. i am familiar with the connection between the FT of a signal and the DTFT of the samples of that signal. and i also know that the DFT is simply sampling the DTFT... but with all that said i don't understand how to make the transition between one and the other on matlab.

i would like to please ask for a general explanation on this topic, and also on how to solve my specific problem where i "start" from the Continious fourier transform and need to get the signal in time.

thank you very much in advance

Answer 1

[Raunak Gupta]

Hi,

There are many Blogs provided by Steve for the understanding of Discrete Fourier Transform (DFT) and Discrete Time Fourier Transform (DTFT). You may refer to this blog for more explanation. There is a bucket of blogs for Fourier Transform from Steve in general which will help in thorough understanding of the topic. You may follow the below link to read those.

https://blogs.mathworks.com/steve/category/fourier-transforms/

Hope it helps!