How do we apply Discrete Time Fourier Transform (DTFT) to the signal? what is the difference between DFT, DTFT and FFT?

I am now doing my research on vibration analysis. throughout my research, Ive found that Dirichlet fourier transform is refering to DTFT. but still I do not understand on how to apply DTFT to the signal? is it same function like DFT and FFT?

please help me. I am new in Matlab and signal processing.

Answer 1

[Star Strider]

I’m not certain how you’re applying the Dirichlet kernels (I’ve never used them), but the MATLAB fft function should do what you want. I always considered ‘DTFT’ to be the ‘discrete time Fourier transform’, the Fourier transform applied to discretely-sampled signals of the sort that you will be dealing with in your research.

[HAKD]

i have time domain signal. means, i will have to perform fft through DTFT? what is the different between Discrete Fourier Transform and DTFT?

Thanks for answering sir!

[Star Strider]

I am not certain there is a significant difference. If your instructor wants you to code and use the Dirichlet kernels, then do so. (I have never used them, so I have no experience with them. They are not in any of my signal processing textbooks.) If you want to be certain your fft analysis conforms to the Dirichlet conditions (and your signal needs to meet them for your analysis to be accurate), you need to determine that yourself.

I would just use the fft function. It does a Discrete Time Fourier Transform by definition.