Tutorial

1. Tutorial-1
(Fourier Transform implementation in
Matlab )
EE-202 (Signal and systems)

2. Overview
• Introduction
• Fourier transform (FT)
• Relation between Fourier methods
• Basic Matlab code for FT
• References

3. Introduction
• Transform: A mathematical operation that takes a function or sequence
(one domain) and maps it into another one (other domain)
• We need signal transforms because
– The transform provides hidden information about the original function
or signal
– The transform helps to solve a differential equation
– The transform may provide data compression and storage may require
less memory
– Some operations may be easier to apply in the transform domain
(Example: Convolution operation in LTI systems).

4. • Fourier transform is like a bridge between time domain and frequency domain
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Fourier Transform
Time domain f(t) Frequency domain f(w)
FT
IFT

5. Relation between Fourier methods
FFT is for implementation of DFT

6. Basic Matlab code for FT
• FFT- Fast Fourier transform (fast algorithm for implementation of discrete
Fourier transform). Y = fft(X,n,dim)
• IFFT- Inverse fast Fourier transform. X= ifft(Y,n,dim)
• abs()- Calculate magnitude of spectrum. mag = abs(fft(X,n,dim))
• angle()- Calculate phase of spectrum. phase = angle(fft(X,n,dim))

7. Assignment
• Solve one question numerically and also implement on Matlab.
• See the effect of change in amplitude in time domain signal on spectrum.
• Effect of number of FFT point.