Experiment # 5
MATLAB Implementation of Continuous Time Fourier Transform
5.1 Objective
        To understand and implement the CTFT using MATLAB.
5.2 Introduction to Fourier Transform
The Fourier Transform expresses the signal (or function) g(t) in the frequency domain, the signal
is described by a function G(f). The Fourier Transform is denoted by the symbol F[.] and inverse
Fourier Transform is represented as F-1[.], as
                        G(f) = F[g(t)]           and          g(t) = F-1[G(f)]
                                             g(t)  G(f)
To recapitulate,
where w=2 π f
5.3 MATLAB Functions
        fourier(): to calculate Fourier Transform
        ifourier(): to calculate inverse Fourier Transform
        int(): for symbolic integration
Steps:
        Define t and w as symbolic variable.
        Define function for which fourier transform has to be calculated.
        Calculate fourier transform by using in-built function or by using the definition of Fourier
         transform with the help of int() function.
      Define the range of frequency w.
      Substitute value of w in above calculated Fourier Transform function using command
       “subs()”.
      Plot w.r.t frequency w. To plot magnitude, use abs(X), for phase use angle(X), for real
       and imaginary part use real(X), imag(X) respectively.
5.4 Lab Tasks
   1. Compute and plot the Fourier Transform of the rectangular pulse and find inverse Fourier
       transform of rectangular pulse.
   Hint: Use bulit-in function heaviside() or rectangularPulse() to define rectangular pulse
   2. Compute and plot the Fourier Transform of the triangular pulse.
                Hint: Use built-in function triangularPulse() to define triangular pulse.
                                                                      2
   3. Compute and plot the Fourier Transform of the function e−t .
   4. Compute and plot the Fourier Transform of the impulse function. Use dirac() to define
       impulse function.
   5. Compute and plot the Fourier Transform of the function of cos 2 π f0t and sin 2 π f0t.
   6. Compute the Fourier transform of the signal e−t u(t) and compare the results with previous
       task. Plot magnitude, angle, real and imaginary part
                               Hint: To define u(t) use built-in function heaviside()
   7. Compute and plot the Fourier Transform of the function sinc(x) = sin( π x)/ π x and
      calculate inverse Fourier of sinc function.
5.5 Conclusion
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
__________________________________________________.