Question

Using Matlab Simulink, find Fourier transform of the following signal;

?(?) = 2 + ∑
1 ?
sin (20???)
4
?=1
.

Set simulation stop time = 20 seconds, sample time = (1/1024) seconds, buffer size =1024, and frequency range in Hz for the vector scope is −100 ≤ ? ≤ 100

Answer 1

From the above simulink diagram, it is seen that the stop time has been selected as 20 sec. The individual block parameters are shown below

for sine wave block 1, frequency in Hz would be 10 Hz, thus, in radian scale it would be 10*2*=20*. The corresponding block parameters are shown below for each sine wave blocks

sine wave block 1

sine wave block 2

sine wave block 3

sine wave block 4

The plot of the result time signal at the time scope is shown below

Now, for the spectrum analyzer block to get the frequency spectrum within the range of -100 Hz to +100 Hz, the following settling needs to be done

after the simulation, the spectrum analyzer fft output is shown in the above diagram.