1. Net 222: Communications and networks fundamentals (Practical Part)
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Lab 3: Matlab – Sinusoidal&Exercises

2. Sinusoidal Time & Frequency domain continuous or discrete signals
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3. continuous or discrete signals
Continuous-Time Signals:
A signal is continuous-time signal if the independent variable t is continuous.
Discrete-Time Signals:
A signal is defined at discrete times, a discrete-time signal is often identified as a sequence of numbers, denoted by
A very important class of discrete-time signals is obtained by sampling a continuous-time signal
IN MATLAB: command plot used to sketch the continuous time signals
IN MATLAB: command stem used to sketch the discrete time signals
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4. Plotting Time domain using Matlab
concept
A general sine wave in time domain can be represented by three parameters :
Peak amplitude (A)
Frequency (f)
Phase (φ)
s(t) = A sin(2π f t +Φ)
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5. Plotting Time domain using Matlab
Example
Example:
Plot and stem the time domain signal
7*sin(2*pi*2000*t+pi), t=0:0.05:3
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6. Plotting Frequency domain using Matlab
concept
Using discipline Known as Fourier analysis (any signal is made up of components at various frequencies, in which each component is a sinusoid ).
Eg. s(t) = [(4/π) x (sin(2πft) + (1/3) sin(2π(3f)t)]
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7. Plotting Frequency domain using Matlab
example
Plot each signals alone the show the frequency domain( Fourier) signal
s(t)=[6*sin(2pi*t+pi)+4*sin(2*pi*3t+pi)+ 2*sin(2*pi*5t+3*pi)]
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8. Networks and Communication Department

9. Exercises Contents Basic exercises Arrays & Matrices Plotting
Sinusoid Sampling
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10. Basic exercises Let vector x = [5 2 1 6]: Add 16 to each element
Let y = [ ], multiply x*y A. B.
Adding 16 to vector x in matlab
Multiplying two vectors x and y
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11. Basic exercises
Evaluate the following MATLAB expressions by your hand and use MATLAB for checking your ans.:
2 / 2 * 3
(6 - 2 ) / ^ 2 – 1 A. B.
Hands calculation:
2/2=1
1*3 = 3
In Matlab:

12. Basic exercises Let vector t= 2, 4, 6, 8…20: Compute cos^2(t)
%Notice that vector t is a starting form 2 and incremented by 2 till 20
% cos^2(t) is written as cos(t).^2
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13. Basic exercises Let vector t= 2, 4, 6, 8…20: Exp^t(1+ cos(3t))
%Notice that vector t is a starting form 2 and incremented by 2 till 20
% exp^t is written as exp(t).

14. Arrays & Matrices Given an array A = [ 2 4 1 6 7 2 3 5 9]
provide the commands needed to:
assign the first row of A to a vector called x1
%Array in matlab written as each rows separated by ;
%assign the first row till end
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15. Arrays & Matrices Given an array A = [ 2 4 1 6 7 2 3 5 9]
provide the commands needed to:
assign the last 2 rows of A to an array called y
% end-1 is row before the last row
% end is the last row
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16. Arrays & Matrices Given an array A = [ 2 4 1 6 7 2 3 5 9]
provide the commands needed to:
compute the square-root of each element of A
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17. Arrays & Matrices Transpose the following matrices:
B=[ ] A. B.
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18. Plotting Plot sin(x2) on the interval [-5,5].
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19. Plotting
2. Create three curve on the interval [0,2π] step π/ the curve equation y = sin(x), y2 = sin(x-.25), y3 = sin(x- .5);

20. Sinusoid Sampling
Sample the sinusoid x = sin(2 pi f t), where f = 2 kHz. And t=0:5T
Let x1 be the signal sampled at 10 kHz.
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21. Sinusoid Sampling
Sample the sinusoid x = sin(2 pi f t), where f = 2 kHz. And t=0:5T
Let x2 be the signal sampled at 3 kHz
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22. Sinusoid Sampling
Plot frequency domain sinusoid x = sin(2 pi f t), where fs= 8000 Hz. At different frequency tones start from 0 till 1, then multiplying the tones with 2
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23. The End
Any Questions ?
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