Lab No. 8 &9Communication Systems

Angle Modulation(Frequency Modulation and Demodulation

Phase Modulation and Demodulation)

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Angle Modulation

• Angle Modulation is modulation in which the angle of a sine-wave carrier is varied by a modulating wave. Frequency modulation (FM) and phase modulation (PM) are the two main types of angle modulation.

• In telecommunications and signal processing, frequency modulation (FM) is the encoding of information in a carrier wave by varying the instantaneous frequency of the wave.

• Phase modulation (PM) is a modulation pattern that encodes information as variations in the instantaneous phase of a carrier wave.

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Angle Modulation

Frequency Modulation Phase Modulation

Frequency Modulation

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Phase Modulation Visualized

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Matlab Code for Frequency & Phase Modulation

% Frequency and Phase modulation

clear all

clc

t =0:0.01:10;

Am = input('Enter Message signal Amplitude(Am) = ');

fm = input('Enter Message signal frequency(fm)=');

Ac = input('Enter Carrier Signal Amplitude(Ac) = ');

fc = input('Enter Carrier Signal Frequency(fc)=');

kf = input('Frequency Sensitivity(kf) = ');

kp = input('Phase Sensitivity = ');

Wm =2*pi*fm;

CCNA-LAB Course CECOS University of IT & Emerging Sciences Omer Mujahid©

Matlab Code for Frequency & Phase Modulation

m = Am*cos(Wm*t);

subplot(2,2,1);

plot(t,m);

hold on

title('Message Input Signal');

xlabel('Time --->');

ylabel('Amplitude --->')

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Frequency & Phase Modulation

Wc= 2*pi*fc;

c = Ac*cos(Wc*t);

subplot(2,2,2);

plot(t,c);

hold on

title('Carrier Signal');

xlabel('Time --->');

ylabel('Amplitude --->')

CCNA-LAB Course CECOS University of IT & Emerging Sciences Omer Mujahid©

Frequency & Phase Modulation

s_fm = Ac*cos(Wc*t+2*pi*kf*cumsum(m));

subplot(2,2,3);

plot(t,s_fm);

hold on

title('Frequency Modulated Signal');

xlabel('Time --->');

ylabel('Amplitude --->')

CCNA-LAB Course CECOS University of IT & Emerging Sciences Omer Mujahid©

Matlab Code for Frequency & Phase Modulation

s_pm = Ac*cos(Wc*t+m.*kp );

subplot(2,2,4);

plot(t,s_pm);

title('Phase Modulated Signal');

xlabel('Time --->');

ylabel('Amplitude --->')

CCNA-LAB Course CECOS University of IT & Emerging Sciences Omer Mujahid©

Results

CCNA-LAB Course CECOS University of IT & Emerging Sciences Omer Mujahid©

CCNA-LAB Course CECOS University of IT & Emerging Sciences Omer Mujahid©

CCNA-LAB Course CECOS University of IT & Emerging Sciences Omer Mujahid©

CCNA-LAB Course CECOS University of IT & Emerging Sciences Omer Mujahid©

Task

1. Perform Frequency modulation and Demodulation using simulink.

2. Use MATLAB function fmmod and fmdemod to perform Frequency modulation and demodulation.

CCNA-LAB Course CECOS University of IT & Emerging Sciences Omer Mujahid©