# Time scaling matlab code

77 views (last 30 days)
ong jia eek on 15 Oct 2019
Edited: Sk Group on 25 Oct 2021
%>>>>>>>>>>>>>>>>>>>> Tuterial on AM Modulation <<<<<<<<<<<<<<<<<<<<<<<<<<
clc;
close all;
clear all;
%XXXXXXXXXXXXXXXXXXXXXXXXXXX Define AM modulation Index XXXXXXXXXXXXXXXXXXX
disp(' example: m=1 means 100% modulation');
m=input(' Enter the value of modulation index (m) = ');
%m=1; % for 100% modulation
if (0>m||m>1)
error('m may be less than or equal to one and geter than to zero');
end
%XXXXXXXXXXXXXXXXX modulating signal generation XXXXXXXXXXXXXXXXXXXXXXXXXX
Am =input('Enter the value of amplitude modulation =');
%Am=5; % Amplitude of modulating signal
fa=2000; % Frequency of modulating signal
Ta=1/fa; % Time period of modulating signal
t=0:Ta/999:6*Ta; % Total time for simulation
ym=Am*sin(2*pi*fa*t); % Equation of modulating signal
figure(1)
subplot(3,1,1);
plot(t,ym), grid on;% Graphical representation of Modulating signal
%axis ([0 1 -5 5]);
title ( ' Modulating Signal ');
xlabel ( ' time(sec) ');
ylabel (' Amplitud(volt) ');
%XXXXXXXXXXXXXXXXXXXXX carrier signal generation XXXXXXXXXXXXXXXXXXXXXXXXXX
Ac=Am/m;% Amplitude of carrier signal [ where, modulation Index (m)=Am/Ac ]
fc=fa*10;% Frequency of carrier signal
Tc=1/fc;% Time period of carrier signal
yc=Ac*sin(2*pi*fc*t);% Eqation of carrier signal
subplot(3,1,2);
plot(t,yc), grid on;% Graphical representation of carrier signal
title ( ' Carrier Signal ');
xlabel ( ' time(sec) ');
ylabel (' Amplitud(volt) ');
%XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX AM Modulation XXXXXXXXXXXXXXXXXXXXXXXXXXXXX
y=Ac*(1+m*sin(2*pi*fa*t)).*sin(2*pi*fc*t); % Equation of Amplitude
%modulated signal
subplot(3,1,3);
plot(t,y);% Graphical representation of AM signal
title ( ' Amplitude Modulated signal ');
xlabel ( ' time(sec) ');
ylabel (' Amplitud(volt) ');
grid on;
%>>>>>>>>>>>>>>>>>>>>>> end of program <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
Question
How to do time scaling in the full AM modulation?
KALYAN ACHARJYA on 15 Oct 2019
Edited: KALYAN ACHARJYA on 15 Oct 2019
example: m=1 means 100% modulation
Enter the value of modulation index (m) = 0.2
Enter the value of amplitude modulation =4
Where is 2 cycle?

Neeraj Kaberpanthi on 16 Oct 2019
Edited: Neeraj Kaberpanthi on 16 Oct 2019
Hi,
I have added a new variable 'n' for the number of cycles required @ line number 14 and used it @ line number 18.
%>>>>>>>>>>>>>>>>>>>> Tuterial on AM Modulation <<<<<<<<<<<<<<<<<<<<<<<<<<
clc;
close all;
clear all;
%XXXXXXXXXXXXXXXXXXXXXXXXXXX Define AM modulation Index XXXXXXXXXXXXXXXXXXX
disp(' example: m=1 means 100% modulation');
m=input(' Enter the value of modulation index (m) = ');
%m=1; % for 100% modulation
if (0>m||m>1)
error('m may be less than or equal to one and geter than to zero');
end
%XXXXXXXXXXXXXXXXX modulating signal generation XXXXXXXXXXXXXXXXXXXXXXXXXX
Am =input('Enter the value of amplitude modulation =');
n=input('Enter number of cycles = '); % input for number of modulationd signal cycles
%Am=5; % Amplitude of modulating signal
fa=2000; % Frequency of modulating signal
Ta=1/fa; % Time period of modulating signal
t=0:Ta/999:n*Ta; % Total time for simulation
ym=Am*sin(2*pi*fa*t); % Equation of modulating signal
figure(1)
subplot(3,1,1);
plot(t,ym), grid on;% Graphical representation of Modulating signal
%axis ([0 1 -5 5]);
title ( ' Modulating Signal ');
xlabel ( ' time(sec) ');
ylabel (' Amplitud(volt) ');
%XXXXXXXXXXXXXXXXXXXXX carrier signal generation XXXXXXXXXXXXXXXXXXXXXXXXXX
Ac=Am/m;% Amplitude of carrier signal [ where, modulation Index (m)=Am/Ac ]
fc=fa*10;% Frequency of carrier signal
Tc=1/fc;% Time period of carrier signal
yc=Ac*sin(2*pi*fc*t);% Eqation of carrier signal
subplot(3,1,2);
plot(t,yc), grid on;% Graphical representation of carrier signal
title ( ' Carrier Signal ');
xlabel ( ' time(sec) ');
ylabel (' Amplitud(volt) ');
%XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX AM Modulation XXXXXXXXXXXXXXXXXXXXXXXXXXXXX
y=Ac*(1+m*sin(2*pi*fa*t)).*sin(2*pi*fc*t); % Equation of Amplitude
%modulated signal
subplot(3,1,3);
plot(t,y);% Graphical representation of AM signal
title ( ' Amplitude Modulated signal ');
xlabel ( ' time(sec) ');
ylabel (' Amplitud(volt) ');
grid on;
%>>>>>>>>>>>>>>>>>>>>>> end of program <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
--------------------------------------------- Output----------------------------------
example: m=1 means 100% modulation
Enter the value of modulation index (m) = 0.5
Enter the value of amplitude modulation =1
Enter number of cycles = 2
##### 2 CommentsShowHide 1 older comment
Walter Roberson on 3 Feb 2021
That code does not do time scaling at all, and it contains several useless statements in it.

Sk Group on 8 Feb 2021
Edited: Sk Group on 25 Oct 2021

### Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by