how to do vestiage signal ?

%>>>>>>>>>>>>>>>>>>>> Tuterial on AM vestigial sideband 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 greater0 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 <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<

How to change this matlab code to vestigial side band?

Answer 1

[Vidhi Agarwal]

Hi @ong jia eek,

VSB is a type of amplitude modulation where one sideband is partially suppressed. This is typically done using a filter to shape the spectrum of the modulated signal. Following steps might help you in getting started:

1. Start with the standard AM signal generation.
2. Create a filter that will partially suppress one of the sidebands.
3. Use the filter to modify the AM signal, resulting in a VSB signal.

Below is the code snippet for creating and using the filter:

% VSB Modulation
% Design a simple low-pass filter to simulate VSB
% Note: For a real-world application, this filter needs to be carefully designed
f_cutoff = fc + fa/2; % Example cutoff frequency for VSB
[b, a] = butter(5, f_cutoff/(fc*10), 'low'); % 5th order Butterworth filter
 
% Apply the filter to the AM signal
y_vsb = filter(b, a, y_am);

Sample output after considering above points is given below:

Hope that Helps!