Vestigal side band matlab code

%>>>>>>>>>>>>>>>>>>>> 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?

How can we put frequency code here?

[dhanvanth voona]

this is only amplitude modulation, we need to design appropriate filters and apply them to message signals to obtain VSB

Answer 1

[MD Rasel Basunia]

%% message signal m(t)=u(t+2)-u(t-2)

syms t f

fc=10;%let carrier frequency frequency contain 10 Hz .x_carrier=cos(2*pi*10*t)

x = heaviside(t+2)- heaviside(t-2) %% Fourier transform of m(t)

X=fourier(x,f) ;% fourier transform

%% using anonymous function

XX = @(f) 2*(sin(2*f)./(f))

f=[-100:0.01:100-0.01];% proper frequency range .Avoiding 0 / 0.

%% Generation of DSB-SC

Xshift=( XX(f-fc)+XX(f+fc));

%% Designing VSB shaping filter characteristic

% Define normalized VSB shaping filter

Hf = @(f) ((f>=9 & f<=20)) ;

%% Generating SSB

SSB =@(f) Xshift.*(f>=10 & f<=50) + Xshift.*(f<=-10 & f>=-50);

%%Here I am just plotting SSB-SC and VSB modulation signals.you can also

%%plot Hf(f) characteristic normalized filter and DSB-SC from equation.

%% Generation of VSB

VSB_upper = @(f)((XX(f-fm)+XX(f+fm)).*Hf(f)) %SSB(f).*Hf(f)SB_upper = @(f)((XX(f-fm)+XX(f+fm)).*Hf(f)) %SSB(f).*Hf(f)

subplot(211)

%% ploting SSB

plot(f,abs(SSB(f)),[-10,-10],[0,4],[10 10],[0,4],'r','linewidth',1.5);

% set axis for visualize porpuse only

xlim([-35 35]);

grid on;ylim([0 6]);xlabel('frequency in Hz');ylabel('Magnitude spectrum');

legend('| SSB-SC|');

title('Single Sideband Modulation');

%% ploting VSB

subplot(212)

plot(f,abs(VSB_upper(f)),'b',-f,abs(VSB_upper(f)),'k','linewidth',1.5);grid on;

xlabel('frequency in Hz');ylabel('Magnitude spectrum');

title('SSB');ylim([0 6]);legend('| VSB |');

% set axis for visualize purpose

xlim([-35 35]);

% see carefully around 10 Hz .A vestige was found before +10 Hz and also in

% case negative -10 Hz