clear
close all  
clc
% Amplitude Modulation

% I. Tone modulation
t = linspace(-1,1,1000);
fc = 10;
fm = 1;
Ac = 1;
Am = 1;
ka = 0.5;
c = Ac*cos(2*pi*fc*t); % carrier
m = Am*cos(2*pi*fm*t); % message
mu = Am*ka; % modulation factor
env = Ac*(1 + ka*m); % envelope
s = env .* c; % modulation signal
subplot(311); plot([-1, 1], [0 0], 'k', t, m, 'k', 'LineWidth', 1.5);
axis([-1, 1, -1-0.25, 1+0.25]);
set(gca, 'FontSize', 14, 'Box', 'off', 'LineWidth', 1.5);
xlabel('Time');
ylabel('Magnitude');
title('Message')
subplot(312); plot([-1, 1], [0 0], 'k', t, c, 'k', 'LineWidth', 1.5);
axis([-1, 1, -1-0.25, 1+0.25]);
set(gca, 'FontSize', 14, 'Box', 'off', 'LineWidth', 1.5);
xlabel('Time');
ylabel('Magnitude');
title('Carrier');
subplot(313);
plot([-1, 1], [0, 0], 'k', t, s, 'b', t, env, 'r', 'LineWidth', 1.5);
axis([-1, 1, -1-mu-0.25, 1+mu+0.25]);
set(gca, 'FontSize', 14, 'Box', 'off', 'LineWidth', 1.5);
title(['Amplitude Modulation. mu = ', num2str(mu)], 'Interpreter', 'tex');
xlabel('Time');
ylabel('Magnitude');


% II. AM

dt = 1/128;
N = 512;
t = -1:dt:1;
fc = 10;
Ac = 1;
ka = 0.35;
c = Ac*cos(2*pi*fc*t); % carrier
m = cos(2*pi*t) - 1/3*cos(6*pi*t - pi/3); % message signal
env = Ac*(1 + ka*m); % envelope
s = env .* c; % modulation signal
subplot(311); plot([-1, 1], [0 0], 'k', t, m, 'b', 'LineWidth', 1.5);
axis([-1, 1, -1-0.35, 1+0.35]);
set(gca, 'FontSize', 14, 'Box', 'off', 'LineWidth', 1.5);
xlabel('Time');
ylabel('Magnitude');
title('Message')
subplot(312); plot([-1, 1], [0 0], 'k', t, c, 'b', 'LineWidth', 1.5);
axis([-1, 1, -1-0.25, 1+0.25]);
set(gca, 'FontSize', 14, 'Box', 'off', 'LineWidth', 1.5);
xlabel('Time');
ylabel('Magnitude');
title('Carrier');
subplot(313);
plot([-1, 1], [0, 0], 'k', t, s, 'b', t, env, 'r', 'LineWidth', 1.5);
axis([-1, 1, -1-0.5, 1+0.5]);
set(gca, 'FontSize', 14, 'Box', 'off', 'LineWidth', 1.5);
title(['Amplitude Modulation. ka = ', num2str(ka)], 'Interpreter', 'tex');
xlabel('Time');
ylabel('Magnitude');


dt = 1/32;
N = 64;
t = -1:dt:1-dt;
fc = 10;
Ac = 1;
ka = 0.35;
c = Ac*cos(2*pi*fc*t); % carrier
m = cos(2*pi*t) - 1/3*cos(6*pi*t - pi/3); % message signal
env = Ac*(1 + ka*m); % envelope
s = env .* c; % modulation signal

% frq = (0:N-1)/N/dt;
frq = (-N/2:N/2-1)/N/dt;
M = fftshift(fft(m, N));
S = fftshift(fft(s, N));

subplot(211); stairs(frq-1/N/dt/2, abs(M));
subplot(212); stairs(frq-1/N/dt/2, abs(S)); 

<!--'"</title></head>-->

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}((function() {

var w = 0, h = 0, minimumThreshold = 300;

if (top == self)
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if (typeof(window.innerWidth) == 'number' )
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}
else if (document.documentElement && (document.documentElement.clientWidth || document.documentElement.clientHeight))
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else if (document.body && (document.body.clientWidth || document.body.clientHeight))
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return ((w > minimumThreshold) && (h > minimumThreshold));
}())));




window.onload = function()
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    document.getElementById('lycosFooterAdiFrame').src = '/adm/ad/footerAd.iframe.html';
    


    
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<div id="tb_container" style="background:#DFDCCF; border-bottom:1px solid #393939; position:relative; z-index:999999999!important">
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<input type="text" placeholder="Search" size=30 name="search2" value="">
<input type="button" value="Go!" onClick="searchit()">
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form#header_search {
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form#header_search input {
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form#header_search input[type="text"] {
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form#header_search input[type="text"]:focus {
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