Modulace BPSK
%% BPSK
% Tomas Krejci, 11.4.2015
clc
close all
clear all
data = [1 1 0 1 0 0 0 1 1 1];
% = randi([0 1], n_data, 1)
%% BPSK
fs = 100E6;
Ts = 10E-6; % interval symbolu
n_data = length(data);
Tr = n_data * Ts; % delka celeho signalu
nn = fs*Ts; % pocet vzorku v symbolovem intervalu
t = 0 : 1/fs : Tr - 1/fs;
y_c = zeros(1, nn * n_data);
y_s = zeros(1, nn * n_data);
for ii = 1 : n_data
if data(ii) == 0
y_c((ii-1)*nn+1 : ii*nn ) = 1;
y_s((ii-1)*nn+1 : ii*nn ) = 1;
else
y_c((ii-1)*nn+1 : ii*nn ) = -1;
y_s((ii-1)*nn+1 : ii*nn ) = -1;
end
end
f = 1E6; % frekvence nosne
s = y_c .* cos(2*pi*f*t) + y_s .* sin(2*pi*f*t); % vysledny signal
S= 10*log10((abs(fftshift(fft(s)))).^2);% energetické spektrum signálu
fx = fs/2 * linspace(-1,1,length(s));
figure;
subplot(2,1,1); plot(t,s); title('BPSK'); xlabel('t [s]'); ylabel('A [V]');
subplot(2,1,2); plot(fx,S); title('Spektrum');xlabel('f [Hz]'); ylabel('Se [dB]');
ylim([-20 max(S)*1.2 ]); xlim([-3E6 3E6]);
Modulace QPSK
%% QPSK
% Tomas Krejci, 11.4.2015
clc
close all
clear all
data = [1 1 0 1 0 0 0 1 1 1];
fs = 100E6;
Ts = 10E-6; % interval symbolu
Nb = 2; % Q=4 -> 4=2^2
n_data = length(data);
Tr = n_data/Nb * Ts; % delka celeho signalu
nn = fs*Ts; % pocet vzorku v symbolovem intervalu
t = 0 : 1/fs : Tr - 1/fs;
y_c = zeros(1, nn * n_data/Nb);
y_s = zeros(1, nn * n_data/Nb);
jj = 1;
for ii = 1 : Nb : n_data-1
if data(ii)==0 && data(ii+1)==0
y_c( (jj-1)*nn+1 : jj*nn ) = 0.5;
y_s( (jj-1)*nn+1 : jj*nn ) = 0.5;
end
if data(ii)==0 && data(ii+1)==1
y_c( (jj-1)*nn+1 : jj*nn ) = -0.5;
y_s( (jj-1)*nn+1 : jj*nn ) = 0.5;
end
if data(ii)==1 && data(ii+1)==0
y_c( (jj-1)*nn+1 : jj*nn ) = -0.5;
y_s( (jj-1)*nn+1 : jj*nn ) = -0.5;
end
if data(ii)==1 && data(ii+1)==1
y_c( (jj-1)*nn+1 : jj*nn ) = 0.5;
y_s( (jj-1)*nn+1 : jj*nn ) = -0.5;
end
jj = jj + 1;
end
f = 1E6; % f nosne
s = y_c .* cos(2*pi*f*t) + y_s .* sin(2*pi*f*t); % vysledny signal
S= 10*log10((abs(fftshift(fft(s)))).^2);% energetické spektrum signálu
fx = fs/2 * linspace(-1,1,length(s));
figure;
subplot(2,1,1); plot(t,s); title('QPSK'); xlabel('t [s]'); ylabel('A [V]');
subplot(2,1,2); plot(fx,S); title('Spektrum');xlabel('f [Hz]'); ylabel('Se [dB]');
ylim([-20 max(S)*1.2 ]); xlim([-3E6 3E6]);</pre>
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