WJMatlab-QPSK Coding Scehma

QPSK.m

// QPSK Program
clc;
clear all;
close all;

xSignal = [ 1 0 0 1 1 0 1 0 1 1 ];
bitPeriod = 0.000001;
Amplitude = 5;
bitRate = 1/bitPeriod;
frequency = bitRate;

% Data Signal Plot
FigHandle = figure('Position', [300, 100, 800, 800]);
subplot(5, 1, 1);
stem(xSignal, 'linewidth',3), grid on;
title('Information Before Transmiting ');
axis([ 0 11 0 1.5]);
nzrSignal = 2*xSignal-1;
spSignal = reshape(nzrSignal,2,length(xSignal)/2);
table = bitPeriod/99 : bitPeriod/99 : bitPeriod;

% QPSK Modulation Plot
y = [];
inphaseSignal = [];
quadratureSignal = [];
for i = 1 : length(xSignal)/2
    y1 = spSignal(1,i)*cos(2*pi*frequency*table);
    y2 = spSignal(2,i)*sin(2*pi*frequency*table);
    inphaseSignal = [inphaseSignal y1];
    quadratureSignal = [quadratureSignal y2];
    y = [y y1+y2];
end
transmittingSignal = y;
table2 = bitPeriod/99 : bitPeriod/99 : (bitPeriod*length(xSignal))/2;

subplot(5, 1, 2);
plot(table2,inphaseSignal,'linewidth',3), grid on;
title('Inphase QPSK Modulation ');
xlabel('T(sec)');
ylabel('A(volt0');

subplot(5, 1, 3);
plot(table2,quadratureSignal,'linewidth',3), grid on;
title('Quadrature QPSK Modulation ');
xlabel('T(sec)');
ylabel('A(volt0');

subplot(5, 1, 4);
plot(table2,transmittingSignal,'r','linewidth',3), grid on;
title('QPSK Modulated Signal (Sum of Inphase and Quadrature Phase Signal)');
xlabel('T(sec)');
ylabel('A(volt0');

% QPSK Demodulation Plot
receivedData = [];
receivedSignal = transmittingSignal;
for i = 1 : 1 : length(xSignal)/2
    inphaseDector = receivedSignal((i-1)*length(table)+1 : i*length(table)).*cos(2*pi*frequency*table); 
    inphaseDectorIntegrated=(trapz(table,inphaseDector))*(2/bitPeriod);
    if inphaseDectorIntegrated > 0
        receivedInphaseData = 1;
    else
       receivedInphaseData = 0; 
    end
    quadratureDector = receivedSignal((i-1)*length(table)+1:i*length(table)).*sin(2*pi*frequency*table);    
    quadratureDectorIntegrated = (trapz(table,quadratureDector))*(2/bitPeriod);
    if quadratureDectorIntegrated > 0
        receivedQuadratureData = 1;
    else
        receivedQuadratureData = 0; 
    end        
    receivedData = [receivedData  receivedInphaseData  receivedQuadratureData];
end

subplot(5, 1, 5);
stem(receivedData,'linewidth',3) 
title('Information After Receiveing ');
axis([ 0 11 0 1.5]), grid on;