carrier_mod.m

使用matlab程序实现了由随机序列到码元电平、m序列直接扩频解扩、qpsk调制解调

function [y3,y4,y]=carrier_mod(f0,out1,out2)
N=20;                                  %随机数点数20
td=0.1;
f0=3000;
wc=2e4*pi;
g=100;                                 %一个矩形电平采样点

t=linspace(0,td,length(out1));
y3=(-1)*sin(2*f0*pi*t).*out1;          %I通道调制
y4=cos(2*f0*pi*t).*out2;               %Q通道调制
y=y3+y4;                               %QPSK调制

figure(4);
subplot(311);
t=linspace(0,td,length(out1));
plot(t,y3,'LineWidth',1.5);grid on;
title('I Channel Modulation');
axis([0 td -1.5 1.5]);                 %画I通道调制图
subplot(312);
plot(t,y4,'LineWidth',1.5);grid on;
title('Q Channel Modulation');
axis([0 td -1.5 1.5]);                 %画Q通道调制图
subplot(313);
plot(t,y,'LineWidth',1.5);grid on;
title('QPSK Modulation'); 
axis([0 td -1.5 1.5]);                  %画QPSK调制图