ch10_02.m

《Matlab7.x系统建模与仿真》光盘源码

clear all;
clc;
%设置调制信号的抽样间隔
xSampleTime = 1/100000;
%设置仿真时间长度
xSimulationTime = 10;
%设置随机数产生器的初始化种子
xInitialSeed = [61 71];
%设置QPSK调制的初始相位
xPhaseOffset = pi/4;

%x表示信噪比的取值范围
x = 0:1;
%y表示QPSK调制的误符号率
y = x;

hold off;
for index = 1:4
    %设置QPSK调制信号的抽样个数
    xSamplesPerSymbol = index;
    %设置绘图颜色和误码率计算模块的接收矩阵
    %当xSamplePerSymbol不等于1时误码率计算模块有一个符号的接收时延
    switch index
        case 1
            xReceiveDelay = 0;
            color = 'r';
        case 2
            xReceiveDelay = 1;
            color = 'g';
        case 3
            xReceiveDelay = 1;
            color = 'b';
        case 4
            xReceiveDelay = 1;
            color = 'm';
    end
    for i = 1:length(x)
        %信噪比依次取向量x的数值
        xSNR = x(i);
        %执行QPSK仿真模型
        sim('ch1003');
        %从xErrorRate中获得调制信号的误码率
        y(index,i) = xErrorRate(1);
    end
    %绘制信噪比与误码率的关系曲线
    semilogy(x,y(index,:),color);
    hold on;
end