QPSK信号的星座圖

• 基本原理
• • 源代碼
  • • 仿真結果

基本原理

源代碼

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%             QPSK的星座圖
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

clc;
clear all; 
close all;

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%               參數設定
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Qm=2;    % 定義每符号的比特數
N=1e3;   % 符号數
SNR=20;  % 信噪比 dB


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%                 信源
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
d1=2*randi([0,1],1,N)-1; % 随機産生同向、正交兩個方向的比特值
d2=2*randi([0,1],1,N)-1;
s=d1+1i*d2;              % 得到複信号  QPSK信号

E=s*s';
% fprintf('信号的功率為%g\n',E);

scatterplot(s);grid on;
title('未加噪的QPSK信号星座圖');


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%         信道（高斯白噪聲）
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
noise=randn(size(s))+1j*randn(size(s));  % 複噪聲
E1=noise*noise';
% fprintf('噪聲的功率為%g\n',E1);

y=sqrt(10^(SNR/10))*s+noise;   %對複信号加複噪聲
scatterplot(y);grid on;
title('加噪QPSK信号的星座圖');



           

仿真結果