基于MATLAB实现的移相键控（PSK）中的二相移相键控（2PSK）算法+使用说明文档.rar

%%%%%%%%%%% PSK %%%%%%%%%%% clear close all clc; N=80; snr=10; n0=50; %序列长度 fc=100; %载波频率 fs=1000; %采样频率 %%%%%%%%%%% 产生随机码元 %%%%%%%%%%% X=randint(1,n0); figure(1) subplot(2,1,1);stem(X);grid; title('码元序列');xlabel('点数');ylabel('码元'); %%%%%%%%%%% 产生基带信号 %%%%%%%%%%% x=[ ]; for i=1:n0 for j=1:fs x=[x X(i)]; end end k=linspace(0,n0,n0*fs); subplot(2,1,2); plot(k,x);grid;axis([0,n0,-0.1,1.1]) title('基带信号');xlabel('点数');ylabel('基带码元'); %%%%%%%%%%% BPSK调制 %%%%%%%%%%% y1=cos(2*pi*fc*k); y2=cos(2*pi*fc*k+pi); y=[ ]; for i=1:length(x) if x(i)==1 y=[y y1(i)]; else y=[y y2(i)]; end end figure(2); plot(k,y);axis([0,n0,1.1*min(y),1.1*max(y)]); title('BPSK调制信号');xlabel('时间');ylabel('调制信号'); %%%%%%%%%%% 经过高斯白噪声的信道后的信号 %%%%%%%%%%% n=awgn(y,snr); figure(3); plot(k,n);axis([0,n0,1.1*min(n),1.1*max(n)]); title('叠加噪声信号');xlabel('时间');ylabel('信号幅值'); %%%%%%%%%%% 相乘解调 %%%%%%%%%%% p=n.*y1; figure(4); plot(k,p);axis([0,n0,1.1*min(p),1.1*max(p)]);grid; title('相干解调');xlabel('时间');ylabel('码元幅值'); %%%%%%%%%%% 低通滤波 %%%%%%%%%%% b1=fir1(N,2*fc/fs); l=filter(b1,1,p); figure(5); plot(k,l);axis([0,n0,1.1*min(l),1.1*max(l)]);grid; title('低通滤波后的接收信号');xlabel('时间');ylabel('码元幅值'); %%%%%%%%%%% 抽样判决 %%%%%%%%%%% u=[]; for i=0:n0-1 if [l(fs*i+0.3*fs)+l(fs*i+0.7*fs)]/2 > 0.2 u(i+1)=1; else u(i+1)=0; end end figure(6); stem(u);grid; title('判决信号');xlabel('时间');ylabel('码元幅值'); %%%%%%%%%%% 误码率计算 %%%%%%%%%%% disp('误码和误码率的结果显示如下：'); error=sum(abs(X-u)) error_rate=error/n0