基于matlab的2PSK系统的课程设计报告

表示第n个符号的绝对相位：elseg(n)==1;B=ones(1,200);c=cos(f*t+pi);%载波信号endcm=[cmB];%s(t),码元宽度200mod=[modc];%与s(t)等长的载波信号endtiaoz=cm.*mod;%e(t)调制figure(1);subplot(4,2,2);plot(tiaoz);gridon;axis([0200*length(g)-22]);title('2PSK调制信号');figure(2);subplot(4,2,1);plot(abs(fft(cp)));axis([0200*length(g)0400]);title('原始信号频谱');figure(2);subplot(4,2,2);plot(abs(fft(tiaoz)));axis([0200*length(g)0400]);title('2PSK信号频谱');%带有高斯白噪声的信道tz=awgn(tiaoz,10);%信号tiaoz中加入白噪声，信噪比为10figure(1);subplot(4,2,3);plot(tz);gridonaxis([0200*length(g)-22]);title('通过高斯白噪声信道后的信号');figure(2);subplot(4,2,3);plot(abs(fft(tz)));axis([0200*length(g)0400]);title('加入白噪声的2PSK信号频谱');jiet=2*mod1.*tz;%同步解调figure(1);subplot(4,2,4);plot(jiet);gridonaxis([0200*length(g)-22]);title('相乘后信号波形')figure(2);subplot(4,2,4);plot(abs(fft(jiet)));axis([0200*length(g)0400]);title('相乘后信号频谱');%低通滤波器fp=500;fs=700;rp=3;rs=20;fn=11025;ws=fs/(fn/2);wp=fp/(fn/2);%计算归一化角频率[n,wn]=buttord(wp,ws,rp,rs);%计算阶数和截止频率[b,a]=butter(n,wn);%计算H(z）figure(4);freqz(b,a,1000,11025);subplot(2,1,1);axis([04000-1003])title('LPF幅频相频图');jt=filter(b,a,jiet);figure(1);subplot(4,2,5);plot(jt);gridonaxis([0200*length(g)-22]);title('经低通滤波器后信号波形')figure(2);subplot(4,2,5);plot(abs(fft(jt)));axis([0200*length(g)0400]);title('经低通滤波器后信号频谱');%抽样判决form=1:200*length(g);ifjt(m)<0;jt(m)=1;elsejt(m)>=0;jt(m)=0;endendfigure(1);subplot(4,2,6);plot(jt);gridonaxis([0200*length(g)-22]);title('经抽样判决后信号s^(t)波形')figure(2);sub