【数字信号调制】基于matlab多进制数字相位调制（4PSK）【含Matlab源码 1001期】.zip

%4PSK解调与解调 %假设在T=1,加入高斯噪声 clear all close all % 调制 bit_in = randint(1e3, 1, [0 1]); bit_I = bit_in(1:2:1e3); bit_Q = bit_in(2:2:1e3); data_I = -2*bit_I+1; data_Q = -2*bit_Q+1; data_I1=repmat(data_I',20,1); data_Q1=repmat(data_Q',20,1); for i=1:1e4 data_I2(i)=data_I1(i); data_Q2(i)=data_Q1(i); end; f=0:0.1:1; xrc=0.5+0.5*cos(pi*f); data_I2_rc=conv(data_I2,xrc)/5.5; data_Q2_rc=conv(data_Q2,xrc)/5.5; f1=1; t1=0:0.1:1e3+0.9; n0=rand(size(t1)); I_rc=data_I2_rc.*cos(2*pi*f1*t1); Q_rc=data_Q2_rc.*sin(2*pi*f1*t1); QPSK_rc=(sqrt(1/2).*I_rc+sqrt(1/2).*Q_rc); QPSK_rc_n0=QPSK_rc+n0; % 解调 I_demo=QPSK_rc_n0.*cos(2*pi*f1*t1); Q_demo=QPSK_rc_n0.*sin(2*pi*f1*t1); % 低通滤波 I_recover=conv(I_demo,xrc); Q_recover=conv(Q_demo,xrc); I=I_recover(11:10010); Q=Q_recover(11:10010); t2=0:0.05:1e3-0.05; t3=0:0.1:1e3-0.1; % 抽样判决 data_recover=[]; for i=1:20:10000 data_recover=[data_recover I(i:1:i+19) Q(i:1:i+19)]; end; bit_recover=[]; for i=1:20:20000 if sum(data_recover(i:i+19))>0 data_recover_a(i:i+19)=1; bit_recover=[bit_recover 1]; else data_recover_a(i:i+19)=-1; bit_recover=[bit_recover -1]; end end error=0; dd = -2*bit_in+1; ddd=[dd']; ddd1=repmat(ddd,20,1); for i=1:2e4 ddd2(i)=ddd1(i); end figure(1) subplot(4,1,1);plot(t2,ddd2);axis([0 10 -2 2]);title('输入序列'); subplot(4,1,2);plot(t1,QPSK_rc);axis([0 10 -2 2]);title('QPSK信号'); subplot(4,1,3);plot(t1,QPSK_rc_n0);axis([0 10 -2 2]);title('加入噪声的QPSK信号'); subplot(4,1,4);plot(t2,data_recover_a);axis([0 10 -2 2]);title('解调后输出序列');