未命名文件夹 2.zip_M-QAM_matlab_qam_调制信号qam

clear all M=4; k=log2(M); N=200; samp=1;%采样率 x=randi([0,1],N,1);%产生伪随机二进制作为输入数据 stem(x,'filled'); title('二进制随机比特流'); xlabel('比特序列'); ylabel('信号幅度'); x4=reshape(x,k,length(x)/k);%将原始二进制数转为2个一组 xsym=bi2de(x4.','left-msb');%将矩阵转为相应的16进制信号序列 figure; stem(xsym); title('4进制随机信号'); xlabel('信号序列'); ylabel('信号幅度'); y=modulate(modem.qammod(M),xsym)/sqrt(2);%使用16QAM调制器对信号进行调制 scatterplot(y); hold on; % text(real(y)+0.1,imag(y),dec2bin(xsym)); axis([-1 1 -1 1]); % EbNo=15;%假设Eb/No=15db % SNR=EbNo+10*log(k)-10*log10(samp); SNR=20; yn=awgn(y,SNR,'measured'); h=scatterplot(yn,samp,0,'b.'); hold on; scatterplot(y,1,0,'r+',h); title('接收信号星座图'); % legend('含噪声接收信号','不含噪声信号');