详解MATLAB Simulink通信系统建模与仿真 随书源码-第6章数字基带传输.rar

% 有错！！！ clear all nsymbol = 100000; %每种SNR下发送的符号数 Fd = 1; %符号采样频率 Fs = 10; %滤波器采样频率 rolloff = 0.25; %滤波器滚降系数 delay = 5; %滤波器时延 M=4; %4-PAM graycode = [0 1 3 2]; EsN0 = 0:15; msg = randi([0,1],1,nsymbol); msg1 = graycode(msg+1); % Gray映射 msgmod = pammod(msg1, M); %4-PAM调制 rrcfilter = rcosine(Fd,Fs,'fir/sqrt',rolloff,delay); %设计跟升余弦滤波器 s = rcosflt(msgmod,Fd,Fs,'filter',rrcfilter); for indx=1:length(EsN0) demsg = zeros(1,nsymbol); r = awgn(real(s),EsN0(indx)-7, "measured"); rx = rcosflt(r,Fd,Fs,'filter',rrcfilter); rx1 = downsample(rx,Fs); rx2 = rx1(2*delay+1:end-2*delay); msg_demod=pamdemod(rx2,M); %判决 demsg = graycode(msg_demod+1); [err,ber(indx)] = biterr(msg,demsg,log2(M)); [err,ser(indx)] = symerr(msg,demsg); end semilogy(EsN0,ber,"-ko", EsN0, ser, "-k*", EsN0, 1.5*qfunc(sqrt(0.4*10.^(EsN0/10))), "-ro"); title("4-PAM信号在AWGN信道下的误比特率性能") xlabel("EbN0"); ylabel("误比特率P和误符号率"); legend("误比特率", "误符号率", "理论误符号率")