新建文本文档.txt

产生一个在某一区域内的随机整数序列

均衡器Matlab例程(1)解析 
Equalizing Using a Training Sequence 

例程代码 
% Set up parameters and signals. 
M = 4; % Alphabet size for modulation 
msg = randint(1500,1,M); % Random message，产生一个1500 x 1 在[0，M-1]区域内的随机整数序列 
modmsg = pskmod(msg,M); % Modulate using QPSK. 进行QPSK调制的映射 
trainlen = 500; % Length of training sequence 定义训练序列的帧长 
chan = [.986; .845; .237; .123+.31i]; % Channel coefficients 定义信道参量 
filtmsg = filter(chan,1,modmsg); % Introduce channel distortion. 模拟信道变化 
% Equalize the received signal. 
eq1 = lineareq(8, lms(0.01)); % Create an equalizer object. 
eq1.SigConst = pskmod([0:M-1],M); % Set signal constellation. 设置星座图 
[symbolest,yd] = equalize(eq1,filtmsg,modmsg(1:trainlen)); % Equalize. 
% Plot signals. 
h = scatterplot(filtmsg,1,trainlen,'bx'); hold on; 以蓝星画出未经过均衡的信号 
scatterplot(symbolest,1,trainlen,'g.',h); 在原图的基础上以绿色画出经过均衡后的信号 
scatterplot(eq1.SigConst,1,0,'k*',h); 在原图的基础上以黄色标出理想星座图 
legend('Filtered signal','Equalized signal',... 
'Ideal signal constellation'); 
hold off; 
% Compute error rates with and without equalization. 计算误码率 
demodmsg_noeq = pskdemod(filtmsg,M); % Demodulate unequalized signal. 解调未均衡的码字 
demodmsg = pskdemod(yd,M); % Demodulate detected signal from equalizer.解调已均衡的码字 
[nnoeq,rnoeq] = symerr(demodmsg_noeq(trainlen+1:end),...对比未均衡信号和样本信号的误码和误码率 
msg(trainlen+1:end)); 
[neq,req] = symerr(demodmsg(trainlen+1:end),... 
msg(trainlen+1:end)); 对比均衡信号和样本信号的误码和误码率 
disp('Symbol error rates with and without equalizer:') 
disp([req rnoeq]