%MATLAB program 5-9
% Produce eye diagram
clear all;
clc;
% 定義所采用的進(jìn)制數(shù)和采樣率
M = 16; Fd = 1; Fs = 10; 
Pd = 100; % 計算所采用的點數(shù)
% 在[0,M-1]區(qū)間產(chǎn)生隨機整數(shù)
msg_d = randint(Pd,1,M); 
%用矩形星座QASK方法進(jìn)行調(diào)制
msg_a = modmap(msg_d,Fd,Fd,'qask',M);
%將信道近似為升余弦濾波器，且升余弦濾波器的延遲時間定為3秒
delay = 3;
rcv = rcosflt(msg_a,Fd,Fs,'fir/normal',.5,delay);
%截去升余弦濾波器輸出的尾部響應(yīng)
propdelay = delay .* Fs/Fd + 1; 
rcv1 = rcv(propdelay:end-(propdelay-1),:); 
N = Fs/Fd;
%繪出信號的眼圖并顯示出沒有偏移的情況
offset1 = 0;
h1 = eyediagram(rcv1,N,1/Fd,offset1);
set(h1,'Name','Eye Diagram Displayed with No Offset');
%繪出信號的眼圖并顯示出有偏移的情況
offset2 = 2;
h2 = eyediagram(rcv1,N,1/Fd,offset2,'r-');
set(h2,'Name','Eye Diagram Displayed with Offset of Two');