m=64;
N=256;
n=1:1:N;
N0=0.3*rand(1,N)-0.15; %高斯隨機噪聲

a=rand(1,m);%產生隨機序列，與4PSK是1：4的數量關系
for i=1:m
    if(a(1,i)<0.25)
        a(1,i)=1;
    else
        if(a(1,i)<0.5)
            a(1,i)=3;
        else
            if(a(1,i)<0.75)
                a(1,i)=5;
            else
                a(1,i)=7;
            end;
        end;
    end;
end;

X_4psk=zeros(1,N);%4PSK調制

j=1;k=1;
for i=1:N
    if(j==(N/m+1))
        j=1;
        k=k+1;
    end;
    X_4psk(1,i)=1.414*sin(2*pi*0.25*i+a(1,k)*pi/4+0.2*pi);
    j=j+1;
end;
X_4psk=X_4psk+N0;%調制后加噪聲

X_4psk_m1=X_4psk.*sin(2*pi*0.25*n+0.15*pi);%SIN分量
X_4psk_m2=X_4psk.*sin(2*pi*0.25*n+0.65*pi);%COS分量