filer_qpsk3q.m

cdma 系统级仿真

%升余弦滤波器+PSK调制,%已生成QPSK和OQPSK信号
function y=filer_QPSK3q(a,b)%
%生成随机数
Rb=800000;%码元速率819.2k
k=1;                %一个码元间隔包括1个载波周期
k2=8;
fc=k*Rb;                             %  载波频率，
fs=fc*k2;                             %  信号采样率
x_size=k*k2;
x_i=a;
x_q=b;
x_length=length(x_i(1,:));
channel=2;
for var=1:channel
    %基带滤波
    filtout_I(var,:)= rcosflt(x_i(var,:),1,x_size,'fir',0.2);%利用现成的升余弦函数
    filtout_Q(var,:)= rcosflt(x_q(var,:),1,x_size,'fir',0.2);
    filtoutI(var,:)=filtout_I(var,2.5*x_size+1:x_length*x_size+2.5*x_size);
    filtoutQ(var,:)=filtout_Q(var,2.5*x_size+1:x_length*x_size+2.5*x_size);
    %将i路提前半个码元，相当于将q路延迟半个码元
    filtoutforeI(var,:)=zeros(1,length(filtoutI(var,:)));
    filtoutforeI(var,1:length(filtoutI)-x_size/2)=filtoutI(var,x_size/2+1:length(filtoutI));
    %产生载波
    carry_i(1:x_length*x_size)=cos(2*pi*fc*(1:x_length*x_size)/fs+pi/4); 
    carry_q(1:x_length*x_size)=sin(2*pi*fc*(1:x_length*x_size)/fs+pi/4); 
    %BPSK调制
    s_q(var,:)=filtoutQ(var,:).*carry_q;
    sfore_i(var,:)=filtoutforeI(var,:).*carry_i;
    soqpsk(var,:)=sfore_i(var,:)+s_q(var,:);
end
y=sum(soqpsk);
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% fft_filtoutI=abs(fft(filtoutQ));             
% fft_soqpsk=abs(fft(soqpsk));             
% n=size(soqpsk,2);%FFT后数据点数目,d = size(X)返回二维向量，分别为矩阵X行数和列数
% f=1:fs/n:fs;
% m=fc/fs*n*2;       %此处m=fs/4=2fc
%  %图1,调制信号频谱图
% figure(1)
% subplot(2,1,1)
% plot(f(1,1:m),fft_soqpsk(1,1:m))
% title('调制信号频谱')
% grid on
% subplot(2,1,2)
% plot(f(1,1:m),fft_filtoutI(1,1:m))
% title('基带信号频谱')
% grid on
% 
% 
% figure(2)
% subplot(3,1,1)
% plot(filtoutforeI(1:20*x_size))                   
% grid on
% title('I路码元信号')
% 
% subplot(3,1,2)
% plot(filtoutQ(1:20*x_size))         
% title('Q路码元信号')
% grid on
% subplot(3,1,3)
% plot(carry_i(1:20*x_size))               %显示调制信号波形
% title('载波')
% grid on
% 
% figure(4)
% subplot(3,1,1)
% plot(sfore_i(1:20*x_size))                   %显示基带信号波形
% grid on
% title('I路BPSK调制信号')
% subplot(3,1,2)
% plot(s_q(1:20*x_size))          %显示载波信号波形
% title('Q路BPSK调制信号')
% grid on
% subplot(3,1,3)
% plot(soqpsk(1:20*x_size))               %显示调制信号波形
% title('OQPSK调制信号')
% grid on