clear;
load c;
Fs=38400;    %WCDMA信號(hào)的采樣率
nsamp=16;    %過采樣率
delay=3;    %根號(hào)下升余弦的群時(shí)延
datain=c;   %這里c為WCDMA系統(tǒng)的擾碼數(shù)據(jù)
Num=length(datain);  %計(jì)算相關(guān)的長(zhǎng)度
 
dataout=RRCsend(datain,Fs,nsamp,delay); %調(diào)用子程序，經(jīng)過發(fā)送端的根號(hào)下升余弦濾波，輸入采樣率為1，輸出采樣率為16
 
%經(jīng)過AWGN信道
SNR_DB=-22;  %信噪比
snr=10^(SNR_DB/10);
noise_var = 2/snr;   %假設(shè)dataout的平均碼片能量為2
noise = sqrt(1/2*noise_var)*(randn(1,length(dataout))+j*randn(1,length(dataout)));
datachannel=dataout+noise;   %加噪聲

datarece=RRCrece(datachannel,Fs,nsamp,delay,1);% 調(diào)用子程序，收端的根號(hào)下升余弦匹配濾波器，輸入輸出的采樣率都為16倍
optimal_sample_piont=1+2*delay*nsamp;   %最佳采樣點(diǎn)的起始位置
dataext=[datain,datain,datain];   %用于接收端相關(guān)的擾碼
 
%設(shè)計(jì)低通濾波器
[b,a] = cheby2(3,20,100/19200);  %3階，帶外衰減20dB，采用率38400Hz，低通帶寬100Hz
%偏離最佳采樣點(diǎn)，向前偏移
for ii=1:16
datasample=datarece(optimal_sample_piont-16+ii:16:length(datarece)-2*delay*nsamp-15);
temp=real(datasample).*real(dataext(Num:2*Num-1))+imag(datasample).*imag(dataext(Num:2*Num-1));
    temp=filter(b,a,temp);%經(jīng)過低通濾波器
    val_co1=sum(temp);%早門支路相關(guān)
temp=real(datasample).*real(dataext(Num+2:2*Num+1))+imag(datasample).*imag(dataext(Num+2:2*Num+1));
    temp=filter(b,a,temp);% 經(jīng)過低通濾波器
val_co2=sum(temp);% 遲門支路相關(guān)   
val_co(ii)=(val_co2-val_co1)/(2*Num);%計(jì)算兩路相關(guān)的差值，并歸一化
end;
%偏離最佳采樣點(diǎn)，向后偏移 
for ii=1:15
datasample=datarece(optimal_sample_piont+ii:16:length(datarece)-2*delay*nsamp+1); temp=real(datasample).*real(dataext(Num:2*Num-1))+imag(datasample).*imag(dataext(Num:2*Num-1));
    temp=filter(b,a,temp);%經(jīng)過低通濾波器
    val_co1=sum(temp);%早門支路相關(guān)
temp=real(datasample).*real(dataext(Num+2:2*Num+1))+imag(datasample).*imag(dataext(Num+2:2*Num+1));
    temp=filter(b,a,temp);% 經(jīng)過低通濾波器
    val_co2=sum(temp);%遲門支路相關(guān)
    val_co(16+ii)=(val_co2-val_co1)/(2*Num);% 計(jì)算兩路相關(guān)的差值，并歸一化
end;
 
ii=-15:15;
figure
stem(ii,val_co);
xlabel('采樣點(diǎn)偏移');
ylabel('歸一化相關(guān)點(diǎn)');