gaosi.m

Tdscdma系统中的载频估计程序

clear;
echo off;
fc=3e3;                                   %%%%%%%%%    载波频差4kHz
% fi=16e3;                                %%%%%%%%%    频谱搬移16k
mc=1.28e6;                                %%%%%%%%%    码片速率1.28M
nc=4;                                     %%%%%%%%%    采样不加内插，每码片4采样
fs=nc*mc;                                 %%%%%%%%%    1/fs 为采样间隔
ts=1/fs;
sg=1;                                     %%%%%%%%%    噪声能量归一化
snr=1:25;
Nb=500;
for k=1:length(snr)
   eb=10^(snr(k)/10)*2;
amp=sqrt(2*eb/16);
N =144*nc;
fai=rand;
for r=1:Nb
%     nois=sg.*randn(1,N);
com_noi  = sqrt(sg).*(randn(1,N)+j.*randn(1,N));
n=0:N-1;
re=amp*(1+j)*exp(-j*2*pi*(fc*n*ts+fai))+com_noi;
for i=1:N-1
    D(i)=conj(re(i))*re(i+1);
end
D2=sum(D);
DQ=real(D2);
DI=imag(D2);
fe(r)=-(tan(DI/DQ))/(2*pi*ts);
end
fk(k)=sum(fe)/Nb;
fangcha(k)=sqrt(var(fe));
end
plot(fk)
xlabel('snr input (DB)');
ylabel('carrier offset (Hz)');
figure(2)
x=(1:25);
bar(x,fangcha)
xlabel('snr input (DB)');
ylabel(' variance of estimated value (Hz)');