trn2.m

差分检测的程序

function [samples, demod] = trN2(z,NS)
num = 1;
T = 2;
mu = 0.01;
error(1) = 0;
strobe_early = 0;
strobe = 0;
strobe_mid = 0;
lngflt = 25;
delta = 0;
i=1:lngflt;
t(i) = (i-(lngflt+1)/2) + delta;
y_interp = sinc(t);
B = fir1(32,0.18);
I = real(z);
Q = imag(z);
clear Z;
yI = filter(B,1,I);
yQ = filter(B,1,Q);
Z = yI + yQ*j;
demod(1:NS) = imag(Z(1:NS));
demod(NS+1:length(Z)) = imag(Z(NS+1:length(Z)).*conj(Z(1:length(Z)-NS)));
xt = demod(1:NS/2:length(demod));
lngxt = length(xt);
lngy = length(y_interp);
ending = lngxt-lngy;
for n = 3:T:ending-1
strobe_early = strobe;
strobe = sum(y_interp.*xt(n:n+lngy-1));
strobe_mid = sum(y_interp.*xt(n-1:n+lngy-2));
strobes(2*num) = strobe;
strobes(2*num-1) = strobe_mid;
error(num) = (sign(strobe)-sign(strobe_early))*(strobe_mid);
delta = error(num)*0.1 + delta;
phase(num) = delta;
t(i) = (i-(lngflt+1)/2) + delta;
y_interp = sinc(t);
samples(num) = (strobe >0)*2-1;
num = num+1;
end