fsk_demod.m

FSK调制Matlab程序。包括FSK mod and demod；CPFSK mod and demod代码。

function [fsk_vystup]=FSK_demod(fsk_signal,fsk_signal_sum,fb,fm,N)

M = 128;
fs = 10000; 
fn = fs/2;  
f1 = fm-250; 
f2 = fm+250;
[n,Wn] = buttord([f1, f2]/fn, [f1-500, f2+500]/fn, 1, 10); 
[b,a] = butter(n,Wn);       
prefilter = filter(b,a,fsk_signal_sum); 

g   = ones(1,M);
h   = g(length(g):-1:1);
out = conv(h,abs(prefilter))/M*fb;
tmp2(1:N) = ((M-1):M:M*N);
for i = 1:N
    if (out(tmp2(i)) > sum(out)/length(out))
        vystup(i) = 0;
    else
        vystup(i) = 1;
    end
end
fsk_vystup = vystup;