www.pudn.com > PSK.zip > my_pskdemod.m

function z = my_pskdemod(y , m) 
 
%this function demodulate the psk modulated signal, here y is the modulated 
%signal with m-psk, and z is the output. here y can be row or coulmn 
%vector, m is the integer power of 2 and , z should be a row vector. 
 
%santosh shah, The LNM IIT Jaipur (India)(santosh.jnt@gmail.com) 24/04/07 
 
%i have to check if M is equal to the power of 2 and x is in between 0 to 
%M-1 so.. 
if log2(m)~= floor(log2(m)) 
    error('Please check the value of m that you have provided for type M-QAM.'); 
end 
 
%now comparing the data from c's vector after rounding the input data. 
% Allocate space for output 
z = zeros(size(y)); 
 
%now generating the cancellation points 
t = (0:m-1); 
c  = exp(2*pi*t*(m-1)/m*(-i)); % taking the concept of cosx + i*sinx 
 
% Slicer: Find closest constellation symbol, symbol-by-symbol. 
for k = 1:length(y) 
    [nil ind] = min(abs(y(k) - c)); 
    z(k) = ind - 1; 
end