function X = QAM_Mod(x,Nbits);% X = QAM_Mod(x,Nbits);%Lx = length(x);i = x(1:2:Lx);q = x(2:2:Lx);for n = 1:Lx/2,   i(n) = GrayCoding(i(n),Nbits);   q(n) = GrayCoding(q(n),Nbits);end;Levels = 2^Nbits;i = i - (Levels-1)/2;q = q - (Levels-1)/2;X = i + sqrt(-1)*q;% scaling for uniform bit distributionScale = 1./[0.7071;    1.5811;   3.2404;   6.5192];X = X*Scale(Nbits);