function B = SymbolToBitStream(X,Nbits);
% B = SymbolToBitStream(X,Nbits);
%
% MSB first


Lx = length(X);
Lb = Lx*Nbits;
B = zeros(1,Lb);

for n = Nbits:-1:1,
   U = floor(X./2^(n-1));
   B(Nbits-n+1:Nbits:Lb)=U;
   X = X - 2^(n-1)*U;
end;