%-------------------------------------------------------------
%  Compute cross-correlation of two oversampled Walsh-Hadamard
%  functions.
%-------------------------------------------------------------

%--- compute hadamard sequences of length 2^7 ---
H = hadamard(128);
h1 = H(63,:);
h2 = H(64,:);

%--- oversample by 4 ---
osh1 = ones(4,1)*h1;
osh1 = osh1(:);
osh2 = ones(4,1)*h2;
osh2 = osh2(:);


%--- compute cross-correlation ---
h12 = xcorr(osh1,osh2);
plot([-511:511],abs(h12)/512); grid on
axis([-500 500 0 1])
ylabel('Normalized Cross-correlation')
xlabel('Delay(samples)')