That's binary correlation. Can be done many ways actually
counting/changing or not sign/msb bit. Really depends what
you want to get from it.


"Peter L. Peres" wrote:
>
> Correlation: A simple way is to XOR incoming data with data-to-be-tested
> and count the 1's in the result. The fewer 1's the better the correlation.
> XOR is modulo-2 multiply without carry out (or in) and one (the?)
> correlation function is Fc=SumOf|Ai*Bi|. XOR produces this result when Ai
> and Bi are binary bits, but the sum is zero for high correlation because
> the carry in the XOR multiply is lost. In this case Fc=0 means 'all bits
> caused carry' (which was lost). Otherwise one would use an analog
> multiplier to check for correlation with analog signals, and aim for high
> Fc (not zero). Notice that in a binary XOR correlator an all 1's result
> means input and reference are 180 degrees out of phase, or complementary.

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