Patent attributes
A method of determining a coordinate value of a position with respect to patterns of a substrate using a sensing device is provided. Each pattern represents respective sequences. Each sequence consists of a repeating codeword of a cyclic position code. The cyclic position code has length n1 and minimum distance dmin1. The method includes sensing, using the sensing device, at least pan of h1 of the corresponding patterns, where h1≧2, obtaining, from each of h1 sensed patterns, a respective subsequence of length w1 symbols, where w1≧n1−dmin1+1, mapping each of the subsequences to a respective mapped codeword of the cyclic position code, determining an offset indicative of the position, in the corresponding, sequence, between each mapped codeword and the codeword, deriving, for each of h1−1 pairs of the first sequences, a difference between the corresponding pair of offsets, and thereby deriving a respective difference and as such the coordinate value.
