Patent ID: 8159376

Claim:
A method of encoding N-symbol data patterns into consecutive M-symbol codewords, where M is greater than N, the method comprising: for groups of three temporally adjacent ones of the M-symbol codewords, including for each of a series of adjacent time intervals, a current codeword in a current time interval, a preceding codeword immediately preceding the current codeword in a preceding time interval, and a bi-preceding codeword immediately preceding the preceding codeword in a bi-preceding time interval: dividing a set of signal nodes into a first group of signal nodes having symbols of a first symbol type in the preceding codeword and a second group of signal nodes having symbols of a second symbol type in the preceding codeword; identifying one or more first signal nodes in the first group of nodes having one or more first symbol transitions from the second symbol type to the first symbol type between the bi-preceding codeword and the preceding codeword, and one or more second signal nodes in the second group of signal nodes having one or more second symbol transitions from the first symbol type to the second symbol type between the bi-preceding codeword and the preceding codeword; setting the symbol type of symbols on the one or more first signal nodes in the current codeword to the first symbol type and the symbol type of symbols on the one or more second signal nodes in the current codeword to the second symbol type; and encoding a current N-symbol pattern into symbols in the current codeword, the current codeword expressed as one or more second symbol transitions on a remainder of the first group of signal nodes which excludes the one or more first signal nodes, and one or more first symbol transitions on a remainder of the second group of signal nodes which excludes the one or more second signal nodes.