Patent ID: 6232895
Filing Date: 2001-05-15
Classification: H04L

Abstract:
An encoder for coding a serial bit stream of input data arranged in groups of N bit data words into serial output data arranged in codewords of 2N bits, comprising:a serial-parallel converter receiving said serial bit stream of N-bit data words and developing N-bit words in parallel;a logic circuit receiving said N-bit words in parallel and logically altering selected bits of said N-bit words; anda parallel-serial converter receiving the output of said logic circuit and producing said codewords of 2N bits;said encoder being configured so that N of the 2N bits in each said codeword are comprised of the N bits of the input data words, unchanged or inverted, andsaid encoder further being configured so that remaining bits in each of the codewords are determined so that, seen statistically, the codewords include approximately as many zeros as ones, so that each codeword is unique for each word, and that at least one of the codewords remains unique among said codewords despite bit stream shifting processes.