US Patent 7149955 Encoding and decoding apparatus and method with hamming weight enhancement

A Hamming weight encoder includes an input that receives user data including P symbols and a Hamming weight module that determines a Hamming weight of N of said P symbols. N and P are integers greater than one and N is less than or equal to P. The Hamming weight encoder also includes a comparing module that compares the Hamming weight to a Hamming weight threshold and an inverting module that selectively bitwise inverts bits in said N symbols based on said comparison.