A method for encoding a binary input sequence x(0,1) to obtain a duobinary output sequence y(+1,0,-1) is provided. The duobinary coding technique always provides an output bit y.sub.k =0 when the corresponding bit x.sub.k =0; bits y.sub.k alternatively assume a logical level "+1" and "-1" whenever an...http://www.google.com/patents/US5892858?utm_source=gb-gplus-sharePatent US5892858 - Duobinary coding and modulation technique for optical communication systems
