An encoder uses an input file of data and a key to produce an output symbol. An output symbol with key I is generated by determining a weight, W(I), for the output symbol to be generated, selecting W(I) of the input symbols associated with the output symbol according to a function of I, and generating...http://www.google.ca/patents/US6307487?utm_source=gb-gplus-sharePatent US6307487 - Information additive code generator and decoder for communication systems
