Wyner-Ash convolutional encoding of digital data stream - by characterising position of erroneous bit within subdivision of input word combined with original data word

摘要

A subword Wyner-Ash encoding unit (30) is used with a position detection unit (40). The former unit comprises five Exclusive-OR gates (31a-31e), four double delay stages (32a-32d), a further give Exclusive-OR gates (33a-33e), a single delay stage (34) and an output Exclusive-OR gate (35). A number of data words are combined with input words of length m divided into k subwords of length n. Each input word syndrome pattern contains a position detection characterising the position of an erroneous subword, and a subword syndrome pattern characterising the position of an erroneous bit therein. USE/ADVANTAGE - Esp. for video codec. Encoding is simplified without need for a parity bit to be produced for each individual data word of the serial data stream, and transmission channel capacity is better utilised.