CONSTANT LENGTH TO NON-CONSTANT LENGTH CODE CONVERSION USING MARKOV PROCESS

摘要

In an apparatus for generating variable length codewords c(ai) and c(aj) responsive to corresponding fixed length codewords b(ai) and b(aj), where ai and aj are source alphabet characters, ai epsilon A1 and aj epsilon A2, ambiguity arises whenever any fixed length character to be encoded can instantaneously represent source characters ai and aj drawn from two or more dissimilar alphabets i.e. A1 or A2. This is resolved by the inclusion of a Markov processor in combination with the apparatus. The processor establishes the point in the sequence when transitions occur between fixed length characters in one alphabet to fixed length characters in another alphabet by the message context. The processor includes a map of state and transition paths. This map models certain statistical regularities of runs of fixed code elements and the relative likelihood that an ambiguous fixed code character appearing in a first run belongs to a given alphabet. The processor, starting from an arbitrary initial position, tracks any given run of fixed code characters applied to the encoder in terms of a succession of states and paths.