Codes with synchronization capability

A synchronizable (SC_{s}) code has the property that the punctuation (comma or no comma, comma indicating that the next symbol is the beginning of a new code word) at a given position in a code symbol stream can always be determined by observing at most s code symbols in the neighborhood of the position in question. The construction of SC_{s} dictionaries and the mechanization of synchronizers using nonlinear shift registers are explained in detail. Necessary and sufficient conditions for the existence of SC_{s} codes with specified word lengths are derived. By allowing unequal word lengths in the code, it is demonstrated that a substantial saving in average word length and information rate can be accomplished over other recently proposed codes having synchronization capability.