On the construction of constrained codes employing sequence replacement techniques


Adriaan van Wijngaarden and Kees A. Schouhamer Immink

ABSTRACT

We report on a new method for translating user information into a constrained sequence in which prescribed subsequences are forbidden. The new method, termed sequence replacement technique, recursively removes all forbidden subsequences and the positions where the forbidden subsequences are removed are indicated at predefined positions at the beginning of the constrained sequence. The sequence replacement technique makes it possible to translate source words into codewords and vice versa by invoking an algorithmic procedure rather than performing the translation with a look-up table. The new method will be exemplified by constructing prefix-synchronized codes and maximum run-length-limited codes. It will be shown that the sequence replacement technique is efficient as the rate of the code is close to its theoretical maximum.

Key Words: constrained code, recording code, run-length-limited



Last updated: 12-April-97