The method of poles: a coding method for constrained channels

A method for solving coding problems involving channels restricted by finite state constraints is presented. The method was introduced by P.A. Franaszek (1969) and is based on the computation of a set of principal states. It is proved that state-independent decoding is guaranteed. The main result is that the transducer constructed using the method is a local automaton in its output. The method is also related to recent work in symbolic dynamics by R.L. Adler (1987), B. Marcus (1985), and others. Typical applications are coding methods for magnetic storage.<
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