Patent ID: 6480983
Filing Date: 2002-11-12
Classification: G11B,H03M

Abstract:
A method for detecting a next state of a NRZI modulated spectral-null trellis codeword generator, wherein each state corresponds to a starting value of a bounded digital sum variation (DSV) to be calculated for a sequence of NRZI modulated spectral-null trellis codewords, comprising the steps of:modifying a codeword generation state machine by adding a state transition to form a codeword digital sum variation (DSV) detection state machine, wherein the added state transition is an illegal state transition for the bounded digital sum variation (DSV); monitoring an output codeword from the codeword generator and a present state of the codeword generator using digital logic configured to implement a state transition of the codeword detection state machine; and outputting a digital code corresponding to the next state of the codeword generator.