Decoding method and apparatus with maximum likelihood sequence estimation

Abstract

A magnetic recording apparatus includes a magnetic recording medium for recording a binary signal; a magnetic head for detecting the binary signal; an amplifier for amplifying the binary signal detected by the magnetic head; a channel for outputting the amplified binary signal in the form of a timing value sequence, the timing value sequence alternatively providing positive and negative peak values following the rule of the binary signal that recorded in the recording medium; a temporary judging unit for judging a presently input timing value of the timing value sequence supplied from the channel as one of the positive peak value, in accordance with the relationship with a preceding timing value temporarily judged as one of the positive and negative peak values; a final judging unit for finally setting the preceding timing value as one of the positive and negative peak values and the intermediate value, in accordance with the relationship with the presently input and temporarily judged timing value; a counter for counting the number of input bits of the timing value sequence; a unit for resetting the counter when the timing value temporarily judged as one of the positive and negative peak values is output; a register for storing a decoded binary bit value; and a unit for overwriting the bit value in the register at the bit position corresponding to the count of the counter.