US 7,010,065 B2 · Method and apparatus for word synchronization with large coding distance and fault tolerance for PRML systems

Abstract

A method and apparatus are provided for word synchronization with large coding distance and fault tolerance for a partial-response maximum-likelihood (PRML) data channel in a direct access storage device (DASD). A Viterbi detector receives equalized PR4 samples including a predefined word synchronization pattern. The Viterbi detector is a dedicated detector optimized for detecting the predefined word synchronization pattern. The Viterbi detector includes a two-state Viterbi trellis and a word synchronization detector for the two-state Viterbi trellis. The predefined word synchronization pattern includes only even length magnets. The predefined word synchronization pattern is a repetition code including pairs of ones and pairs of zeros and includes multiple pattern match sequences. The Viterbi detector is optimized with branches removed from the Viterbi trellis, thus increasing coding distance. The two-state Viterbi trellis and word synchronization detector of the Viterbi detector operate on a 2T basis, where 1/T is the sample rate.

Claims15

Dependent claims

Apparatus for word synchronization with large coding distance and fault tolerance for a partial-response maximum-likelihood (PRML) data channel in a direct access storage device (DASD) comprising:

a Viterbi detector for receiving equalized PR4 samples including a predefined word synchronization pattern;
said Viterbi detector being optimized for said predefined word synchronization pattern;
said Viterbi detector including
a two-state Viterbi trellis;
a word synchronization detector for said two-state Viterbi trellis;
said word synchronization detector implements a difference metric for said two-state Viterbi trellis and includes a three-way multiplexer;
said three-way multiplexer includes an input of added incoming samples, said added incoming samples represented by (YK-2+YK-3) and
said two-state Viterbi trellis and said word synchronization detector are operated on a 2T basis, where 1/T is the sample rate.

5 more elements

A method for word synchronization with large coding distance and fault tolerance for a partial-response maximum-likelihood (PRML) data channel in a direct access storage device (DASD) comprising the steps of:

sensing a readback signal including a predefined word synchronization pattern said predefined word synchronization pattern including only one or more sequential pairs of zeros and one or more sequential pairs of ones;
said predefined word synchronization pattern including multiple pattern match sequences;
providing a dedicated Viterbi detector optimized for said predefined word synchronization pattern and said Viterbi detector including a two-state Viterbi trellis and a word synchronization detector for said two-state Viterbi trellis;
applying equalized PR4 samples from said readback signal including said predefined word synchronization pattern to said dedicated Viterbi detector;
detecting a predefined number of said multiple pattern match sequences of said predefined word synchronization pattern with said Viterbi detector;
and
generating a start of data trigger for the partial-response maximum-likelihood (PRML) data channel.

4 more elements

Dependencies are inferred from the claim text.

Method and apparatus for word synchronization with large coding distance and fault tolerance for PRML systems

Life of this patent

Method and apparatus for word synchronization with large coding distance and fault tolerance for PRML systems

Life of this patent

Abstract

Claims15