Resolving block method for synchronization correction in run-length limited codes
AssigneeInternational Business Machines Corporation
InventorsRoy Lee Adler, Martin Aureliano Hassner, Bruce Kitchens
Life of this patent
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Abstract
An efficient method and apparatus corrects synchronization problems in the recovery data stored on magnetic media. Resolving blocks are inserted into the unconstrained data string at specified intervals. A resolving block is constructed to do two things: reset the encoding automaton and produce in the constrained data string blocks which allow correction of synchronization. Before decoding, synchronization is corrected. The constrained data string is decoded, and then the resolving block removed. The blocks are inserted before run-length limited encoding occurs and deleted after run-length limited decoding takes place. The run-length limited encoder and decoder are unchanged.
Claims12
A method to correct synchronization problems in channel codes generated by an encoder implemented as a finite state automaton comprising the steps of:
- inserting resolving blocks into an unconstrained data string at specified intervals, the resolving blocks being chosen to reset the automaton and produce in a constrained data string blocks which allow correction of synchronization;
- encoding the unconstrained data string with the inserted resolving blocks to generate a channel constrained data string containing the synchronizing blocks at specific locations;
- passing the constrained data string through a channel;
- using the synchronizing blocks to insure correct synchronization;
- decoding the synchronized and constrained data string to recover the original unconstrained data string with resolving blocks;
- and
- deleting the resolving blocks from the recovered unconstrained data string.
A communication channel with synchronization correction comprising:
- a resolving block inserter inserting resolving blocks into an unconstrained data string at specified intervals;
- a channel encoder implemented as a finite state automaton, the resolving blocks being chosen to reset the automaton and produce in a constrained data string blocks which allow correction of synchronization, said encoder encoding the unconstrained data string with the inserted resolving blocks to generate a channel constrained data string containing the synchronizing blocks at specific locations;
- a channel though which the constrained data string is passed;
- a synchronizer receiving the constrained data string from the channel and using the synchronizing blocks to insure correct synchronization;
- a decoder connected to the synchronizer and decoding the synchronized and constrained data string to recover the original unconstrained data string with resolving blocks;
- and
- a resolving block deleter deleting the resolving blocks from the recovered unconstrained data string.
Dependencies are inferred from the claim text.