High efficiency, error minimizing coding strategy method and apparatus

• US RE43,883 E1
• Filed: 12/19/2011
• Issued: 12/25/2012
• Est. Priority Date: 01/22/2001
• Status: Expired due to Fees

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Inventors: Seabury, John, McCarthy, Steve
• Primary Examiner(s): ABRAHAM, ESAW T
• Application Number:
  US13/330,177
• Time in Patent Office: 372 Days
• Field of Search: 714/702, 714/742, 714/752, 714/758, 714/799
• US Class Current: 714/758
• CPC Class Codes: N/A

Abstract

A method for creating a high efficiency, error minimizing code is provided. In addition, an apparatus having a high efficiency, error minimizing code is provided. In particular, the present invention provides a high efficiency, error minimizing code for use in connection with systems having a communication channel in which identifiable dominant errors occur, and that is used to transmit data that may be usefully applied in the system even though the received signal is not exactly equal to the original signal. Furthermore, the present invention provides a code that may be used to constrain the effects of dominant errors in a communication channel.

Claims

1. A method of encoding data in digital communication systems for reducing effect of errors comprising the steps of:

providing a communications channel having a circuit at first and second ends of the communications channel and a code space with a plurality of code words;

determining dominant error events for said communications channel including effects of said dominant error events on said code words in said code space;

assigning user values to said code words in said code space;

determining a maximum tolerable deviation between user values submitted to transmission at a the first end of said communications channel and corresponding user values as received at a the second end of said communications channel;

forming groups of interdependent code words in said code space based on said dominant error events;

multiplying the maximum tolerable deviation by two to obtain a maximum number of code words, that may directly interdepend with any code word;

removing code words from said code space, so that no code words having more than M directly interdependent code words remain in said code space.

2. The method of claim 1 further including the step of:

reassigning user values to the non-removed code words, such that occurrence of a dominant error results in a received user value that is within the maximum tolerable deviation for all user values assigned to the non-removed code words.

3. The method of claim 2 including the steps of:

reassigning two or more user values to one code word.

4. The method of claim 1, wherein said code words are expressed as m-ary code.

5. The method of claim 1, wherein said communications channel comprises a channel of a computer disk drive.

6. A method of encoding data in digital communication systems for reducing effect of errors comprising the steps of:

providing a communications channel having a circuit at first and second ends of the communications channel and a code space with a plurality of code words;

determining a dominant error event for said communications channel including effects of said dominant error event on said code words in said code space;

assigning user values to said code words in said code space;

determining a maximum tolerable deviation between user values submitted to transmission at a the first end of said communications channel and corresponding user values as received at a the second end of said communications channel;

forming groups of interdependent code words in said code space based on said dominant error event;

multiplying the maximum tolerable deviation by two to obtain a maximum number of code words, M, that directly interdepend with any code word;

removing code words from said code space, so that no code words having more than M directly interdependent code words remain in said code space.

7. The method of claim 6 further comprising:

determining a second dominant error event for said communications channel.

8. The method of claim 6 further including the step of:

reassigning user values to the non-removed code words, such that occurrence of a dominant error results in a received user value that is within the maximum tolerable deviation for all user values assigned to the non-removed code words.

9. The method of claim 8 including the steps of:

reassigning two or more user values to one code word.

10. The method of claim 6, wherein said code words are expressed as m-my code.

11. The method of claim 6, wherein said communications channel comprises a channel of a computer disk drive.

12. The method of claim 6, wherein said communications channel can tolerate a difference between a user value as transmitted and a user value as received.

13. An apparatus for encoding data comprising:

a decoder circuit configured to

communicate data that is encoded using a code space having a plurality of code words that are correlated to user values;

determine dominant error events and an effect of the dominant error events on the code words in the code space;

identify groups of interdependent code words in said code space based on the effect of the dominant error events on the code words;

determine a limit for the number of code words in the identified groups;

modify the code space by removing code words from said code space based upon the determined limit and the identified groups; and

communicate data that is encoded using the modified code space.

14. The apparatus of claim 13, wherein the decoder circuit is configured to communicate with a storage circuit and wherein the determined dominant error events include dominate error events associated with memory accesses to the storage circuit.

15. The apparatus of claim 13, further including a non-volatile storage circuit that is linked to the decoder circuit over a communications channel and wherein the dominant error events are associated with differences between user values stored in the storage circuit and user values determined from code words received at the decoder circuit.

16. The apparatus of claim 13, wherein the decoder circuit is configured to assign user values to the code words of the modified code space as a function of differences in the user values and the identified groups.