Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
279 words
An error correction method in decoding code words having first code blocks, including a plurality of information words arranged in a first arrangement and a plurality of first check words generated by a code having a Hamming distance of d 1 to said information words, and second code blocks including a plurality of information words arranged in a second arrangement and a plurality of first check words each having a plurality of information words and a plurality of first check words belonging to different one of said first blocks, and a plurality of second check words generated by a code having a Hamming distance of d 2 to said plurality of information words and said plurality of first check words, comprising the steps of: (al in a first decoding stage, at least detecting errors for said second code blocks and adding at least one type of flags representing a decoding status; and (b) in a second decoding stage, detecting errors for said first code blocks and correcting S 2 word errors and E word erasures satisfying 2S 2 + E ≦ d l - 1, where S 2 is the number of word errors at unknown locations and E is the number of erasures and determining error locations and error patterns, for a plurality of combinations of S 2 and E, determining the combination of S 2 and E having a high correction capability and a low probability of miscorrection based on the plurality of determined error locations and error patterns, and correcting the word error in the second decoding stage based on the error location and the error pattern of the selected combination of S 2 and E.
Claim 2
Dependent Claim
279 words
An error correction method in decoding code words having first code blocks, including a plurality of information words arranged in a first arrangement and a plurality of first check words generated by a code having a Hamming distance of d 1 to said information words, and second code blocks including a plurality of information words arranged in a second arrangement and a plurality of first check words each having a plurality of information words and a plurality of first check words belonging to different one of said first blocks, and a plurality of second check words generated by a code having a Hamming distance of d 2 to said plurality of information words and said plurality of first check words, comprising the steps of: (al in a first decoding stage, at least detecting errors for said second code blocks and adding at least one type of flags representing a decoding status; and (b) in a second decoding stage, detecting errors for said first code blocks and correcting S 2 word errors and E word erasures satisfying 2S 2 + E ≦ d l - 1, where S 2 is the number of word errors at unknown locations and E is the number of erasures and determining error locations and error patterns, for a plurality of combinations of S 2 and E, determining the combination of S 2 and E having a high correction capability and a low probability of miscorrection based on the plurality of determined error locations and error patterns, and correcting the word error in the second decoding stage based on the error location and the error pattern of the selected combination of S 2 and E.
Claim 3
Dependent Claim
36 words
An error correction method according to Claim 1 wherein said step of at least detecting errors includes error detection and error correction for S 1 words, where 2 S 1 f d 2 - 1 .
Claim 4
Dependent Claim
44 words
An error correction method according to Claim 1 wherein, in said second decoding stage, error locations and error patterns are parallelly or sequentially determined for the plurality of combinations of S 2 and E satisfying 2S 2 + E ≦ d l - 1.
Claim 5
Dependent Claim
16 words
An error correction method according to Claim 1 wherein said code words are doubly-encoded Reed-Solomon codes.
Claim 6
Dependent Claim
18 words
An error correction method according to Claim 1 wherein said code words are doubly-encoded cyclic redundancy check codes.
Claim 7
Dependent Claim
68 words
An error correction method according to Claim 1 wherein the decode result of the combination of S 2 and E having a minimum probability of miscorrection determined by the decoding result and the number of flags in a unit block is selected out of the plurality of decode results for the error locations and error patterns, and the word error is corrected based on the selected decode result.
Claim 8
Dependent Claim
190 words
An error correction system for correcting errors in an error correction method in accordance with Claim l, comprising: a syndrome generator (20) for generating a syndrome from an input signal; an arithmetic logic unit (241 for carrying out addition, division and multiplication on a Galois field; a translation circuit C21, 22) for translating α i to i and/or i to α i in any dimension α i of the Galois field; a counter (26) for counting a plurality of types of flags added to the input words; a memory circuit (25, 271 for storing the syndrome generated by said syndrome generator, the result of said arithmetic logic unit, the translation result of said translation circuit, the number of flags of the flagged input words counted by said counter and the flags added to said input signal; a program memory circuit (31) for storing a program for controlling said arithmetic logic circuit, said translation circuit and said memory circuit for effecting an error correction operation; and a control circuit (30, 32) for controlling an address of said program memory circuit in accordance with said program and the status of the flags.