Patent EP0194888A2 successfully refreshed from Google Patents.
EP0194888A2
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EP
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Error detection
Assignee: Sony Corp
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Filing: 1986-03-13
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Granted: —
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Expires: 2006-03-13
Abstract
Abstract A method is provided for detecting and correcting error words in a data block formed of a plurality of words each consisting of or comprising a predetermined number of bits of digital signal, the block including first error check words, . second error check words not completely coincident with the first words, and a third error check work. The method comprises first executing an error check by the third check word and concluding that an error is present in each of the words of the data block when an error is detected, executing second and third error checks by the respective first and second error check words, and thereupon setting one of three states, namely a state in which each of the words is correct, a state in which each of the words has an error, and a state in which it is yet undetermined whether each word is correct or has an error; and when words having errors or undetermined words are included in the first and second words series, changing the state of the words having errors or the undetermined words.
Inventors
- 👤 Takuji C/O Sony Corporation Himeno
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 08:22
CPC Classifications
G; G11; G11B; G11B20/00; G11B20/10; G11B20/18; G11B20/1806; G11B20/1809
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
285 words
A method of detecting error words in a data block formed of a plurality of words each comprising a predetermined number of bits of a digital signal, and including first error check words for a first word series (P) established by selecting a predetermined number of words from among said plurality of words, second error check words for a second word series (Q) established by selecting a predetermined number of words from among said plurality of words in a manner such that said last-mentioned predetermined number of words does not completely coincide with the words of said first word series (P), and a third error check word (CRC) for said plurality of words, the method comprising the steps of: executing an error check for said data block by said third error check word (CRC) and determining that an error is included in each of said words forming said data block when an error is detected, executing an error check with respect to said respective first and second word series (P,Q) by said first and second error check words after completion of the execution of said error check by said third error check word (CRC), and after completion of the execution of said error check, with respect to all of the words in each of said data blocks, setting any one of three states comprising a state (S) in which each of said words is correct, a state (E) in which each of said words has an error, and a state (N) in which it is not determined yet whether each of said words is correct or has an error in accordance with a situation of generation of an error in each of said data blocks.
Claim 2
Independent Claim
285 words
A method of detecting error words in a data block formed of a plurality of words each comprising a predetermined number of bits of a digital signal, and including first error check words for a first word series (P) established by selecting a predetermined number of words from among said plurality of words, second error check words for a second word series (Q) established by selecting a predetermined number of words from among said plurality of words in a manner such that said last-mentioned predetermined number of words does not completely coincide with the words of said first word series (P), and a third error check word (CRC) for said plurality of words, the method comprising the steps of: executing an error check for said data block by said third error check word (CRC) and determining that an error is included in each of said words forming said data block when an error is detected, executing an error check with respect to said respective first and second word series (P,Q) by said first and second error check words after completion of the execution of said error check by said third error check word (CRC), and after completion of the execution of said error check, with respect to all of the words in each of said data blocks, setting any one of three states comprising a state (S) in which each of said words is correct, a state (E) in which each of said words has an error, and a state (N) in which it is not determined yet whether each of said words is correct or has an error in accordance with a situation of generation of an error in each of said data blocks.
Claim 3
Dependent Claim
147 words
A method according to claim 1, wherein said step of setting any one of said three states (S,E,N) comprises the steps of: when a word which was determined to have an error does not exist in said data block, deciding that all the words in said data block are correct; when one or more words which were determined to have errors exist in said data block and also words which were determined to be correct do not exist in said data block, deciding that all the words in said data block have errors; and when one or more words which were determined to have errors exist in said data block and also one or more words which were determined to be correct exist in said data block, deciding that it is not determined yet whether all the words in said data block are correct or have errors.
Claim 4
Dependent Claim
84 words
A method according to claim 1, including a step of correcting the error words, said step comprising, when words having errors or undetermined words are included in each of said first and second word series, changing the state of said words having the errors or said undetermined words to another state in accordance with a situation of occurrence of said any one of said three states (S,E,N) of each of said words in said first and second word series (P,Q), thereby correcting the errors.
Claim 5
Dependent Claim
148 words
A method according to claim 3, wherein said step of setting any one of said three states (S,E,N) comprises the steps of: when a word which was determined to have an error does not exist in said data block, deciding that all the words in said data block have no error; when one or more words which were determined to have errors exist in said data block and also words which were determined to be correct do not exist in said data block, deciding that all the words in said data block have errors; and when one or more words which were determined to have erorrs exist in said data block and also one or more words which were determined to be correct exist in said data block, deciding that it is not determined yet whether all the words in said data block are correct or have errors.
Claim 6
Dependent Claim
71 words
A method according to claim 3, wherein said error correcting step comprises the steps of: when said words having errors or said undetermined words are corrected using only the correct words, deciding that each of said words was corrected to the correct word; and when said words having errors are corrected using the words including said undetermined words, deciding that said words having errors were corrected to words having undetermined states.
Claim 7
Dependent Claim
77 words
A method according to claim 3, wherein in the case where an error is detected at least once when the error check is performed with respect to each of said first and second words series, a step of instructing this fact is provided, and when an instruction indicating that an error was detected in said step is not issued, it is decided that each of said words is correct and said error correcting step is not executed.
Claim 8
Dependent Claim
141 words
A method according to claim 4, comprising the steps of: in the case where an error is detected at least once when the error check is performed with respect to each of said first and second word series, instructing this fact; when words which were determined to have parity check errors with respect to all the words in each of said data blocks exist in said data block and also a word which was determined to be correct does not exist in said data block, cancelling issuance of said instruction; and when words having the undetermined state are included in each of said data blocks at the end of said error correcting process, deciding that said words are words having errors if said instruction is issued and deciding that said words are the correct words if said instruction is not issued.
References Cited (Backward Citations)
No citation records indexed.
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