Error correction method and apparatus
US4849975A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 10, 1987 |
| Grant date | Jul 18, 1989 |
| Priority date | — |
| Expiry date | Nov 10, 2007 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03M13/15
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A method and apparatus is disclosed for correcting up to two byte errors in encoded uncorrected data in records of a predetermined length. As illustrated, the records are subblocks of a block in a multi-level error correction code format. The data is read from a storage device and corrected by decoding and processing four syndromes of error (S.sub.1, S.sub.2, S.sub.3, S.sub.0) that are generated by means disclosed in the prior art. These syndromes are decoded in response to uncorrected errors in any one record by computing vectors (P, Q, and R), which are functions of the four syndromes. Binary numbers (u and v) are then determined from these vectors by table look-up to enable calculation of one value (d) from the sum of said binary numbers for determining error locations. Another value (t), mathematically related to said one value, is then determined by table look-up and the error location values (y and z) are determined by calculating the offset of binary numbers (u,v) from the other value (t). Finally, error patterns (E.sub.y and E.sub.z) are determined by table look-up.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.