Reed–Solomon Error Correction
Hard Drive Recovery - Reed–Solomon Error Correction
Reed–Solomon error correction is a method of error correction by evaluating a polynomial constructed from the data. The polynomial is evaluated at several points, and these values are either sent or recorded. If the receiver gets many of the points correctly, it can recover the original polynomial even if there are a few bad points.
The code was invented by Irving S. Reed and Gustave Solomon in 1960.
Features
- Reed-Solomon codes (R-S codes) are block codes. A fixed block of input data is processed into a fixed block of output data.
- Most of the R-S code schemes are systematic, i.e., some of the output codeword contains the input data in its original form.
- Standard R-S codes are capable of correcting up to 16 R-S symbol errors in each codeword.
- R-S codes are transparent; even if the channel symbols have been inverted somewhere along the line, the decoders will still operate. However, R-S codes will lose their transparency when the code is shortened. In this case, the missing bits in the shortened code will be filled by either zeros or ones, depending on whether the data is complemented or not.
Applications
R-S codes are used in a variety of commercial applications including CDs, DVDs and Blu-ray Discs to correct the burst errors associated with media defects. It is also used in communications technologies such as DSL, WiMAX, DVB and ATSC. In computer field, they are used in RAID 6 systems.
