## Reed–Solomon (RS) codes

RS codes are a subset of BCH codes that operate at the block level rather than the bit level. In other words, the incoming data stream is first packaged into small blocks, and these blocks are then treated as a new set of k symbols to be packaged in to a super-coded block of n symbols. The result is that the decoder is able to detect and correct complete errored blocks. It is thus possible for a whole block to be corrupted owing to a burst of errors in a deep fade, for example, and the receiver still to be able to reinstate the correct information. RS codes are often used in mobile radio systems where burst errors are common, either as an alternative to, or in addition to, interleaving. RS codes are also used as part of the error correcting mechanism in CD players. The inevitable scratches on the disk surface result in bursts of errors coming from the disc, making the RS code ideally suited to this task.

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