Method for correcting multiple erroneous symbols in error correcting encoded data
 A method for correcting multiple erroneous symbols included in data produces a demodulation flag indicating whether demodulation based on a modulation code such as EFM or ETM is possible. The demodulation flag is used in decoding the data based on the error correcting code. Producing the error locations during decoding in accordance with a Reed-Solomon code comprises the steps of producing an index using ##EQU1## provided .sigma..sub.1, .sigma..sub.2 and .sigma..sub.3 represent coefficients of an error location polynomial, k.sub.1 represents .sigma..sub.1.sup.2 +.sigma..sub.2 and k.sub.2 represents .sigma..sub.1 .sigma..sub.2 +.sigma..sub.3, reading out virtual roots from a specified memory related to the index, and transforming the virtual roots (Z.sub.1, Z.sub.2 and Z.sub.3) into error locations (x.sup.j1, x.sup.j2 and x.sup.j3) in accordance with the following equations. EQU x.sup.j1 =Z.sub.1 (k.sub.1)+.sigma..sub.1 EQU x.sup.j2 =Z.sub.2 (k.sub.1)+.sigma..sub.1 EQU x.sup.j3 =Z.sub.3 (k.sub.1)+.sigma..sub.1 
Samsung Electronics Co., Ltd.
G G H
G11B G11B H03M
additional inventional inventional
Seok-jeong Tae-shik
Lee Joo