Error correction in digital data storage device

Abstract

A data error-correction method, applied in an optical storage device, for correction an original data read from an optical storage media. A bit modulation is performed on the original data. The data is thus checked to see if the original data is error. If error exists, an error bit is added to the error-contained modulated data. An error-correction procedure is carried out to correct error in the error-contained modulated data.

What is claimed is:  
     
         1 . A data error-correction method, applied in an optical storage device, for correction an original data read from an optical storage media, comprising the steps of: 
 performing a bit modulation on the original data;    checking the data to see if the original data is error;    if error, adding an error bit to the error-contained modulated data; and    carrying out an error-correction procedure to correct error in the error-contained modulated data.    
     
     
         2 . The method of    claim 1   , wherein the step of carrying out the error-correction procedure further comprises the steps of: 
 computing syndrome values;    determining the number of error flags if at least one of the syndrome values is not zero;    computing a divisor of an error value if the number of the error flags is greater than 4, otherwise tagging an erasure bit to the decoded data group;    computing a dividend of the error value if the divisor is not zero, otherwise tagging an erasure bit to the decoded data group;    computing the error value;    correcting error if the times of computing the error value is less than four.    
     
     
         3 . The method of    claim 1   , wherein the step of performing the bit modulation comprises carrying out an eight-to-fourteen bit encoding operation.  
     
     
         4 . The method of    claim 1   , wherein the step of checking the modulated data further comprises a step of comparing the data by a built-in look-up table in the optical storage device.  
     
     
         5 . The method of    claim 1   , wherein the optical storage device is a CD-compatible drive.  
     
     
         6 . The method of    claim 1   , wherein the optical storage media is a CD-compatible disk.  
     
     
         7 . A data error-correction method, applied in an optical storage device, for correcting an original data read from an optical storage media, comprising the steps of: 
 performing a bit modulation on the original data;    checking the data to see if the original data is error;    if error, adding an error bit to the error-contained modulated data;    delaying the modulated data into a data group;    computing a plurality of syndrome values corresponding to the data group;    checking to see if the syndrome values are all zero;    when not all the syndrome value are zero, checking to see if any error bit is present in the modulated data of the data group;    when total amount of the error bit in the data group does not exceed a threshold value, correcting a divisor or a dividend of the error modulated data to the error modulated data; and    when total amount of the error bit exceeds the threshold value, tagging an erasure bit to the error-contained modulated data.    
     
     
         8 . The method of    claim 7   , wherein the step of correcting the divisor or the dividend comprises the steps of: 
 carrying out a computation to find a division number from the error value;    checking to see if the division number is zero, wherein 
 when the division number is zero, tagging the error value with an erasure bit;  
 when the division number is non-zero, carrying out a computation to find a divide number of the error value as well as an error value and an error value computation count; and  
   correcting all errors in the data group.    
     
     
         9 . The method of    claim 7   , wherein the step of performing the bit modulation comprises carrying out an eight-to-fourteen bit encoding operation.  
     
     
         10 . The method of    claim 7   , wherein the step of checking the modulated data comprises a step of comparing the digital data by an in-built look-up table in the optical storage device.  
     
     
         11 . The method of    claim 7   , wherein the optical storage device is a CD-compatible drive.  
     
     
         12 . The method of    claim 7   , wherein the optical storage media is a CD-compatible disk.  
     
     
         13 . A data error-correction method, applied in an optical storage device, for correction an original data read from an optical storage media, comprising the steps of: 
 performing a bit modulation operation on the original data to obtain a modulated data;    adding an error flag if the modulated data is illegal;    delaying the modulated data with the error flag if any into a data group;    performing a decoding operation on the data group, wherein the decoding operation further comprising the steps of:    computing syndrome values;    determining the number of error flags if at least one of the syndrome values is not to zero;    computing a divisor of an error value if the number of the error flags is greater than a threshold value, otherwise tagging an erasure bit to the decoded data group;    computing a dividend of the error value if the divisor is not zero, otherwise tagging an erasure bit to the decoded data group;    computing the error value;    correcting error if the times of computing the error value is less than the threshold value.    
     
     
         14 . The method of    claim 13   , wherein the bit modulation operation comprises a eight-to fourteen modulation (EFM) process.  
     
     
         15 . The method of    claim 13   , wherein the threshold value is 4.  
     
     
         16 . The method of    claim 13   , wherein the optical storage device is a CD-compatible drive.  
     
     
         17 . The method of    claim 13   , wherein the optical storage media is a CD-compatible disk.