Patent ID: 6772384
Filing Date: 2004-08-03
Classification: G11B,H03M,H04L

Abstract:
An erasure correction method for correcting an error by using plural different types of error correcting codes said method comprising:demodulating modulated data into demodulated data having the plural different types of error correcting codes added thereto; setting an erasure flag for a demodulation error at the demodulation time; reading the demodulated data for each of the plural different types of error correcting codes, and erasure-correcting errors in the demodulated data including the demodulation error indicated by the erasure flag; erasing the erasure flag for the demodulated data which is erasure-corrected for each of the correcting codes and using an erasure flag which is not erased at the correction by a precedent correction code for performing erasure-correction by a subsequent correcting code, wherein the demodulated data having the plural different types of the error correcting codes added thereto includes a product code comprising an outer code and an inner code; reading the demodulated data for each codeword of the inner code to erasure-correct an error in the demodulated data, as well as erasing the erasure flag for the corrected demodulated data; reading the demodulated data for each codeword of the outer code to erasure-correct an error by using an erasure flag which is not erased by the inner code, as well as erasing the erasure flag for the corrected demodulated data; and reading again the demodulated data for each codeword of the inner code to erasure-correct an error using an erasure flag which is not erased by the outer code, as well as erasing the erasure flag for the corrected demodulated data.