Patent ID: 9559725
Date: 2017-01-31
CPC Classifications: H03M

Claim:
1. A coding device comprising encoder circuitry configured to encode data into low density parity check (LDPC) inner codewords and multiple-strength Reed-Solomon (RS) outer codewords, wherein each Reed-Solomon outer codeword has a code length N equal to the sum of a data length K and a number of parity length R, and has a symbol size S and a code rate K/N, wherein the strength of the outer codewords is varied by changing at least one of the code length N, data length K, parity length R, symbol size S and code rate K/N to form a plurality of multiple-strength RS outer codewords, wherein each of the multiple RS outer codewords form a column that include data sector rows and parity sector rows, a total number of parity and data sectors remaining the same even with outer codewords of different strengths, and wherein LDPC codes as first level inner codewords are corrected with multiple-strength RS outer codewords as second level outer codewords starting with the lowest code rate (K/N) to iteratively correct data in a two level data protection mode.