US Patent 8005302 Data modulation/encryption method used in holographic storage system

The disclosure is a data modulation/encryption method used in a holographic storage system. The data modulation method includes steps of: receiving an original data sequence; arraying the original data sequence to a first matrix with n×n dimensions; multiplying the first matrix by a sparse matrix to generate a second matrix with n×n dimensions; executing a modulating and mapping procedure for generating a third matrix with (n+1)×n or n×(n+1) dimensions, wherein the third matrix is composed of a modulation part and an extra part; and, storing the third matrix; wherein the sparse matrix is a binary matrix, a total number of elements in each row of the sparse matrix is odd, all rows of the sparse matrix have a same even number of bit 1, all columns of the sparse matrix have a same even number of bit 1, and the sparse matrix has an inverse matrix.