About methods of constructing LDPC-codes with preset characteristics

The work presents algoritms for building test matrices for LDPC, which are codes based on a Tanner graph with a girth of 8. Other parameters of the graph, apart from the girth, include the division of degrees of character vertices: the ratio of portion of vertices with degrees 3 and 4 to their total number, as well as the speed of the code generated. The code is built for random speed and random division in linear time depending on the number of elements of the matrix.