Information data transmission method

The coding system converts a data bit sequence into a binary channel bit sequence. The data bits are divided into successive blocks, each with the same number of bits, subsequently converted into channel blocks with a greater number of bits, made up of a block of information bits and a block of separation bits. After converting the data bit blocks into information bit blocks each of the possible channel bit sequences incorporating the information bit blocks is obtained. The sum of the number of separation bits and the number of information bits is obtained for each possible sequence and an indication signal denotes the sequences with a sum value lying within two required limits. The sequence which causes the min. imbalance of the DC current is selected from those for which the indication signal is provided. The coding system is used for data transmission or for optical or magnetic recording. Data words in m-bit source code are encoded to decodable information words in n-bit channel code, wherein n is greater than m. Individual blocks on n-channel bits being representative for individual data words in a second channel code are converted to a sequence of bit blocks following each other and alternated with each other amounting to ni1 = n bits and separating bit blocks with ni2 bit number. A flow of alternated information blocks and separating blocks is then converted to a bistable modulated channel encoded signal. The modulated channel encoded signal is derived from a channel encoded modulation signal being formed in advance and consisting of a flow of alternated information blocks and separating blocks. Formation of the modulation signal comprises a generating process during which a set of possible sequences is generated for each block set to be processes and whose representation is to be applied to a transmission line after subsequent NRZ-1 modulation, whereby each sequence of the set of possible sequences contains said at least one block of ni1 information bits supplemented with one of possible bit combinations in said at least one separating block of ni2 bits. The number ai1 of logic zeroes between logic ones is then compared in each of the possible sequences with the highest admissible number of k bits and the lowest admissible number of d bits and selection of sequences in which the number ai1 agrees with the condition d is less than or equal to ai1 that is in turn less than or equal to k, wherein d is greater than or equal to 2 and k is less than or eq