1. A method of transmitting a digital information signal formed of a plurality of sequences of information words, each word being of a predetermined bit length with each such sequence of words occurring in a respective input channel, and with check words included in the transmitted signal to enable correction of errors occurring in the signal as a result of transmission, comprising the steps of applying a first block of words, taken one from each such input channel, and having a first arrangement state, to a first error-correcting encoder to generate a series of k first check words; delaying each of the words in said first block and each of the k first check words by a respective different delay time to provide a resulting second block of words in a second arrangement state; applying said second block of words to a second error-correcting encoder to generate a series of k second check words; and transmitting said second block of words together with said second check words; wherein said first and second check words are generated to satisfy a parity check matrix having n columns and k rows, and in which each element of one predetermined row is selected from digital values from zero to 2.sup.m -1, so that the same value does not appear twice in said predetermined row, and wherein the elements in the remaining rows are selected to be a given power, for all the elements in each respective row, of the corresponding elements in said predetermined row, where m is the bit length of said data words and n is the number of words in each block formed of the digital words of the information signal together with the associated check words.
1. A method of transmitting a digital information signal formed of a plurality of sequences of information words, each word being of a predetermined bit length with each such sequence of words occurring in a respective input channel, and with check words included in the transmitted signal to enable correction of errors occurring in the signal as a result of transmission, comprising the steps of applying a first block of words, taken one from each such input channel, and having a first arrangement state, to a first error-correcting encoder to generate a series of k first check words; delaying each of the words in said first block and each of the k first check words by a respective different delay time to provide a resulting second block of words in a second arrangement state; applying said second block of words to a second error-correcting encoder to generate a series of k second check words; and transmitting said second block of words together with said second check words; wherein said first and second check words are generated to satisfy a parity check matrix having n columns and k rows, and in which each element of one predetermined row is selected from digital values from zero to 2.sup.m -1, so that the same value does not appear twice in said predetermined row, and wherein the elements in the remaining rows are selected to be a given power, for all the elements in each respective row, of the corresponding elements in said predetermined row, where m is the bit length of said data words and n is the number of words in each block formed of the digital words of the information signal together with the associated check words. 3. A method of transmitting a digital information signal according to claim 1, wherein said step of applying the first block of words includes delaying the words of at least certain ones of the input channels by an amount different from any delay imparted to the words of the remaining input channels prior to the application thereof to said first error correcting encoder.