Abstract: A process for the base band modulation of a data signal on a magnetic support is characterized in that: (a) a bit value of 0 is marked if it follows an unmarked bit of value of 0 or a sequence of three consecutive unmarked bits of value 1; (b) a bit value 1 as marked if it follows a bit value 0 or a sequence of three consecutive unmarked bits of value 1, except if these rules (a) and (b) lead to marking the first bit of a sequence formed from three bits of value 1 followed by a bit of value 0. The minimum interfront in the modulated signal is equal to 1.5 T and the maximum interfront is equal to 4 T.

Abstract: The invention relates to a process for the transmission in blocks of digital information words with a correction capability. This process consists of transmitting in blocks digital information words, each information word having a length of n.sub.1 bits, in which with each sequence of n.sub.2 -k (n.sub.2 >k) of consecutive information words are associated k redundancy words of n.sub.1 bits each in which, for each order i (1<i<n.sub.2), the k bits of order i of the redundancy words are redundancy bits in accordance with a Hamming code (n.sub.2 0k, k). For each set of n.sub.2 linked words, each word is transmitted while being protected by an error detecting code. Several sets of linked words can be interlaced. The words of the same order or rank of each set form a group and the groups can be formed by frames.