To interleave a binary sequence a represented by the polynomial a ⁡ ( x ) = ∑ i = 0 n - 1 ⁢ a i ⁢ x i , where n=R.M with R≧M, i being an integer which may be written i=r.M+c, r and c being integers, r≧0 and c ε [0, M−1], there is obtained, from the sequence a, an interleaved binary sequence a*. The interleaved binary data sequence a* represented by the polynomial a * ⁡ ( x ) = ∑ i = 0 n - 1 ⁢ a i ⁢ x i * where i*=[r−h(c)].M+c mod n, the h(c) being obtained by the choice of an M-tuple h0=[h0(0), . . . , h0(M−1)] of non-negative integers less than R−1 such that, given a predetermined set Π of circulating matrices P of dimension M×M, for any matrix P of Π, the residues modulo R of the components of the vector h0.P are not nil; and the corresponding choice of an M-tuple h obtained from h0 by the application of a permutation moving h0(c) to position L×c mod M, the integer L being relatively prime with M. (It is noted that the above underlining of the variables, and the above single bracketing, is in the original and is meant to be permanent.)