A systematic encoder adapted to receive an input information sequence S and output low-density parity-check convolutional codewords of a time varying period of g, wherein g is a natural number, the codewords presenting the information sequence S and parity sequence P, the encoder being operative to change a code rate of the encoder according to a selection of integer s in a coding rate formula ( s - 1)/ s, wherein s≤q, q is an integer equal to or greater than 3, the encoder thereby allowing a maximum coding rate of (q-1) / q and allowing a reduction of the coding rate from the maximum allowed coding rate to other values allowed by the coding rate formula; the encoder being adapted to use a low-density parity-check convolutional systematic code based on a parity check polynomial of equation B k D ⁢ P D + ∑ r = 1 s - 1 A Xr, k D ⁢ X r D + ∑ r = s q - 1 A Xr, k D ⁢ X r D = 0, wherein k = i mod g, k is an integer, i is an integer time index, X is a polynomial representation of a processed information sequence X obtained from the input information sequence S, D is a delay operator, P is a polynomial representation of the parity, A and B are, respectively, information and parity coefficient matrices, the encoder comprising: a coding rate setting section that is operative to change the coding rate to (s-1)/s according to the selection of the integer s; an information processing section that receives symbols S j,...,S j+s-2 of the input information sequence, wherein j is an integer, and sets symbols X r,i of the processed information sequence, wherein r=1, 2,..., s-1, to be S j,...,S j+s-2, respectively, and set symbols X r,i of the processed information sequence to be 0 for r taking values from s to (q-1); first to (q-1)-th computing sections (220-1, 220-2, 220-3) connected in parallel to receive the symbols X r,i of the processed information sequence, where r=1,... (q-1), from the information processing section such that each of these computing sections receives the respective symbol and computes a respective term A Xr,k X i of the parity check polynomial of said equation; a parity contribution computing section that receives as input a parity symbol P i-1 calculated at point in time with index i-1 and computes a term B k P of the parity check polynomial equation; an exclusive OR section that computes an exclusive OR of computation results of the first to (q-1)-th computing sections (220-1, 220-2, 220-3) and the computation result of the parity contribution computing section, as a parity symbol P i at point in time with index i, the encoding thereby being adapted to output, for the time with index i, the symbols X r,i of the processed information sequence, where r=1,..., (s-1), and the parity symbol P i. a coding rate setting section that is operative to change the coding rate to (s-1)/s according to the selection of the integer s; an information processing section that receives symbols S j,...,S j+s-2 of the input information sequence, wherein j is an integer, and sets symbols X r,i of the processed information sequence, wherein r=1, 2,..., s-1, to be S j,...,S j+s-2, respectively, and set symbols X r,i of the processed information sequence to be 0 for r taking values from s to (q-1); first to (q-1)-th computing sections (220-1, 220-2, 220-3) connected in parallel to receive the symbols X r,i of the processed information sequence, where r=1,... (q-1), from the information processing section such that each of these computing sections receives the respective symbol and computes a respective term A Xr,k X i of the parity check polynomial of said equation; a parity contribution computing section that receives as input a parity symbol P i-1 calculated at point in time with index i-1 and computes a term B k P of the parity check polynomial equation; an exclusive OR section that computes an exclusive OR of computation results of the first to (q-1)-th computing sections (220-1, 220-2, 220-3) and the computation result of the parity contribution computing section, as a parity symbol P i at point in time with index i, the encoding thereby being adapted to output, for the time with index i, the symbols X r,i of the processed information sequence, where r=1,..., (s-1), and the parity symbol P i.