1. Decoding method including the following steps: a. define a source model designed to define probabilities for x-ary symbols (S k )associated with transitions between source states (C k ) in a source state diagram, a. so-called “product” model, designed to define a correspondence between the x-ary symbols and first binary elements, in relation to product states in a “product” state diagram, a product state being a function of a source state, b. receive “channel” properties designed to define probabilities of receiving second binary elements, upon transmission of first binary elements, c. for a received coded flow of second binary elements, calculate the probabilities of decoding x-ary symbols, knowing bits of the flow of second binary elements, or the probabilities of arriving at product states knowing bits of the flow of second binary elements, from the channel properties of the source model and of the product model, d. reconstitute the most probable flow of x-ary symbols from the probabilities computed at step c.