DECODING CIRCUIT FOR CONVOLUTIONAL CODES FOR THE EXECUTION OF THE REVERSE STORAGE AND EXPLORATION STAGE OF SURFACE ROADS OF A VITERBI ALGORITHM.

摘要

This decoding consists of exploring in the opposite direction a plurality of paths of a trellis representative of a diagram of possible transitions resulting from coding by a v-flip-coder, each node of the trellis being represented by a word of N = 2v bits. . BR/ The circuit operates in such a way as to select, from a plurality of possible surviving paths, that presenting the weakest metric, so as to reconstruct the trellis path actually described during coding and to find the sequence of bits of information having caused the path of this path. BR/ According to the invention, the circuit comprises a memory (20) storing a plurality of said words (D ') of N = 2v bits and, at the output of this memory, cascading of v groups of multiplexers 2- in-1 (21, 22, 23, 24, 25, 26), progressively reducing the 2v outputs of the memory to a single output, a D flip-flop (31, 32, 33, 34, 35, 36) being output of each multiplexer. BR/ The last, unique, the most downstream flip-flop (36) sequentially outputs the information bits (S (t-6)) corresponding to the searched path, and the selection signal of each multiplexer is directly given by the exit of this last rocker.