A CONVOLUTION DECODER USING THE VITERBI ALGORITHM

A convolution decoder includes, for each state S of a shift register receiving an initial signal, an add-compare-select circuit which provides a one-bit decision for selecting either one of states 2S or 2S+1 as a state preceding the current state S. A decoding element traces back the memory according to a path indicated by the decisions stored in the memory in order to restore the succession of states of the initial signal. Each calculation cell associated with a state S further includes means for establishing a complex R-bit decision comprising, by decreasing weight, the one-bit decision of the calculation cell and the R-1 most significant bits of the complex decision established by the cell associated with the selected state 2S or 2S+1.