Patent ID: 7426681

Claim:
A Viterbi detector for maximum-likelihood decoding of a convolutionally-encoded input signal, comprising: a branch metric calculating section for calculating branch metrics from the convolutionally-encoded input signal; an ACS (Add-Compare-Select) operation section for calculating a path metric for each state at a present time using both a path metric of a previous time in a surviving path of that state and a corresponding branch metric calculated by the branch metric calculating section, and outputting a path select signal corresponding to a metric selected by the ACS operation; a path-select-signal memory section responsive to the path select signal, for outputting, at a present time, decoded data in a surviving path having a prescribed constraint length, wherein the data are decoded at a corresponding branch a prescribed time ago; and a maximum-likelihood determination section for determining most likely decoded data from each decoded data received from the path-select-signal memory section, wherein the path-select-signal memory section includes a shift register for storing the path select signals in order of time, a selector train formed by a plurality of selectors for receiving values stored in respective cells of the shift register as a select signal, and a binary output unit for outputting a decoded bit corresponding to a branch that is decoded a prescribed time ago in the surviving path.