CONVOLUTIONAL CODES.

This article introduces trellis diagrams, describes the fundamental add-compare-select computation, compares hard and soft decoding, and describes the suboptimal finite traceback version of Viterbi decoding. It states that convolutional codes represent one technique within the general class of channel codes. Channel codes--also called error-correction codes--permit reliable communication of an information sequence over a channel that adds noise, introduces bit errors, or otherwise distorts the transmitted signal.