DIGITAL SIGNAL DECODING SYSTEM

摘要

PROBLEM TO BE SOLVED: To provide a digital signal decoder which realizes minimizing a decoding impossible area occurring when time-varying structure cannot be controlled in the case of performing Viterbi decoding by using a trellis having the time-varying structure. SOLUTION: In the case of decoding a decoding system from a decoder input signal by using a time-varying trellis where the number of states and transition vary depending on the time, time deviation on the time-varying trellis is judged by a decoding system judgment circuit by using a TCPR Viterbi decorded system decoded by using the time-varying trellis and a PR Viterbi decoded system decoded by using a non-time-varying trellis to obtain a decoding system selection signal. With the decoding system selection signal, a selector selects the PR Viterbi decoded system when there is time deviation on the time-varying trellis, and selects the TCPR Viterbi decoded system when there is not time deviation. COPYRIGHT: (C)2004,JPO&NCIPI