Patent ID: 6256352
Filing Date: 2001-07-03
Classification: H03M,H04L,H04N

Abstract:
A trellis coded modulation (TCM) decoder in a digital television receiver using a comb filter for removing the effect of an NTSC signal, comprising:a branch metric generator calculating a Euclidian distance between a received input data and a reference signal, corresponding to the case of 8-state passing through the comb filter and the case of 4-state not passing through the comb filter, and generating a branch metric value of a path having the smallest value from parallel-transited paths, according to each state and a parallel-transition path select signal wherein said each state is based on a trellis state diagram having transition to share 4-state and 8-state;an addition-comparison selector adding a branch metric value with respect to the parallel-transited path obtained by the branch metric generator to a previous accumulated path metric value, and comparing the added results according to each state to generate the smallest path metric value and a corresponding path select signal; anda trace-back memory tracing-back the trellis using the path select signal and the path metric values of each state, corresponding to both the 4-state and the 8-state, to thereby decode an original signal, in units of a predetermined number of symbols corresponding to interleaving in units of the predetermined number of symbols.