Patent ID: 6201563
Filing Date: 2001-03-13
Classification: H03M,H04N

Abstract:
An ATV receiver with improved performance when subjected to NTSC co-channel interference, wherein the receiver comprises:a tuner configured to downmix a selected channel frequency signal to an intermediate frequency signal;a comb filter coupled to receive the intermediate frequency signal and configured to attenuate NTSC carrier frequencies from the intermediate frequency signal to produce a partial response signal;a trellis decoder coupled to receive the partial response signal and configured to demodulate the partial response signal to produce decoded symbols using a 16 state trellis, wherein each stage of the 16 state trellis comprises four transitions leaving each state corresponding to four bipartite graphs such that each bipartite graph includes four source states and four destination states, and wherein an encoder state (S.sub.0 S.sub.1) and partial response channel state (D) form the four bipartite graphs having the following sets of source states and destination states:bipartite graph source states destination states first (0,0,-7), (0,0,-3), (0,0,-7), (0,0,+1), (0,0,+1), (0,0,+5) (0,1,-3), (0,1,+5) second (0,1,-7), (0,1,-3), (1,0,-5), (1,0,+3), (0,1,+1), (0,1,+5) (1,1,-1), (1,1,+7) third (1,0,-5), (1,0,-1), (0,0,-3), (0,0,+5), (1,0,+3), (1,0,+7) (0,1,-7), (0,1,+1) fourth (1,1,-5), (1,1,-1), (1,0,-1), (1,0,+7), (1,1,+3), (1,1,+7) (1,1,-5), (1,1,+3)