Abstract: An ATV receiver is provided with a 16-state trellis decoder to achieve improved performance in the presence of NTSC co-channel interference. In one embodiment, the ATV receiver comprises a tuner, a comb filter, and a trellis decoder. The tuner is configured to downmix a selected channel frequency signal to an intermediate frequency signal, where the comb filter is configurable to screen out most of the NTSC co-channel interference. The intermediate frequency receive signal is modified by the comb filter to resemble a partial response signal. The trellis decoder the demodulates the partial response signal in an improved fashion taking into account the state of the trellis encoder and the partial response channel. The trellis decoder may have a 16 state trellis comprised of four 4-state butterflies wherein each edge in the trellis is a single transition.