Abstract: A quadrature amplitude modulation (QAM) trellis coded modulation (TCM) decoder for decoding a stream of QAM TCM signals is disclosed. Each of the signals has a plurality of associated branch metrics and has an in-phase component and a quadrature component. The in-phase component is defined by a plurality of in-phase symbols and the quadrature component is defined by a plurality of quadrature symbols. The QAM TCM decoder includes a first Viterbi decoder and a second Viterbi decoder. The first Viterbi decoder is configured to receive an in-phase component of a QAM TCM signal for decoding the associated in-phase symbols into an in-phase decoded bit and a plurality of uncoded in-phase bits. The second Viterbi decoder configured to receive a quadrature component of the QAM TCM signal for decoding the associated quadrature symbols into a quadrature decoded bit and a plurality of uncoded quadrature bits. The first and second Viterbi decoders are adapted to decode 64- or 256-QAM TCM signals.

Abstract: An apparatus for recovering information bits from in-phase and quadrature components of a stream of quadrature amplitude modulation (QAM) trellis code modulation (TCM) signals is disclosed. Each signal has an in-phase component and a quadrature component. The in-phase component includes a decoded bit and a plurality of uncoded in-phase bits and the quadrature component includes a decoded quadrature bit and a plurality of uncoded quadrature bits. The apparatus includes a reencode and puncturing circuitry, an inverse mapping circuitry, and a recovery circuitry. The reencode and puncture circuitry is adapted to receive the in-phase and quadrature components of a QAM TCM signal for encoding the decoded in-phase and quadrature bits. The reencode and puncture circuitry punctures the encoded in-phase bit with the uncoded in-phase bits to generate an in-phase component index.