pam 4d4D-PAM5 is the method used to transmit data at 1 Gbsec over four wire pairs using five snaling levels. It combines 8B1Q4, Trellis, Viterbi, and 4D coding and decoding, and is4D-PAM5 is the method used to transmit data at 1 Gbsec over four wire pairs using five snaling levels. It combines 8B1Q4, Trellis, Viterbi, and 4D coding and decoding, and is