Abstract :
P.Szulakiewicz and R.Kotrys (see ibid., vol.30, no.13, pp.1032-1033) presented new 4PSK-2PSK multi-D trellis codes which allow a demodulator to lock onto the 2PSK signal set, achieving greater robustness to phase slips in a noisy environment. For the criteria used, i.e. maximum free squared Euclidean distance and minimum number of nearest neighbours, the authors suggest that their codes are not the best
