Performance of 12PM3 modulation methods in digital land mobile radio with discrimination detection

The performance of a number of narrowband continuous-phase modulation methods, belonging to the 12PM3 class (12-state, Phase Modulation with correlation over 3 consecutive bits), has been compared with reference to both AWGN (Additive White Gaussian Noise) channels and the typical propagation conditions envisaged for SCPC/FDMA digital land mobile radio systems in urban environment. Demodulation has been performed by frequency discrimination using at the receiving end pre- and post-discrimination filters optimized for the best performance. Different decision techniques have been considered, namely 2-TH (2-Threshold), 4-TH, mixed 2-TH/4-TH and MLSE (Maximum Likelyhood Sequence Estimation) techniques.