QUADRATURE FREQUENCY PHASE MODULATION

digital modulation method based on quadrature-carrier multiplexing of two N-dimensional biorthogonal signal sets is proposed. An embodiment of the proposed method referred to as Quadrature Frequency/Phase Modul ation (QFPM), and its continuous phase modification CP QFPM, are descr ibed. QFPM results when two NFSK/2PSK (combined frequency and phase sh ift keying) signals are quadrature-carrier multiplexed. The power effi ciency of QFPM and CP QFPM on the AWGN (additive white Gaussian noise) channel is always superior when compared to that of quadrature-amplit ude modulation (QAM), and their bandwidth efficiency is demonstrated t o be under certain conditions comparable or better than that of QAM. B oth schemes possess a self-synchronization capability. The demonstrate d performance characteristics of QPPM and CP QFPM suggest that they ma y be competitive with respect to QAM on channels where little or no fi ltering is desired.