CORRELATIVE PHASE SHIFT KEYING. A BANDWIDTH AND POWER EFFICIENT CONSTANT ENVELOPE MODULATION.

Correlative Phase Shift Keying (CORPSK) is introduced. It is a constant envelope modulation technique with smooth transitions between fixed phase positions, while successive transitions are correlated. A number of CORPSK numbers for 2 and 4 input levels is described, including Tamed Frequency Modulation (TFM). The necessary bandwidth appears to be at least equivalent to other constant envelope modulation techniques as MSK, QPSK and CPFSK; the out-of-band radiation is much lower. Carrier extraction can be realized with simple techniques, so that coherent detection with optimum receiver performance is practically feasible. Simulation results are presented for coherent as well as noncoherent detection. An error performance of 2 db better than for DQPSK can be obtained for CORPSK with four phase positions. Practical results for TFM are reported.