Modulation recognition of composite modulation signal based on two-fold digital receiver and goodness of fit test

Aiming at the modulation recognition problem of mixed signal set {BPSK, QPSK, BPSK-FM, QPSK-FM} with unknown parameters, this paper proposes a modulation recognition algorithm based on two-fold PLL (phase locked loop) and goodness of fit test. The PLL is used to extract the features of the composite modulation signal, and the goodness of fit test is used to measure the distance of the phase cumulative distribution of the demodulation information. Theoretical analysis and simulation results show that the performance of the recognition method based on two-fold PLL and goodness of fit test is better than the widely used modulation recognition method based on constellation.