Abstract:

More than 90% of the signal in the satellite channel use phase or amplitude and phase united modulation scheme including MPSK, MQAM, MAPSK, etc. In shortwave communications and mobile communications, MPSK is also one of the most common signal types in addition. Carrier synchronization is crucial and the central part in signal demodulation. A thorough research on the constellation distribution of amplitudephase modulated (APM) signal is conducted under the condition of noncooperation receiving, and then a synchronization algorithm is proposed based on constellation density statistics which realizes the blind elimination of carrier offset and constellation recovery. This algorithm does not require a modulation recognition in advance, less amount of data, low complexity, good antinoise performance, and it can be widely used in conventional signals and unknown, burst signal demodulation. The simulation results show that the performance of the algorithm gets close to CramerRao bound under the condition that the signal to noise ratio gets close to the bound of demodulation, and verify the reliability to engineering practice.