A Carrier Synchronization Algorithm Based on Attached SYNC Marker for MPSK and MAPSK Modulation in Satellite Communications

Multiple Phase Shift Keying (MPSK) and Multiple Amplitude Phase Shift Keying (MAPSK) represent widely adopted modulation techniques in satellite communications, primarily due to their characteristic of low peak-to-average ratio. However, the rapid mobility of satellites induces substantial Doppler frequency shifts, which poses formidable challenges for carrier synchronization in coherent receivers. Consequently, this paper presents a carrier synchronization algorithm based on the Attached SYNC Marker (ASM). The proposed approach leverages the ASM embedded within the data frame structure as prior knowledge to estimate the carrier error and correct the local oscillator. Considering that the Doppler frequency offset may significantly exceed the estimated range, the Low Density Parity Check (LDPC) code syndrome check is employed to facilitate the determination of Doppler frequency. The experimental results confirm that the frequency estimation error is a few hundred hertz, the phase estimation error is around 0.1, and the maximum bit error rate (BER) performance loss is approximately 0.5dB. These results substantiate the effectiveness of proposed method in carrier synchronization for MPSK and MAPSK signals.