Research On BPSK Carrier Acquisition Algorithm For Space Optical Communication

At present,space optical communication has become a research hotspot.When space optical communication is carried out,the Doppler shift can reach ±7 GHz due to the high frequency of laser and the relative speed between communication terminals,which makes it difficult to synchronize local carriers.Therefore,this essay is focusing on the BPSK carrier acquisition technology for space optical communication(1)For the problem of PLL losing lock when the Doppler frequency shift is large in the existing carrier acquisition system,a carrier acquisition system with double-loop control of precise tracking PLL and coarse tracking frequency estimation loop is proposed.The precise tracking PLL is used to stabilize the tracking phase-locked loop,and the coarse tracking loop is used to estimate and compensate the frequency difference signal when the PLL loses its lock.(2)The mathematical model of precise tracking phase-locked loop is established,and the relationship between optimal loop bandwidth and noise is obtained.An experimental platform is built to verify the acquisition performance of precise tracking phase-locked loop for BPSK signal carrier.The experimental results show that when the code rate is 5Gbps and the optical power of the signal is-40.5dBm,the precise tracking PLL can demodulate the baseband signal quickly,and the bit error rate is.(3)An overlapping band Nyquist folding receiver signal detection algorithm is proposed.Based on the traditional Nyquist folding receiver,the division structure of Nyquist domain is modified to solve the problem that the spectrum of signal frequency at the band boundary cannot be detected due to data truncation.The performance of the algorithm is verified by simulation.The simulation results show that when the signal frequency is 1.411 GHz and the SNR is greater than-16 dB,the correct decision probability of this algorithm can reach 100%,which is 7 dB higher than that of DF detection algorithm.When the signal frequency is 7.996 GHz and the SNR is higher than-14 dB,the mean MSE of signal estimation approaches the CRLB.