卫星相干光通信在国外已经接近工程应用阶段, 主流的传输接收方式为BPSK调制/零差探测, 接收端用光锁相环(OPLL)进行载波恢复。但即使在今天, 光锁相环的实现依然有难度, 而且存在捕获时间过长等现象。文中借鉴了现在的研究热点技术——光纤通信中的频偏估计、载波相位恢复技术, 针对星间激光通信中存在GHz量级大多普勒频移的工程背景, 提出了一种基于DSP的频偏开环补偿算法。从理论上分析了该算法的原理, 重点研究了激光器噪声和接收机噪声对频偏估计精度带来的影响, 并通过仿真进行了验证。本振光功率为10 dBm时, 当接收功率高于-47 dBm, 误码率优于10-4; 将接收功率提高10 dB后, 频偏估计标准差小于370 kHz。

Satellite coherent optical communication has reached the engineering application stage at abroad, and the mostly used modulation and demodulation technique are BPSK/homodyne detection, in which OPLL is used for carrier recovery. Even nowadays, the application of OPLL is still difficult and the OPLL takes long time to capture the received signal. The open-loop conpensation algorithm based on DSP used in fiber communication was proposed to estimate the frequency and phase, and then was applied to the satellite laser communications. The effect of laser noise and receiver noise on frequency estimation precision was studied emphaisitly, and simulation was implemented to verify the algorithm. Results show that when the power of local oscillator (LO) is 10 dBm, the BER of the system is better than 10-4 with received power higher than -47 dBm; when the received power is increased by 10 dB, the standard deviation of the frequency estimation is less than 370 kHz.