针对星间激光通信系统受平台抖动影响的问题,研究了在瞄准误差影响下,具有有限消光比的多进制脉冲位置调制(M-ary PPM)系统的误码性能。通过分析发射机消光比、平台抖动和接收机噪声的影响,得到系统误比特率与信噪比关系式,并进行仿真分析。仿真结果表明:系统误比特率与归一化抖动标准差、PPM的调制阶数、发射机消光比三个因素有关,且瞄准误差和发射机消光比对通信系统性能造成的影响互不相关。通过分析系统总功率损失,可知系统的误比特率并不随着调制阶数的增大而一直降低。因此,研究表明在商用发射机消光比为20 dB的情况下,采用16-PPM的调制方式是最优的选择。

Platform jitter is an important source of bit error in an intersatellite laser communication system. In this study, we investigate the error performance of the M-ary pulse position modulation (M-ary PPM) system with a finite extinction ratio under the influence of sighting error. Further, we obtain the relation between the bit error rate of the system and the signal-to-noise ratio based on the effects of the transmitter’s extinction ratio, platform jitter, and receiver noise. The simulation results show that the bit error rate is related to the normalized standard deviation with respect to platform jitter, the number of PPM orders, and the extinction ratio of the transmitter. Furthermore, the effects of pointing error on the performance of the communication system are independent of the extinction ratio of the transmitter. The system bit error rate does not necessarily decrease with the increasing number of modulation orders based on the analysis of the total power loss of the system. 16-PPM is the optimal choice in case of a commercial transmitter with an extinction ratio of 20 dB.